Springboard

Student - Data Science Career Track

Data cleaning, data wrangling, Git, Jupyter notebooks, Python (Matplotlib, NumPy, pandas, seaborn, statsmodels, pymc3), frequentist statistics, Bayesian statistics, bootstrap statistics, A/B testing, MySQL

Foothill College

Professor of Biology, Part-time

I design curricula and lead a variety of major’s and non-major’s undergraduate courses in the Biological and Health Sciences.

Webb Ecological

Freelance Wildlife Biologist

I design, implement and communicate results of ecological studies. As an independent contractor, I have served a number of private consultants, non-profit groups and public agencies. I have also authored several scientific publications and technical reports. My experience includes working with several sensitive species including marbled murrelet, desert tortoise, California red-legged frog, California tiger salamander, and burrowing owls. A list of some of the projects I have worked on can be found at the link below and/or at the following web address: http://www.williamwebbsite.com/wp/wildlife-ecology-projects/

Cañada Community College

Environmental Sciences Instructor

I designed and led a non-major's undergraduate course in Environmental Science.

Idaho State University and U.S. Geological Survey

Postdoctoral Researcher:, Part-time

I conducted literature reviews and authored scientific manuscripts related to conservation biology.

Linking resource use with demographic parameters in a synanthropic population of Common Ravens.

Biological Conservation 144:2264-2273.

A thorough understanding of a population’s ecology requires knowledge of the relationship between habitat use, resource use and demographic parameters. We undertook an empirical investigation of habitat use, resource use and demography in a population of common ravens (Corvus corax), a species widely distributed throughout the Northern Hemisphere. The abundance of ravens is increasing in many parts of western North America, which represents a conservation concern since predation by ravens is thought to contribute to the decline of several sensitive species. We defined resources as the suite of physical and biological components in the environment that led to occupancy of a particular place by ravens. The home ranges of breeding and nonbreeding ravens contained similar proportions of resources, but breeding ravens used more edges, roads, forest, clearcuts, and towns than nonbreeders. We detected no differences in survival between the sexes, but breeding ravens survived at higher rates than nonbreeders, due to exclusion by breeding ravens from those resources positively associated with survival. Raven use of mature forests and anthropogenic land use types was positively associated with survival. Breeding raven use of clearcuts and patchy areas contributed to increased reproduction, but the use of clearcuts along with the use of roads was negatively associated with survival due to illegal shooting. Greater insight into the demography of synanthropic species such as the common raven will enable managers to make informed decisions for protecting biodiversity. This study is the first to consider the demographic consequences of habitat use and resource use for both nonbreeding and breeding common ravens.

Linking resource use with demographic parameters in a synanthropic population of Common Ravens.

Biological Conservation 144:2264-2273.

A thorough understanding of a population’s ecology requires knowledge of the relationship between habitat use, resource use and demographic parameters. We undertook an empirical investigation of habitat use, resource use and demography in a population of common ravens (Corvus corax), a species widely distributed throughout the Northern Hemisphere. The abundance of ravens is increasing in many parts of western North America, which represents a conservation concern since predation by ravens is thought to contribute to the decline of several sensitive species. We defined resources as the suite of physical and biological components in the environment that led to occupancy of a particular place by ravens. The home ranges of breeding and nonbreeding ravens contained similar proportions of resources, but breeding ravens used more edges, roads, forest, clearcuts, and towns than nonbreeders. We detected no differences in survival between the sexes, but breeding ravens survived at higher rates than nonbreeders, due to exclusion by breeding ravens from those resources positively associated with survival. Raven use of mature forests and anthropogenic land use types was positively associated with survival. Breeding raven use of clearcuts and patchy areas contributed to increased reproduction, but the use of clearcuts along with the use of roads was negatively associated with survival due to illegal shooting. Greater insight into the demography of synanthropic species such as the common raven will enable managers to make informed decisions for protecting biodiversity. This study is the first to consider the demographic consequences of habitat use and resource use for both nonbreeding and breeding common ravens.

Comparative analysis of knowledge representation and reasoning requirements across a range of life sciences textbooks

Journal of Biomedical Semantics 5: 51.

Using knowledge representation for biomedical projects is now commonplace. In previous work, we represented the knowledge found in a college-level biology textbook in a fashion useful for answering questions. We showed that embedding the knowledge representation and question-answering abilities in an electronic textbook helped to engage student interest and improve learning. A natural question that arises from this success, and this paper’s primary focus, is whether a similar approach is applicable across a range of life science textbooks. To answer that question, we considered four different textbooks, ranging from a below-introductory college biology text to an advanced, graduate-level neuroscience textbook. For these textbooks, we investigated the following questions: (1) To what extent is knowledge shared between the different textbooks? (2) To what extent can the same upper ontology be used to represent the knowledge found in different textbooks? (3) To what extent can the questions of interest for a range of textbooks be answered by using the same reasoning mechanisms?

Linking resource use with demographic parameters in a synanthropic population of Common Ravens.

Biological Conservation 144:2264-2273.

