John C Wingfield

University of California, Davis, Davis, California, United States

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Publications (393)1084.11 Total impact

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    ABSTRACT: Seabirds often have high loads of contaminants. These contaminants have endocrine disrupting properties but their relationships with some endocrine mechanisms are still poorly investigated in free-living organisms. This is the case for the stress response which shifts energy investment away from reproduction and redirects it towards survival. In birds, this stress response is achieved through a release of corticosterone and is also accompanied by a decrease in circulating prolactin, an anterior pituitary hormone widely involved in regulating parental cares. We measured blood concentrations of some legacy persistent organic pollutants (POPs) and mercury (Hg) and examined their relationships with the corticosterone and prolactin responses of known-age (9–46 years old) incubating snow petrels (Pagodroma nivea) to a standardized capture/handling stress protocol. In this Antarctic seabird, we also investigated whether high contaminant burden correlates with a higher occurrence of egg neglect, a frequently observed behavior in snow petrels. POPs and Hg were unrelated to age. Stress-induced corticosterone concentrations were positively related to POPs in both sexes, and stress-induced prolactin concentrations were negatively related to Hg in males. Egg-neglect behavior was not related to POPs burden, but males with higher Hg concentrations were more likely to neglect their egg. This suggests that in birds, relationships between age and contaminants are complex and that even low to moderate concentrations of POPs and Hg are significantly related to hormonal secretion. In this Antarctic species, exposure to legacy POPs and Hg could make individuals more susceptible to environmental stressors such as ongoing disturbances in Polar Regions.
    Science of The Total Environment 02/2015; 505:180-188. · 3.16 Impact Factor
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    ABSTRACT: The hormonal stress response is flexible and can be modulated by individuals according to its costs and benefits. Therefore, it is predicted that parents in poor body condition should modify their hormonal stress response, and thus, redirect energy allocation processes from parental care to self-maintenance when stressors occur. To test this prediction, most studies on free-living vertebrates have only focused on the stress response while the stress recovery – how quickly hormonal levels return to baseline values - has been neglected. Moreover, most studies have only focused on corticosterone –the primary mediator of allostasis - without paying attention to prolactin despite its major role in mediating parental behaviours. Here, we examined the effect of a short-term fasting event on the corticosterone and prolactin stress responses and recoveries, and we subsequently explored their relationships with parental decision in the snow petrel (Pagadroma nivea). By comparing the hormonal profiles of fasting and non-fasting snow petrels, we showed that parents modulate their corticosterone (but not prolactin) stress response according to their energetic status. We also described for the first time the hormonal stress recoveries in wild birds and found that they did not differ between fasting and non-fasting birds. Importantly, egg neglect was negatively correlated with circulating prolactin but not corticosterone levels in this species, demonstrating therefore a complex link between body condition, parental behavior and circulating corticosterone and prolactin levels. We suggest that both corticosterone and prolactin play a major role in the way parents adjust to stressors. This multiple signaling may allow parents to fine-tune their response to stressor, and especially, to activate specific allostasis-related mechanisms in a timely manner.
    Hormones and Behavior 01/2015; 67:28-37. · 3.74 Impact Factor
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    ABSTRACT: Seabirds often have high loads of contaminants. These contaminants have endocrine disrupting properties but their relationships with some endocrine mechanisms are still poorly investigated in free-living organisms. This is the case for the stress response which shifts energy investment away from reproduction and redirects it towards survival. In birds, this stress response is achieved through a release of corticosterone and is also accompanied by a decrease in circulating prolactin, an anterior pituitary hormone widely involved in regulating parental cares. We measured blood concentrations of some legacy persistent organic pollutants (POPs) and mercury (Hg) and examined their relationships with the corticosterone and prolactin responses of known-age (9–46 years old) incubating snow petrels (Pagodroma nivea) to a standardized capture/handling stress protocol. In this Antarctic seabird, we also investigated whether high contaminant burden correlates with a higher occurrence of egg neglect, a frequently observed behavior in snow petrels. POPs and Hg were unrelated to age. Stress-induced corticosterone concentrations were positively related to POPs in both sexes, and stress-induced prolactin concentrations were negatively related to Hg in males. Egg-neglect behavior was not related to POPs burden, but males with higher Hg concentrations were more likely to neglect their egg. This suggests that in birds, relationships between age and contaminants are complex and that even low to moderate concentrations of POPs and Hg are significantly related to hormonal secretion. In this Antarctic species, exposure to legacy POPs and Hg could make individuals more susceptible to environmental stressors such as ongoing disturbances in Polar Regions.
