Papers by John Rotenberry
Behavioral Ecology, 2014
The adrenocortical stress response may divert energy away from sexual ornamentation, such that or... more The adrenocortical stress response may divert energy away from sexual ornamentation, such that ornaments signal exposure or resistance to physiological stress. Alternatively, steroid glucocorticoids released via the stress response may support ornament development by stimulating foraging and metabolism. The relationship between glucocorticoids and ornamentation may vary with ornament type and across age and sex classes that experience different resource allocation tradeoffs. In yellow warblers (Setophaga petechia), we conducted the first study to simultaneously assess whether relationships between corticosterone (the primary avian glucocorticoid) and ornamentation depend on sexual pigment type, age, and sex. We quantified carotenoid-and phaeomelanin-based pigmentation using spectrometry, and assayed corticosterone in feathers (CORT f ) to derive an integrative metric of corticosterone levels during molt. Yellow warblers with lower carotenoid hue (lambda R50) had higher CORT f , suggesting that carotenoid hue may signal stress during molt across age and sex classes. Carotenoid chroma also negatively correlated with CORT f . However, this correlation was absent in older males, seemingly because these males display more saturated carotenoid pigmentation, and thus less variance in carotenoid chroma. Young males with higher CORT f also tended to have poorer quality tertial feathers, indicating poor condition at molt. Phaeomelanin-based pigmentation was largely unrelated to CORT f , suggesting that pleiotropic effects do not link phaeomelanogenesis and CORT release. Finally, CORT f was repeatable across years within individuals. Thus, carotenoid-and phaeomelanin-based pigmentation communicate nonequivalent information about physiological stress, with carotenoid pigmentation having the potential to signal stable differences in stress levels that could affect fitness.
Journal of Arid Environments, 2015
ABSTRACT We investigated the influence of landscape characteristics on avian species occupancy in... more ABSTRACT We investigated the influence of landscape characteristics on avian species occupancy in riparian forests embedded in a matrix of urban and agricultural land use in a semiarid region of the Southwestern US. We conducted bird and vegetation (local-scale characteristics) surveys within 196 50-m radius sample points in 10 riparian forests in southern California. We quantified landscape composition within a 500 m-radius surrounding each point. For each species we developed 8 single-season occupancy models using principal components summarizing local- and landscape-scale characteristics and a spatial autocovariate as covariates. Of 21 species analyzed, occupancy by 11 was associated with landscape characteristics, by 6 with local vegetation characteristics, by 3 with both local and landscape characteristics, and by 1 with none. Five species positively responded to surrounding urban development (2 negative), whereas 4 negatively responded to agricultural land (1 positive). The amount of riparian forests had a strong positive effect on the occurrence of riparian obligates. Our results emphasize the importance of landscape characteristics on species occupancy patterns in riparian systems although relationships were also species-specific. Our results imply a positive effect of urbanization compared to agricultural land uses in this region, most likely due to enhanced vegetation development.
In southern California, the Red Diamond Rattlesnake (Crotalus ruber) occupies a region with one
Journal of Avian Biology
ABSTRACT
Background/Question/Methods Habitat selection is an ecological trait shaped by natural selection.... more Background/Question/Methods Habitat selection is an ecological trait shaped by natural selection. Animals should select habitats that optimize individual fitness, in which case habitat selection is “adaptive.” However, the adaptive significance of habitat selection may be difficult to document in nature, particularly for populations within which all members occupy an “adaptive peak,” i.e., a range of habitats among which expressed relative fitness is uniform because the phenotypic variation in habitat choice necessary to detect habitat-fitness relationships no longer exists naturally. With this problem in mind, we investigated the adaptive significance of nest site selection in a population of Yellow Warblers. Given the general importance of nest predation to avian fitness, we specifically investigated nest site selection in the context of predation risk. We focused on site selection with respect to nest concealment, because despite being mechanistically relevant to nest predation, ...