A thorough understanding of a population’s ecology requires knowledge of the relationship between habitat use, resource use and demographic parameters. We undertook an empirical investigation of habitat use, resource use and demography in a population of common ravens (Corvus corax), a species widely distributed throughout the Northern Hemisphere. The abundance of ravens is increasing in many parts of western North America, which represents a conservation concern since predation by ravens is thought to contribute to the decline of several sensitive species. We defined resources as the suite of physical and biological components in the environment that led to occupancy of a particular place by ravens. The home ranges of breeding and nonbreeding ravens contained similar proportions of resources, but breeding ravens used more edges, roads, forest, clearcuts, and towns than nonbreeders. We detected no differences in survival between the sexes, but breeding ravens survived at higher rates than nonbreeders, due to exclusion by breeding ravens from those resources positively associated with survival. Raven use of mature forests and anthropogenic land use types was positively associated with survival. Breeding raven use of clearcuts and patchy areas contributed to increased reproduction, but the use of clearcuts along with the use of roads was negatively associated with survival due to illegal shooting. Greater insight into the demography of synanthropic species such as the common raven will enable managers to make informed decisions for protecting biodiversity. This study is the first to consider the demographic consequences of habitat use and resource use for both nonbreeding and breeding common ravens.

Comparative analysis of knowledge representation and reasoning requirements across a range of life sciences textbooks

Journal of Biomedical Semantics 5: 51.

Using knowledge representation for biomedical projects is now commonplace. In previous work, we represented the knowledge found in a college-level biology textbook in a fashion useful for answering questions. We showed that embedding the knowledge representation and question-answering abilities in an electronic textbook helped to engage student interest and improve learning. A natural question that arises from this success, and this paper’s primary focus, is whether a similar approach is applicable across a range of life science textbooks. To answer that question, we considered four different textbooks, ranging from a below-introductory college biology text to an advanced, graduate-level neuroscience textbook. For these textbooks, we investigated the following questions: (1) To what extent is knowledge shared between the different textbooks? (2) To what extent can the same upper ontology be used to represent the knowledge found in different textbooks? (3) To what extent can the questions of interest for a range of textbooks be answered by using the same reasoning mechanisms?

Common Raven juvenile survival in a human-augmented landscape.

Condor 106:517-528.

Anthropogenic resource subsidies have contributed to the dramatic increase in the abundance of Common Ravens (Corvus corax) in the western Mojave Desert, California, during the past 30 years. To better understand the effects of these subsidies on raven demography, we examined whether survival to juvenile departure from the natal territory could be predicted by a set of environmental and morphological variables, such as nest proximity to anthropogenic resources and juvenile condition. We captured 240 juvenile ravens over 2 years and marked them prior to fledging. Nest proximity to anthropogenic resources and earlier fledging dates significantly predicted raven juvenile survival to departure from the natal territory. The best-fitting mark-recapture models predicted postdeparture survival as a function of time since fledging, nest proximity to anthropogenic resources, and year hatched. The positive effect of nest proximity to anthropogenic resources influenced postdeparture survival for at least 9 months after fledging, as revealed by the mark-recapture analysis. Annual survival was 47% for first-year, 81% for second-year, and 83% for third-year birds. Our results support the hypothesis that anthropogenic resources contribute to increasing raven numbers via increased juvenile survival to departure as well as increased postdeparture survival. We expect raven numbers to grow in concert with the growing human presence in the Mojave Desert unless raven access to anthropogenic resources is diminished

Linking resource use with demographic parameters in a synanthropic population of Common Ravens.

Biological Conservation 144:2264-2273.

A thorough understanding of a population’s ecology requires knowledge of the relationship between habitat use, resource use and demographic parameters. We undertook an empirical investigation of habitat use, resource use and demography in a population of common ravens (Corvus corax), a species widely distributed throughout the Northern Hemisphere. The abundance of ravens is increasing in many parts of western North America, which represents a conservation concern since predation by ravens is thought to contribute to the decline of several sensitive species. We defined resources as the suite of physical and biological components in the environment that led to occupancy of a particular place by ravens. The home ranges of breeding and nonbreeding ravens contained similar proportions of resources, but breeding ravens used more edges, roads, forest, clearcuts, and towns than nonbreeders. We detected no differences in survival between the sexes, but breeding ravens survived at higher rates than nonbreeders, due to exclusion by breeding ravens from those resources positively associated with survival. Raven use of mature forests and anthropogenic land use types was positively associated with survival. Breeding raven use of clearcuts and patchy areas contributed to increased reproduction, but the use of clearcuts along with the use of roads was negatively associated with survival due to illegal shooting. Greater insight into the demography of synanthropic species such as the common raven will enable managers to make informed decisions for protecting biodiversity. This study is the first to consider the demographic consequences of habitat use and resource use for both nonbreeding and breeding common ravens.

Comparative analysis of knowledge representation and reasoning requirements across a range of life sciences textbooks

Journal of Biomedical Semantics 5: 51.

Using knowledge representation for biomedical projects is now commonplace. In previous work, we represented the knowledge found in a college-level biology textbook in a fashion useful for answering questions. We showed that embedding the knowledge representation and question-answering abilities in an electronic textbook helped to engage student interest and improve learning. A natural question that arises from this success, and this paper’s primary focus, is whether a similar approach is applicable across a range of life science textbooks. To answer that question, we considered four different textbooks, ranging from a below-introductory college biology text to an advanced, graduate-level neuroscience textbook. For these textbooks, we investigated the following questions: (1) To what extent is knowledge shared between the different textbooks? (2) To what extent can the same upper ontology be used to represent the knowledge found in different textbooks? (3) To what extent can the questions of interest for a range of textbooks be answered by using the same reasoning mechanisms?