    Science of The Total Environment 01/2015; 505:180–188. · 3.16 Impact Factor
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    ABSTRACT: The physical and biological responses to rapid arctic warming are proving acute, and as such, there is a need to monitor, understand, and predict ecological responses over large spatial and temporal scales. The use of the Normalized Difference Vegetation Index (NDVI) acquired from airborne and satellite sensors addresses this need as it is widely used as a tool for detecting and quantifying spatial and temporal dynamics of tundra vegetation cover, productivity, and phenology. Such extensive use of the NDVI to quantify vegetation characteristics suggests that it may be similarly applied to characterizing primary and secondary consumer communities. Here we develop empirical models to predict canopy arthropod biomass with canopy-level measurements of the NDVI both across and within distinct tundra vegetation communities over four growing seasons in the arctic foothills region of the Brooks Range, Alaska. When canopy arthropod biomass is predicted with the NDVI across all four growing seasons, our overall model that includes all four vegetation communities explains 63% of the variance in canopy arthropod biomass. Whereas each of our four vegetation community-specific models explain 74% (moist tussock tundra), 82% (erect shrub tundra), 84% (riparian shrub tundra), and 87% (dwarf shrub tundra) of the observed variation in canopy arthropod biomass. Our field-based study suggests that measurements of the NDVI made from air and spaceborne sensors may be able to quantify spatial and temporal variation in canopy arthropod biomass at landscape to regional scales.
    Ecological Applications 10/2014; · 3.82 Impact Factor
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    ABSTRACT: Climate warming is affecting the Arctic in multiple ways, including via increased dominance of deciduous shrubs. Although many studies have focused on how this vegetation shift is altering nutrient cycling and energy balance, few have explicitly considered effects on tundra fauna, such as the millions of migratory songbirds that breed in northern regions every year. To understand how increasing deciduous shrub dominance may alter breeding songbird habitat, we quantified vegetation and arthropod community characteristics in both graminoid and shrub dominated tundra. We combined measurements of preferred nest site characteristics for Lapland longspurs (Calcarius lapponicus) and Gambel's White-crowned sparrows (Zonotrichia leucophrys gambelii) with modeled predictions for the distribution of plant community types in the Alaskan arctic foothills region for the year 2050. Lapland longspur nests were found in sedge-dominated tussock tundra where shrub height does not exceed 20 cm, whereas White-crowned sparrows nested only under shrubs between 20 cm and 1 m in height, with no preference for shrub species. Shrub canopies had higher canopy dwelling arthropod availability (i.e. small flies and spiders) but lower ground dwelling arthropod availability (i.e. large spiders and beetles). Since flies are the birds’ preferred prey, increasing shrubs may result in a net enhancement in preferred prey availability. Acknowledging the coarse resolution of existing tundra vegetation models, we predict that by 2050 there will be a northward shift in current White-crowned sparrow habitat range and a 20-60% increase in their preferred habitat extent, while Lapland longspur habitat extent will be equivalently reduced. Our findings can be used to make first approximations of future habitat change for species with similar nesting requirements. However, we contend that as exemplified by the current study's findings, existing tundra modeling tools cannot yet simulate the fine-scale habitat characteristics that are critical to accurately predicting future habitat extent for many wildlife species.This article is protected by copyright. All rights reserved.
    Global Change Biology 10/2014; · 8.22 Impact Factor
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  • Wolfgang Goymann, John C. Wingfield
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    ABSTRACT: Testosterone is a key hormone for the development of secondary sexual characters and dimorphisms in behavior and morphology of male vertebrates. Because females often express detectable levels of testosterone, testosterone has been suggested to also play a role in the modulation of secondary sexual traits in females. Previous comparative analyses in birds and fish demonstrated a relationship between male-to-female testosterone ratios and the degree of sexual dimorphism. Furthermore, female maximum testosterone was related to mating system and coloniality. Here, we reevaluate these previous ideas using phylogenetic analyses and effect size measures for the relationship between birds’ male-to-female maximum testosterone levels. Further, we investigate the seasonal androgen response of female birds (the difference from baseline to maximum testosterone), which in males is strongly related to mating system. We could not confirm a relationship between male-to-female testosterone, maximum female testosterone, or the seasonal androgen response of females with any life-history parameter. We conclude that the expectation that testosterone regulates traits in females in a similar manner as in males should be reconsidered. This expectation may be partially due to hormone manipulation studies using pharmacological doses of testosterone that had similar effects in females than in males but may be of limited importance for the physiological range of testosterone concentrations occurring within ecological and evolutionary contexts. Thus, the assumption that circulating testosterone should covary with ecologically relevant secondary sexual traits in females may be misleading: selection pressures on females differ from those on males and females may regulate behavior differently.