Journal of Avian Biology, 2014
ABSTRACT Adult-directed predation risk imposes important behavioral constraints on parents and mi... more ABSTRACT Adult-directed predation risk imposes important behavioral constraints on parents and might thus alter relationships between costly sexual ornaments and parental performance. For instance, under low predation risk, highly ornamented individuals might display better parental performance than others, as predicted by ‘good parent’ models of sexual selection. However, under high risk of predation, highly ornamented individuals might abandon parental effort if conspicuous to predators, or if social partners are more willing to take parental risks when paired with highly ornamented mates. We experimentally elevated perceived adult-directed predation risk near nests to explore how carotenoid- and phaeomelanin-based pigmentation in both sexes relate to parental risk-taking for offspring in the yellow warbler Setophaga petechia. Compared to other males, males with more intense carotenoid-based pigmentation maintained higher levels of paternal effort under predation risk at highly concealed nests, but reduced nestling provisioning rate more at exposed nests. Further, when faced with predation risk, females with more phaeomelanin-based pigmentation reduced nestling provisioning rate less than other females, regardless of nest concealment. Females displayed higher parental effort across treatments when paired to males with more colorful carotenoid pigmentation. However, birds did not reduce parental effort under risk less when paired to a highly ornamented mate, suggesting that predation risk did not accentuate differential allocation. Males did not take fewer parental risks than females. Results indicate that nest concealment modifies parental risk-taking by males with colorful carotenoid-based pigmentation, and suggest that female melanin-based pigmentation may indicate boldness and greater a propensity to take parental risks.
Journal of Avian Biology, 2014
In urban habitats, organisms face unique fi tness challenges including disturbance from human act... more In urban habitats, organisms face unique fi tness challenges including disturbance from human activity and noise. One physiological mechanism that may be plastically or evolutionarily modifi ed to ameliorate deleterious eff ects of anthropogenic disturbance is the adrenocortical stress response. Individuals in urban environments may display smaller stress responses, which may prevent pathologies associated with consistent elevation of stress hormones, and may also show diff erences in baseline corticosterone (CORT, the primary avian stress hormone), due to altered energetic demands or chronic stress. We examined whether stress physiology and condition metrics in male song sparrows Melospiza melodia vary as a function of discrete diff erences in anthropogenic disturbance level (activity centers and refuges) or with continuous variation in an urbanization score and noise environment. Males breeding in activity centers displayed lower maximal (acute) CORT levels than activity refuge males, and acute CORT also tended to negatively correlate with urbanization score. Baseline CORT did not diff er between habitat types, and activity center males also showed no evidence of changes in body mass, hematocrit, or antioxidant capacity. Further, activity center males had higher quality feathers (indicative of higher condition at molt) than activity refuge males. We found no indication that the noise environment altered stress physiology or condition in song sparrows. Overall, results suggest that song sparrows are an urban adapter species, which are not detrimentally aff ected by unique selective pressures encountered in the urban environment.
Pollination syndromes' are suites of phenotypic traits hypothesized to reflect convergent adaptat... more Pollination syndromes' are suites of phenotypic traits hypothesized to reflect convergent adaptations of flowers for pollination by specific types of animals. They were first developed in the 1870s and honed during the mid 20th Century. In spite of this long history and their central role in organizing research on plant -pollinator interactions, the pollination syndromes have rarely been subjected to test. The syndromes were tested here by asking whether they successfully capture patterns of covariance of floral traits and predict the most common pollinators of flowers. † Methods Flowers in six communities from three continents were scored for expression of floral traits used in published descriptions of the pollination syndromes, and simultaneously the pollinators of as many species as possible were characterized. † Key Results Ordination of flowers in a multivariate 'phenotype space' defined by the syndromes showed that almost no plant species fall within the discrete syndrome clusters. Furthermore, in approximately two-thirds of plant species, the most common pollinator could not be successfully predicted by assuming that each plant species belongs to the syndrome closest to it in phenotype space. † Conclusions The pollination syndrome hypothesis as usually articulated does not successfully describe the diversity of floral phenotypes or predict the pollinators of most plant species. Caution is suggested when using pollination syndromes for organizing floral diversity, or for inferring agents of floral adaptation. A fresh look at how traits of flowers and pollinators relate to visitation and pollen transfer is recommended, in order to determine whether axes can be identified that describe floral functional diversity more successfully than the traditional syndromes.
The Birds of North America Online, 1999
Wildlife Society Bulletin, 2012
To guide monitoring of burrowing owls (Athene cunicularia) in the Coachella Valley, California, U... more To guide monitoring of burrowing owls (Athene cunicularia) in the Coachella Valley, California, USA, we analyzed survey-method-specific seasonal variation in detectability. Point-based call-broadcast surveys yielded high early season detectability that then declined through time, whereas detectability on driving surveys increased through the season. Point surveys without call-broadcasts yielded the lowest detectability rates overall. To maximize detectability, we recommend coupling early season pointbased call-broadcast surveys with late-season driving surveys. Occupancy models proved useful for integrating data from multiple methods to analyze distributional patterns while accounting for variation in detectability. ß 2012 The Wildlife Society.
The American Naturalist, 1985
Oikos, 1987
JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, a... more JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. . Wiley and Nordic Society Oikos are collaborating with JSTOR to digitize, preserve and extend access to Oikos. . 1987. Habitat occupancy patterns of North American shrubsteppe birds: the effects of spatial scale. -Oikos 48: 132-147.