Common Raven juvenile survival in a human-augmented landscape.

Condor 106:517-528.

Anthropogenic resource subsidies have contributed to the dramatic increase in the abundance of Common Ravens (Corvus corax) in the western Mojave Desert, California, during the past 30 years. To better understand the effects of these subsidies on raven demography, we examined whether survival to juvenile departure from the natal territory could be predicted by a set of environmental and morphological variables, such as nest proximity to anthropogenic resources and juvenile condition. We captured 240 juvenile ravens over 2 years and marked them prior to fledging. Nest proximity to anthropogenic resources and earlier fledging dates significantly predicted raven juvenile survival to departure from the natal territory. The best-fitting mark-recapture models predicted postdeparture survival as a function of time since fledging, nest proximity to anthropogenic resources, and year hatched. The positive effect of nest proximity to anthropogenic resources influenced postdeparture survival for at least 9 months after fledging, as revealed by the mark-recapture analysis. Annual survival was 47% for first-year, 81% for second-year, and 83% for third-year birds. Our results support the hypothesis that anthropogenic resources contribute to increasing raven numbers via increased juvenile survival to departure as well as increased postdeparture survival. We expect raven numbers to grow in concert with the growing human presence in the Mojave Desert unless raven access to anthropogenic resources is diminished

Interbreeding Between Cryptic Lineages of the Common Raven: Evidence for Speciation in Reverse.

Molecular Ecology 20(11):2390-2402.

DNA sequence studies frequently reveal evidence of cryptic lineages in morphologically uniform species, many of which turn out to be evolutionarily distinct species. The Common Raven (Corvus corax) includes two deeply divergent mtDNA lineages: one lineage seems restricted to western North America and the other is Holarctic in distribution. These deep clades hint of the possibility of cryptic species in the western United States. We tested this hypothesis in a population consisting of an equal proportion of both mtDNA clades, by quantifying mating patterns and associated fitness consequences with respect to mtDNA. We also tested for morphological, behavioural and ecological correlates of sex and mtDNA clade membership. Mate pairings were random with respect to mtDNA clades, and there were no differences in reproductive success between assortatively and nonassortatively mated pairs. We found no differences in survival or resource use between clades. There were no differences in morphological or behavioural characters between mtDNA clades, except one clade trended towards greater mobility. These results suggest there are no barriers to gene flow between mtDNA clades and argue that the mtDNA clades have remerged in this population, likely due to a lack of ecological or signal differentiation between individuals in each lineage. Hence, in Common Ravens, phylogeographic structure in mtDNA is a reflection of likely past isolation rather than currently differentiated species.

Linking resource use with demographic parameters in a synanthropic population of Common Ravens.

Biological Conservation 144:2264-2273.

A thorough understanding of a population’s ecology requires knowledge of the relationship between habitat use, resource use and demographic parameters. We undertook an empirical investigation of habitat use, resource use and demography in a population of common ravens (Corvus corax), a species widely distributed throughout the Northern Hemisphere. The abundance of ravens is increasing in many parts of western North America, which represents a conservation concern since predation by ravens is thought to contribute to the decline of several sensitive species. We defined resources as the suite of physical and biological components in the environment that led to occupancy of a particular place by ravens. The home ranges of breeding and nonbreeding ravens contained similar proportions of resources, but breeding ravens used more edges, roads, forest, clearcuts, and towns than nonbreeders. We detected no differences in survival between the sexes, but breeding ravens survived at higher rates than nonbreeders, due to exclusion by breeding ravens from those resources positively associated with survival. Raven use of mature forests and anthropogenic land use types was positively associated with survival. Breeding raven use of clearcuts and patchy areas contributed to increased reproduction, but the use of clearcuts along with the use of roads was negatively associated with survival due to illegal shooting. Greater insight into the demography of synanthropic species such as the common raven will enable managers to make informed decisions for protecting biodiversity. This study is the first to consider the demographic consequences of habitat use and resource use for both nonbreeding and breeding common ravens.

Comparative analysis of knowledge representation and reasoning requirements across a range of life sciences textbooks

Journal of Biomedical Semantics 5: 51.

Using knowledge representation for biomedical projects is now commonplace. In previous work, we represented the knowledge found in a college-level biology textbook in a fashion useful for answering questions. We showed that embedding the knowledge representation and question-answering abilities in an electronic textbook helped to engage student interest and improve learning. A natural question that arises from this success, and this paper’s primary focus, is whether a similar approach is applicable across a range of life science textbooks. To answer that question, we considered four different textbooks, ranging from a below-introductory college biology text to an advanced, graduate-level neuroscience textbook. For these textbooks, we investigated the following questions: (1) To what extent is knowledge shared between the different textbooks? (2) To what extent can the same upper ontology be used to represent the knowledge found in different textbooks? (3) To what extent can the questions of interest for a range of textbooks be answered by using the same reasoning mechanisms?

Common Raven juvenile survival in a human-augmented landscape.

Condor 106:517-528.