    Behavioral Ecology 04/2014; 25(4):685-699. · 3.22 Impact Factor
  • Wolfgang Goymann, John C. Wingfield
    Behavioral Ecology 04/2014; 25(4):704-705. · 3.22 Impact Factor
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    ABSTRACT: Emberizid sparrows (emberizidae) have played a prominent role in the study of avian vocal communication and social behavior. We present here brain transcriptomes for three emberizid model systems, song sparrow Melospiza melodia, white-throated sparrow Zonotrichia albicollis, and Gambel's white-crowned sparrow Zonotrichia leucophrys gambelii. Each of the assemblies covered fully or in part, over 89% of the previously annotated protein coding genes in the zebra finch Taeniopygia guttata, with 16,846, 15,805, and 16,646 unique BLAST hits in song, white-throated and white-crowned sparrows, respectively. As in previous studies, we find tissue of origin (auditory forebrain versus hypothalamus and whole brain) as an important determinant of overall expression profile. We also demonstrate the successful isolation of RNA and RNA-sequencing from post-mortem samples from building strikes and suggest that such an approach could be useful when traditional sampling opportunities are limited. These transcriptomes will be an important resource for the study of social behavior in birds and for data driven annotation of forthcoming whole genome sequences for these and other bird species.
    PeerJ. 01/2014; 2:e396.
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    Jesse S. Krause, David Dorsa, John C. Wingfield
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    ABSTRACT: The aim of this study was to determine circulating patterns of the three major adrenal steroids in blood in response to stress during acute restraint handling in two subspecies of white-crowned sparrow (Zonotrichia leucophrys). Gambel’s white-crowned sparrows (Z.l. gambelii) are long distance migrants that breed at high latitudes and Nuttall’s white-crowned sparrows (Z.l. nuttalli) are residents of coastal California. Column partition chromatography was developed to separate progesterone, dehydroepiandrosterone (DHEA), and corticosterone from a small plasma sample. Each of these steroids has the capability to modulate the stress response through various mechanisms. For example, progesterone is bound to corticosterone binding globulin (CBG) with a higher affinity than corticosterone. If plasma levels of progesterone rise during acute stress, then this could displace corticosterone from CBG and increase the amount of biologically active, free, corticosterone in blood. Dehydroepiandrosterone (DHEA) has been implicated to have many anti-stress properties with the potential to mitigate some of the actions of corticosterone. Results indicate that progesterone levels in both subspecies are elevated in response to acute stress handling. DHEA levels declined in Gambel’s but did not change in Nuttall’s. Thus DHEA does not follow the same secretory pattern as in mammals. Corticosterone levels were elevated in response to acute stress handling in both subspecies. This study provides new insight into an integrated stress response among three steroids.
    Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology. 01/2014;
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    ABSTRACT: Across vertebrates, the hypothalamic-pituitary-adrenal axis is a conserved neuroendocrine network that responds to changing environments and involves the release of glucocorticoids into the blood. Few studies have been carried out concerning mammalian adrenal regulation in wild species either in the laboratory or field, and even fewer have been able to determine true glucocorticoid baselines. We studied the South-American caviomorph rodent Octodon degus, a diurnal and social mammal that has become an important species in the biological research. First, we determined the plasma cortisol baseline and the acute stress concentrations during the non-reproductive and mating seasons in free-living individuals. Second, using the same protocol we assessed the impact of long-term captivity on the adrenal function in wild-caught degus and degus born in laboratory. Third, we examined laboratory groups formed with degus taken from two distant natural populations; one of them originally occurs at the Andes Mountains in high altitude conditions. The data revealed seasonal modulation of basal cortisol in the wild associated with mating. In laboratory, degus presented higher cortisol stress responses, with greater magnitudes shown in degus born and reared in captivity. No differences between populations were found. The results suggest differential regulatory mechanisms between basal and stress-induced cortisol levels, and context dependence of cortisol modulation in a mammalian species.