Oikos, 2011
... An 'ecological trap' for yellow warbler nest microhabitat s... more ... An 'ecological trap' for yellow warbler nest microhabitat selection. Quresh S. Latif,; Sacha K. Heath,; John T. Rotenberry. ... We used an a priori information-theoretic approach (Burnham and Anderson 2002) to analyze whether the data supported preference–survival effects. ...
Oecologia, 1987
We documented patterns of activity and microhabitat use by breeding male Sage Sparrows (Amphispiz... more We documented patterns of activity and microhabitat use by breeding male Sage Sparrows (Amphispiza belli) and Brewer's Sparrows (Spizella breweri) in the semiarid shrubsteppe of northwestern U.S.A. to determine how their behavior varies in space and time and how these variations relate to environmental features. In analyses of several sites with multiple plots that were studied for 2-4 yr, the frequencies of activities and substrate use varied significantly with year, plot, and location. The major activities, foraging and singing, varied inversely with one another. Thus, although the general structure of the activity budgets of these species was stable (i.e. foraging and singing were always the most frequent activities), there was considerable variation in the quantitative details of their behavior in space and time. Using stepwise regression, we related these variations in behavior to variations in environmental features such as the densities of the same or other species, the number of species in the community, and coverages of the different substrate types. Few patterns emerged, and those that did were generally not in accord with our expectations. In particular, patterns of substrate use were not related to variations in coverages of those substrates. Sage Sparrows, for example, increased their use of sagebrush and grass with increasing grass coverage and with increasing densities of Sage Sparrows. Responses to both variables suggested nonlinear threshold patterns.
Oecologia, 1999
Jutta C. Burger á Michael A. Patten John T. Rotenberry á Richard A. Redak ... tivity (MacArthur a... more Jutta C. Burger á Michael A. Patten John T. Rotenberry á Richard A. Redak ... tivity (MacArthur and Pianka 1966; Hespenheide 1971), habitat selection (Beaver and Baldwin 1975), population size (Crawford and Jennings 1989), migrant numbers (Griscom 1950), and ...
Journal of Wildlife Management, 2009
ABSTRACT ABSTRACT Movement patterns of juvenile birds are poorly understood, yet critically impo... more ABSTRACT ABSTRACT Movement patterns of juvenile birds are poorly understood, yet critically important ecological phenomena, 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).
Journal of the North American Benthological Society, 1988
The Journal of Ecology, 1987
Journal of Biogeography, 2011
ABSTRACT Aim Local-scale processes at species distribution margins can affect larger-scale distri... more ABSTRACT Aim Local-scale processes at species distribution margins can affect larger-scale distribution dynamics, but are rarely studied. The objective of this research was to elucidate the nature of distribution limits by studying the comparative structure, dynamics and environmental associations of breeding bird populations at their distribution margin. We hypothesized that climate is principally responsible for setting distribution limits, whereas biotic habitat features are more strongly associated with distribution patterns within the range. Location Southern California, USA. Methods During 2005–2007 we studied the distribution patterns of breeding birds in three study areas, each spanning a low-elevation (200–1800 m) desert scrub-to-chaparral gradient. We used logistic regression with hierarchical partitioning to assess the independent effects of environmental variables (e.g. climate versus habitat) on distributions. We tested for shifts in the relative importance of these environmental variables in determining distribution limits versus within-range patterns, and we also compared higher- and lower-elevation groups of species. Results Distribution patterns were highly variable among species, but were remarkably static over the three study areas and 3-year study period. Across species, habitat floristic variables performed relatively well at explaining distribution patterns. For higher-elevation species (chaparral birds), climate was relatively important in setting their lower distribution limits, and there was a shift to a greater importance of biotic habitat (mainly habitat structural variables) for determining within-range patterns. Relationships were more mixed for lower-elevation species (desert scrub birds), but with respect to distribution limits, biotic habitat variables tended to be more important relative to climate than we observed for chaparral birds. Main conclusions Along this warm, arid elevational gradient, higher-elevation chaparral birds are more limited by climate at their lower margin than are lower-elevation desert birds at their upper margin, suggesting that climate plays a strong role (relative to other values) in excluding non-desert birds from desert. However, given the strong differences among species, predictive distribution models will need to be individually tailored, and for most species biotic habitat variables were of greater importance than climate in determining limits. This research highlights the usefulness of studying environmental relationships at distribution margins and the importance of considering biotic relationships in forecasting distribution shifts under changing climates.
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Papers by John Rotenberry