Anthropogenic resource subsidies have contributed to the dramatic increase in the abundance of Common Ravens (Corvus corax) in the western Mojave Desert, California, during the past 30 years. To better understand the effects of these subsidies on raven demography, we examined whether survival to juvenile departure from the natal territory could be predicted by a set of environmental and morphological variables, such as nest proximity to anthropogenic resources and juvenile condition. We captured 240 juvenile ravens over 2 years and marked them prior to fledging. Nest proximity to anthropogenic resources and earlier fledging dates significantly predicted raven juvenile survival to departure from the natal territory. The best-fitting mark-recapture models predicted postdeparture survival as a function of time since fledging, nest proximity to anthropogenic resources, and year hatched. The positive effect of nest proximity to anthropogenic resources influenced postdeparture survival for at least 9 months after fledging, as revealed by the mark-recapture analysis. Annual survival was 47% for first-year, 81% for second-year, and 83% for third-year birds. Our results support the hypothesis that anthropogenic resources contribute to increasing raven numbers via increased juvenile survival to departure as well as increased postdeparture survival. We expect raven numbers to grow in concert with the growing human presence in the Mojave Desert unless raven access to anthropogenic resources is diminished

Interbreeding Between Cryptic Lineages of the Common Raven: Evidence for Speciation in Reverse.

Molecular Ecology 20(11):2390-2402.

DNA sequence studies frequently reveal evidence of cryptic lineages in morphologically uniform species, many of which turn out to be evolutionarily distinct species. The Common Raven (Corvus corax) includes two deeply divergent mtDNA lineages: one lineage seems restricted to western North America and the other is Holarctic in distribution. These deep clades hint of the possibility of cryptic species in the western United States. We tested this hypothesis in a population consisting of an equal proportion of both mtDNA clades, by quantifying mating patterns and associated fitness consequences with respect to mtDNA. We also tested for morphological, behavioural and ecological correlates of sex and mtDNA clade membership. Mate pairings were random with respect to mtDNA clades, and there were no differences in reproductive success between assortatively and nonassortatively mated pairs. We found no differences in survival or resource use between clades. There were no differences in morphological or behavioural characters between mtDNA clades, except one clade trended towards greater mobility. These results suggest there are no barriers to gene flow between mtDNA clades and argue that the mtDNA clades have remerged in this population, likely due to a lack of ecological or signal differentiation between individuals in each lineage. Hence, in Common Ravens, phylogeographic structure in mtDNA is a reflection of likely past isolation rather than currently differentiated species.

Differences in space use by Common Ravens in relation to sex, breeding status and kinship

The Condor 114(3):1-11.

Group differences in avian space use relate to group differences in resource use and demographic parameters. However, studies that consider year-round, intraspecific variation in the space use of noncooperatively breeding species are relatively rare. A greater understanding of factors relating to intraspecific variation in space use is especially important for managing human-subsidized predators, such as the Common Raven (Corvus corax). We hypothesized that sex, sociality, and the distribution of bonanzas of food should influence year-round space use by breeding and nonbreeding Common Ravens on the Olympic Peninsula of Washington State. We detected differences in space use between breeders and nonbreeders but not between the sexes. Breeders shared little space with their neighbors and displayed strong site fidelity, except in the fall and winter or after the death of a mate, when some breeding ravens moved extensively. Nonbreeders moved widely, were more gregarious, and their home ranges intersected a greater proportion of communal food resources than did those of breeders. Breeders shared little space with their adult neighbors, but they shared more space with nonbreeders when communal food resources fell within their territories. Pair bonds were broken only by the death of a partner, which in some cases was followed by extensive movements by the surviving adult prior to pairing with a new mate or settling in a new breeding territory. This study is the first to consider the space use of both nonbreeding and breeding Common Ravens in the same population simultaneously

Linking resource use with demographic parameters in a synanthropic population of Common Ravens.

Biological Conservation 144:2264-2273.

A thorough understanding of a population’s ecology requires knowledge of the relationship between habitat use, resource use and demographic parameters. We undertook an empirical investigation of habitat use, resource use and demography in a population of common ravens (Corvus corax), a species widely distributed throughout the Northern Hemisphere. The abundance of ravens is increasing in many parts of western North America, which represents a conservation concern since predation by ravens is thought to contribute to the decline of several sensitive species. We defined resources as the suite of physical and biological components in the environment that led to occupancy of a particular place by ravens. The home ranges of breeding and nonbreeding ravens contained similar proportions of resources, but breeding ravens used more edges, roads, forest, clearcuts, and towns than nonbreeders. We detected no differences in survival between the sexes, but breeding ravens survived at higher rates than nonbreeders, due to exclusion by breeding ravens from those resources positively associated with survival. Raven use of mature forests and anthropogenic land use types was positively associated with survival. Breeding raven use of clearcuts and patchy areas contributed to increased reproduction, but the use of clearcuts along with the use of roads was negatively associated with survival due to illegal shooting. Greater insight into the demography of synanthropic species such as the common raven will enable managers to make informed decisions for protecting biodiversity. This study is the first to consider the demographic consequences of habitat use and resource use for both nonbreeding and breeding common ravens.

Comparative analysis of knowledge representation and reasoning requirements across a range of life sciences textbooks

Journal of Biomedical Semantics 5: 51.

Using knowledge representation for biomedical projects is now commonplace. In previous work, we represented the knowledge found in a college-level biology textbook in a fashion useful for answering questions. We showed that embedding the knowledge representation and question-answering abilities in an electronic textbook helped to engage student interest and improve learning. A natural question that arises from this success, and this paper’s primary focus, is whether a similar approach is applicable across a range of life science textbooks. To answer that question, we considered four different textbooks, ranging from a below-introductory college biology text to an advanced, graduate-level neuroscience textbook. For these textbooks, we investigated the following questions: (1) To what extent is knowledge shared between the different textbooks? (2) To what extent can the same upper ontology be used to represent the knowledge found in different textbooks? (3) To what extent can the questions of interest for a range of textbooks be answered by using the same reasoning mechanisms?

Common Raven juvenile survival in a human-augmented landscape.

Condor 106:517-528.

Anthropogenic resource subsidies have contributed to the dramatic increase in the abundance of Common Ravens (Corvus corax) in the western Mojave Desert, California, during the past 30 years. To better understand the effects of these subsidies on raven demography, we examined whether survival to juvenile departure from the natal territory could be predicted by a set of environmental and morphological variables, such as nest proximity to anthropogenic resources and juvenile condition. We captured 240 juvenile ravens over 2 years and marked them prior to fledging. Nest proximity to anthropogenic resources and earlier fledging dates significantly predicted raven juvenile survival to departure from the natal territory. The best-fitting mark-recapture models predicted postdeparture survival as a function of time since fledging, nest proximity to anthropogenic resources, and year hatched. The positive effect of nest proximity to anthropogenic resources influenced postdeparture survival for at least 9 months after fledging, as revealed by the mark-recapture analysis. Annual survival was 47% for first-year, 81% for second-year, and 83% for third-year birds. Our results support the hypothesis that anthropogenic resources contribute to increasing raven numbers via increased juvenile survival to departure as well as increased postdeparture survival. We expect raven numbers to grow in concert with the growing human presence in the Mojave Desert unless raven access to anthropogenic resources is diminished

Interbreeding Between Cryptic Lineages of the Common Raven: Evidence for Speciation in Reverse.

Molecular Ecology 20(11):2390-2402.

DNA sequence studies frequently reveal evidence of cryptic lineages in morphologically uniform species, many of which turn out to be evolutionarily distinct species. The Common Raven (Corvus corax) includes two deeply divergent mtDNA lineages: one lineage seems restricted to western North America and the other is Holarctic in distribution. These deep clades hint of the possibility of cryptic species in the western United States. We tested this hypothesis in a population consisting of an equal proportion of both mtDNA clades, by quantifying mating patterns and associated fitness consequences with respect to mtDNA. We also tested for morphological, behavioural and ecological correlates of sex and mtDNA clade membership. Mate pairings were random with respect to mtDNA clades, and there were no differences in reproductive success between assortatively and nonassortatively mated pairs. We found no differences in survival or resource use between clades. There were no differences in morphological or behavioural characters between mtDNA clades, except one clade trended towards greater mobility. These results suggest there are no barriers to gene flow between mtDNA clades and argue that the mtDNA clades have remerged in this population, likely due to a lack of ecological or signal differentiation between individuals in each lineage. Hence, in Common Ravens, phylogeographic structure in mtDNA is a reflection of likely past isolation rather than currently differentiated species.

Differences in space use by Common Ravens in relation to sex, breeding status and kinship

The Condor 114(3):1-11.

Group differences in avian space use relate to group differences in resource use and demographic parameters. However, studies that consider year-round, intraspecific variation in the space use of noncooperatively breeding species are relatively rare. A greater understanding of factors relating to intraspecific variation in space use is especially important for managing human-subsidized predators, such as the Common Raven (Corvus corax). We hypothesized that sex, sociality, and the distribution of bonanzas of food should influence year-round space use by breeding and nonbreeding Common Ravens on the Olympic Peninsula of Washington State. We detected differences in space use between breeders and nonbreeders but not between the sexes. Breeders shared little space with their neighbors and displayed strong site fidelity, except in the fall and winter or after the death of a mate, when some breeding ravens moved extensively. Nonbreeders moved widely, were more gregarious, and their home ranges intersected a greater proportion of communal food resources than did those of breeders. Breeders shared little space with their adult neighbors, but they shared more space with nonbreeders when communal food resources fell within their territories. Pair bonds were broken only by the death of a partner, which in some cases was followed by extensive movements by the surviving adult prior to pairing with a new mate or settling in a new breeding territory. This study is the first to consider the space use of both nonbreeding and breeding Common Ravens in the same population simultaneously

Movements of juvenile Common Ravens in an arid landscape.

Journal of Wildlife Management 73(1):72-81.

Movement patterns of juvenile birds are poorly understood, yet critically important ecological henomena, especially for species with a prolonged juvenile period. We evaluated postfledging movements of juvenile common ravens (Corvus corax) in a western Mojave Desert landscape composed of a mosaic of natural and anthropogenic elements. Generally, ravens do not begin breeding until after their fourth year. We marked 2 annual cohorts of juvenile ravens and followed them from dispersal from their natal territory for up to 33 months. Movements of juvenile common ravens were similar for males and females. Conspecifics and confined livestock feeding operations represented important resources for juvenile ravens, and juveniles were rarely located in open desert. However, initial movements from the natal territory to the nearest communal point subsidy rather than the closest anthropogenic resource suggested juvenile dispersal was influenced by the combination of conspecifics and anthropogenic resources, rather than the distribution of those resources. Land managers concerned with growing raven populations should reduce access to concentrated anthropogenic resources such as landfills and dairies, which serve as important resources for juveniles. Because juvenile ravens rarely venture into open desert, reducing their numbers by lethal removal or other means is unlikely to lessen raven predation of desert tortoises (Gopherus agassizii).

Linking resource use with demographic parameters in a synanthropic population of Common Ravens.

Biological Conservation 144:2264-2273.

A thorough understanding of a population’s ecology requires knowledge of the relationship between habitat use, resource use and demographic parameters. We undertook an empirical investigation of habitat use, resource use and demography in a population of common ravens (Corvus corax), a species widely distributed throughout the Northern Hemisphere. The abundance of ravens is increasing in many parts of western North America, which represents a conservation concern since predation by ravens is thought to contribute to the decline of several sensitive species. We defined resources as the suite of physical and biological components in the environment that led to occupancy of a particular place by ravens. The home ranges of breeding and nonbreeding ravens contained similar proportions of resources, but breeding ravens used more edges, roads, forest, clearcuts, and towns than nonbreeders. We detected no differences in survival between the sexes, but breeding ravens survived at higher rates than nonbreeders, due to exclusion by breeding ravens from those resources positively associated with survival. Raven use of mature forests and anthropogenic land use types was positively associated with survival. Breeding raven use of clearcuts and patchy areas contributed to increased reproduction, but the use of clearcuts along with the use of roads was negatively associated with survival due to illegal shooting. Greater insight into the demography of synanthropic species such as the common raven will enable managers to make informed decisions for protecting biodiversity. This study is the first to consider the demographic consequences of habitat use and resource use for both nonbreeding and breeding common ravens.

Comparative analysis of knowledge representation and reasoning requirements across a range of life sciences textbooks

Journal of Biomedical Semantics 5: 51.

Using knowledge representation for biomedical projects is now commonplace. In previous work, we represented the knowledge found in a college-level biology textbook in a fashion useful for answering questions. We showed that embedding the knowledge representation and question-answering abilities in an electronic textbook helped to engage student interest and improve learning. A natural question that arises from this success, and this paper’s primary focus, is whether a similar approach is applicable across a range of life science textbooks. To answer that question, we considered four different textbooks, ranging from a below-introductory college biology text to an advanced, graduate-level neuroscience textbook. For these textbooks, we investigated the following questions: (1) To what extent is knowledge shared between the different textbooks? (2) To what extent can the same upper ontology be used to represent the knowledge found in different textbooks? (3) To what extent can the questions of interest for a range of textbooks be answered by using the same reasoning mechanisms?

Common Raven juvenile survival in a human-augmented landscape.

Condor 106:517-528.

Anthropogenic resource subsidies have contributed to the dramatic increase in the abundance of Common Ravens (Corvus corax) in the western Mojave Desert, California, during the past 30 years. To better understand the effects of these subsidies on raven demography, we examined whether survival to juvenile departure from the natal territory could be predicted by a set of environmental and morphological variables, such as nest proximity to anthropogenic resources and juvenile condition. We captured 240 juvenile ravens over 2 years and marked them prior to fledging. Nest proximity to anthropogenic resources and earlier fledging dates significantly predicted raven juvenile survival to departure from the natal territory. The best-fitting mark-recapture models predicted postdeparture survival as a function of time since fledging, nest proximity to anthropogenic resources, and year hatched. The positive effect of nest proximity to anthropogenic resources influenced postdeparture survival for at least 9 months after fledging, as revealed by the mark-recapture analysis. Annual survival was 47% for first-year, 81% for second-year, and 83% for third-year birds. Our results support the hypothesis that anthropogenic resources contribute to increasing raven numbers via increased juvenile survival to departure as well as increased postdeparture survival. We expect raven numbers to grow in concert with the growing human presence in the Mojave Desert unless raven access to anthropogenic resources is diminished

Interbreeding Between Cryptic Lineages of the Common Raven: Evidence for Speciation in Reverse.

Molecular Ecology 20(11):2390-2402.

DNA sequence studies frequently reveal evidence of cryptic lineages in morphologically uniform species, many of which turn out to be evolutionarily distinct species. The Common Raven (Corvus corax) includes two deeply divergent mtDNA lineages: one lineage seems restricted to western North America and the other is Holarctic in distribution. These deep clades hint of the possibility of cryptic species in the western United States. We tested this hypothesis in a population consisting of an equal proportion of both mtDNA clades, by quantifying mating patterns and associated fitness consequences with respect to mtDNA. We also tested for morphological, behavioural and ecological correlates of sex and mtDNA clade membership. Mate pairings were random with respect to mtDNA clades, and there were no differences in reproductive success between assortatively and nonassortatively mated pairs. We found no differences in survival or resource use between clades. There were no differences in morphological or behavioural characters between mtDNA clades, except one clade trended towards greater mobility. These results suggest there are no barriers to gene flow between mtDNA clades and argue that the mtDNA clades have remerged in this population, likely due to a lack of ecological or signal differentiation between individuals in each lineage. Hence, in Common Ravens, phylogeographic structure in mtDNA is a reflection of likely past isolation rather than currently differentiated species.

Differences in space use by Common Ravens in relation to sex, breeding status and kinship

The Condor 114(3):1-11.

Group differences in avian space use relate to group differences in resource use and demographic parameters. However, studies that consider year-round, intraspecific variation in the space use of noncooperatively breeding species are relatively rare. A greater understanding of factors relating to intraspecific variation in space use is especially important for managing human-subsidized predators, such as the Common Raven (Corvus corax). We hypothesized that sex, sociality, and the distribution of bonanzas of food should influence year-round space use by breeding and nonbreeding Common Ravens on the Olympic Peninsula of Washington State. We detected differences in space use between breeders and nonbreeders but not between the sexes. Breeders shared little space with their neighbors and displayed strong site fidelity, except in the fall and winter or after the death of a mate, when some breeding ravens moved extensively. Nonbreeders moved widely, were more gregarious, and their home ranges intersected a greater proportion of communal food resources than did those of breeders. Breeders shared little space with their adult neighbors, but they shared more space with nonbreeders when communal food resources fell within their territories. Pair bonds were broken only by the death of a partner, which in some cases was followed by extensive movements by the surviving adult prior to pairing with a new mate or settling in a new breeding territory. This study is the first to consider the space use of both nonbreeding and breeding Common Ravens in the same population simultaneously

Movements of juvenile Common Ravens in an arid landscape.

Journal of Wildlife Management 73(1):72-81.

Movement patterns of juvenile birds are poorly understood, yet critically important ecological henomena, especially for species with a prolonged juvenile period. We evaluated postfledging movements of juvenile common ravens (Corvus corax) in a western Mojave Desert landscape composed of a mosaic of natural and anthropogenic elements. Generally, ravens do not begin breeding until after their fourth year. We marked 2 annual cohorts of juvenile ravens and followed them from dispersal from their natal territory for up to 33 months. Movements of juvenile common ravens were similar for males and females. Conspecifics and confined livestock feeding operations represented important resources for juvenile ravens, and juveniles were rarely located in open desert. However, initial movements from the natal territory to the nearest communal point subsidy rather than the closest anthropogenic resource suggested juvenile dispersal was influenced by the combination of conspecifics and anthropogenic resources, rather than the distribution of those resources. Land managers concerned with growing raven populations should reduce access to concentrated anthropogenic resources such as landfills and dairies, which serve as important resources for juveniles. Because juvenile ravens rarely venture into open desert, reducing their numbers by lethal removal or other means is unlikely to lessen raven predation of desert tortoises (Gopherus agassizii).

Ad libitum water source for a Common Raven.

Wilson Journal of Ornithology 121(1):210-212.

We report a Common Raven (Corvus corax) that learned to turn on a water faucet in a campground at Death Valley National Park, Inyo County, California, USA, and drink from it. Ad libitum availability of water has important implications for survival and reproductive success of desert birds. Ravens commonly exploit anthropogenic sources of water and food; these behaviors are of interest because ravens can be important predators of the federally-threatened desert tortoise (Gopherus agassizii). Our observation is further evidence of the resourcefulness of ravens and challenges involved in limiting access to anthropogenic resources for an intelligent, subsidized predator.

Linking resource use with demographic parameters in a synanthropic population of Common Ravens.

Biological Conservation 144:2264-2273.

A thorough understanding of a population’s ecology requires knowledge of the relationship between habitat use, resource use and demographic parameters. We undertook an empirical investigation of habitat use, resource use and demography in a population of common ravens (Corvus corax), a species widely distributed throughout the Northern Hemisphere. The abundance of ravens is increasing in many parts of western North America, which represents a conservation concern since predation by ravens is thought to contribute to the decline of several sensitive species. We defined resources as the suite of physical and biological components in the environment that led to occupancy of a particular place by ravens. The home ranges of breeding and nonbreeding ravens contained similar proportions of resources, but breeding ravens used more edges, roads, forest, clearcuts, and towns than nonbreeders. We detected no differences in survival between the sexes, but breeding ravens survived at higher rates than nonbreeders, due to exclusion by breeding ravens from those resources positively associated with survival. Raven use of mature forests and anthropogenic land use types was positively associated with survival. Breeding raven use of clearcuts and patchy areas contributed to increased reproduction, but the use of clearcuts along with the use of roads was negatively associated with survival due to illegal shooting. Greater insight into the demography of synanthropic species such as the common raven will enable managers to make informed decisions for protecting biodiversity. This study is the first to consider the demographic consequences of habitat use and resource use for both nonbreeding and breeding common ravens.

Comparative analysis of knowledge representation and reasoning requirements across a range of life sciences textbooks

Journal of Biomedical Semantics 5: 51.

Using knowledge representation for biomedical projects is now commonplace. In previous work, we represented the knowledge found in a college-level biology textbook in a fashion useful for answering questions. We showed that embedding the knowledge representation and question-answering abilities in an electronic textbook helped to engage student interest and improve learning. A natural question that arises from this success, and this paper’s primary focus, is whether a similar approach is applicable across a range of life science textbooks. To answer that question, we considered four different textbooks, ranging from a below-introductory college biology text to an advanced, graduate-level neuroscience textbook. For these textbooks, we investigated the following questions: (1) To what extent is knowledge shared between the different textbooks? (2) To what extent can the same upper ontology be used to represent the knowledge found in different textbooks? (3) To what extent can the questions of interest for a range of textbooks be answered by using the same reasoning mechanisms?

Common Raven juvenile survival in a human-augmented landscape.

Condor 106:517-528.

Anthropogenic resource subsidies have contributed to the dramatic increase in the abundance of Common Ravens (Corvus corax) in the western Mojave Desert, California, during the past 30 years. To better understand the effects of these subsidies on raven demography, we examined whether survival to juvenile departure from the natal territory could be predicted by a set of environmental and morphological variables, such as nest proximity to anthropogenic resources and juvenile condition. We captured 240 juvenile ravens over 2 years and marked them prior to fledging. Nest proximity to anthropogenic resources and earlier fledging dates significantly predicted raven juvenile survival to departure from the natal territory. The best-fitting mark-recapture models predicted postdeparture survival as a function of time since fledging, nest proximity to anthropogenic resources, and year hatched. The positive effect of nest proximity to anthropogenic resources influenced postdeparture survival for at least 9 months after fledging, as revealed by the mark-recapture analysis. Annual survival was 47% for first-year, 81% for second-year, and 83% for third-year birds. Our results support the hypothesis that anthropogenic resources contribute to increasing raven numbers via increased juvenile survival to departure as well as increased postdeparture survival. We expect raven numbers to grow in concert with the growing human presence in the Mojave Desert unless raven access to anthropogenic resources is diminished

Interbreeding Between Cryptic Lineages of the Common Raven: Evidence for Speciation in Reverse.

Molecular Ecology 20(11):2390-2402.

DNA sequence studies frequently reveal evidence of cryptic lineages in morphologically uniform species, many of which turn out to be evolutionarily distinct species. The Common Raven (Corvus corax) includes two deeply divergent mtDNA lineages: one lineage seems restricted to western North America and the other is Holarctic in distribution. These deep clades hint of the possibility of cryptic species in the western United States. We tested this hypothesis in a population consisting of an equal proportion of both mtDNA clades, by quantifying mating patterns and associated fitness consequences with respect to mtDNA. We also tested for morphological, behavioural and ecological correlates of sex and mtDNA clade membership. Mate pairings were random with respect to mtDNA clades, and there were no differences in reproductive success between assortatively and nonassortatively mated pairs. We found no differences in survival or resource use between clades. There were no differences in morphological or behavioural characters between mtDNA clades, except one clade trended towards greater mobility. These results suggest there are no barriers to gene flow between mtDNA clades and argue that the mtDNA clades have remerged in this population, likely due to a lack of ecological or signal differentiation between individuals in each lineage. Hence, in Common Ravens, phylogeographic structure in mtDNA is a reflection of likely past isolation rather than currently differentiated species.

Differences in space use by Common Ravens in relation to sex, breeding status and kinship

The Condor 114(3):1-11.

Group differences in avian space use relate to group differences in resource use and demographic parameters. However, studies that consider year-round, intraspecific variation in the space use of noncooperatively breeding species are relatively rare. A greater understanding of factors relating to intraspecific variation in space use is especially important for managing human-subsidized predators, such as the Common Raven (Corvus corax). We hypothesized that sex, sociality, and the distribution of bonanzas of food should influence year-round space use by breeding and nonbreeding Common Ravens on the Olympic Peninsula of Washington State. We detected differences in space use between breeders and nonbreeders but not between the sexes. Breeders shared little space with their neighbors and displayed strong site fidelity, except in the fall and winter or after the death of a mate, when some breeding ravens moved extensively. Nonbreeders moved widely, were more gregarious, and their home ranges intersected a greater proportion of communal food resources than did those of breeders. Breeders shared little space with their adult neighbors, but they shared more space with nonbreeders when communal food resources fell within their territories. Pair bonds were broken only by the death of a partner, which in some cases was followed by extensive movements by the surviving adult prior to pairing with a new mate or settling in a new breeding territory. This study is the first to consider the space use of both nonbreeding and breeding Common Ravens in the same population simultaneously

Movements of juvenile Common Ravens in an arid landscape.

Journal of Wildlife Management 73(1):72-81.

Movement patterns of juvenile birds are poorly understood, yet critically important ecological henomena, especially for species with a prolonged juvenile period. We evaluated postfledging movements of juvenile common ravens (Corvus corax) in a western Mojave Desert landscape composed of a mosaic of natural and anthropogenic elements. Generally, ravens do not begin breeding until after their fourth year. We marked 2 annual cohorts of juvenile ravens and followed them from dispersal from their natal territory for up to 33 months. Movements of juvenile common ravens were similar for males and females. Conspecifics and confined livestock feeding operations represented important resources for juvenile ravens, and juveniles were rarely located in open desert. However, initial movements from the natal territory to the nearest communal point subsidy rather than the closest anthropogenic resource suggested juvenile dispersal was influenced by the combination of conspecifics and anthropogenic resources, rather than the distribution of those resources. Land managers concerned with growing raven populations should reduce access to concentrated anthropogenic resources such as landfills and dairies, which serve as important resources for juveniles. Because juvenile ravens rarely venture into open desert, reducing their numbers by lethal removal or other means is unlikely to lessen raven predation of desert tortoises (Gopherus agassizii).

Ad libitum water source for a Common Raven.

Wilson Journal of Ornithology 121(1):210-212.

We report a Common Raven (Corvus corax) that learned to turn on a water faucet in a campground at Death Valley National Park, Inyo County, California, USA, and drink from it. Ad libitum availability of water has important implications for survival and reproductive success of desert birds. Ravens commonly exploit anthropogenic sources of water and food; these behaviors are of interest because ravens can be important predators of the federally-threatened desert tortoise (Gopherus agassizii). Our observation is further evidence of the resourcefulness of ravens and challenges involved in limiting access to anthropogenic resources for an intelligent, subsidized predator.

First record of double-brooding for the Common Raven (Corvus corax).

Western Birds 33(4):258-261.