    General and Comparative Endocrinology 12/2013; · 2.82 Impact Factor
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    ABSTRACT: Background/Aim: Sickness behaviors are the behavioral alterations animals exhibit during the course of an infection, often accompanied by reduced reproductive activity. Adopting sickness behaviors may aid in overcoming the infection, by diverting energy from routine activities towards enhancement of the immune system. Nonetheless, sickness behaviors are plastic, being influenced by specific environmental and social circumstances. Here, we tested whether the presentation of a novel female to males suffering from a simulated infection could impact the behavioral effects of sickness, the reproductive axis, or both. Methods: Male zebra finches were housed in isolation and injected intramuscularly with lipopolysaccharide or saline. Behaviors were recorded before (3 h before injection) and after (3.5 h after injection) addition of a novel female to the cage for 30 min. Four hours after injection, we collected the brain and testis for the analysis of important reproductive axis modulators, gonadotropin-releasing hormone, and gonadotropin-inhibitory hormone, and to quantify gene expression of a proinflammatory cytokine involved in the regulation of sickness behaviors [interleukin (IL)-1β]. Testosterone was quantified in the plasma. Results: The presence of a novel female diminished sickness behaviors and induced alterations in the reproductive axis within 30 min, with no associated changes in brain gene expression of IL-1β. Social environment itself altered brain gene expression of IL-1β. Conclusions: Male zebra finches prioritize the opportunity to mate versus investment in recovery from an infection, as determined by reduced expression of sickness behaviors when a potential mate was present. The behavioral effects of IL-1β appear to be context dependent in this species.
    NeuroImmunoModulation 09/2013; 20(6):348-360. · 1.84 Impact Factor
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  • Frédéric Angelier, John C Wingfield
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    ABSTRACT: In this perspective paper, we emphasize the importance that integrative mechanisms, and especially the GC (glucocorticoid) stress response, can play in the ability of vertebrates to cope with ongoing global change. The GC stress response is an essential mediator of allostasis (i.e. the responses of an organism to a perturbation) that aims at maintaining stability (homeostasis) despite changing conditions. The GC stress response is a complex mechanism that depends on several physiological components and aims at promoting immediate survival at the expense of other life-history components (e.g. reproduction) when a labile perturbation factor (LPF) occurs. Importantly, this mechanism is somewhat flexible and its degree of activation can be adjusted to the fitness costs and benefits that result from the GC stress response. Therefore, this GC stress response mediates life-history decisions and is involved in the regulation of important life-history trade-offs. By inducing abrupt and rapid changes in the regime of LPFs, we believe that global change can affect the efficiency of the GC stress response to maintain homeostasis and to appropriately regulate these trade-offs. This dysfunction may result in an important mismatch between new LPFs and the associated GC stress response and, thus, in the inability of vertebrates to cope with a changing world. In that context, it is essential to better understand how the GC stress response can be adjusted to new LPFs through micro-evolution, phenotypic plasticity and phenotypic flexibility (habituation and sensitization). This paper sets up a theoretical framework, hypotheses and new perspectives that will allow testing and better understanding how the GC stress response can help or constrain individuals, populations and species to adjust to ongoing global change.
    General and Comparative Endocrinology 06/2013; · 2.82 Impact Factor
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    Gang Wang, Marilyn Ramenofsky, John C. Wingfield
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    ABSTRACT: In seasonally breeding birds, the annual cycle of photoperiod is a principal environmental cue for temporal arrangement of different life-history stages, such as migration and breeding. In the past, most research has focused on the mechanisms of photoperiodic control of breeding with less attention paid to migration. In Gambel’s white-crowned sparrow Zonotrichia leucophrys gambelii (GWCS), photoreceptors for induction of breeding are known to reside in the basal hypothalamus. However, it is unknown whether the sites of photoperiodic reception for vernal migration are the same as those for breeding. Therefore, we hypothesized that they may be controlled separately. In this study, we exposed photosensitive GWCSs to low-penetration green light (wavelength at 510 nm) under a regime of 1 lux during the day and <0.1 lux at night, and switched the photoperiodic conditions from short day (10 h daytime) to long day (18 h daytime). The results showed that the experimental birds developed traits associated with vernal migration including mass increase, fat deposition and migratory restlessness behavior when transferred from short day to long day green light cycles, while control birds maintained continuously on short day green light conditions did not express any migration related characteristics. Neither experimental nor control groups showed gonadal recrudescence under either green light cycles. In support of our hypothesis, we were able to apparently dissociate the photoperiodic responses regulating vernal migration and breeding, which suggests separate mechanisms of photoperiodic time measurement. Such distinct photoperiodic mechanisms may drive the fine-tuned temporal arrangement of the two life history stages.
    Current Zoology 06/2013; 59(3):349-359. · 1.81 Impact Factor
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    ABSTRACT: Previous studies show that most birds inhabiting temperate regions have well defined life history stages, and they modulate the production of testosterone (T) and corticosterone (CORT) in response to changes in seasonality. In this study we aimed to examine baseline and stress-induced levels of CORT and circulating T in relation with life history stages in the rufous-collared sparrow, Zonotrichia capensis. We carried out this study for a year in a population inhabiting riparian habitats in the Atacama Desert in Chile, one of the most climatically stable and driest places in the world. This environment shows minimal yearly change in average temperature and precipitation is virtually zero. We found individuals breeding, molting and overlapping breeding and molt year round, although most individuals were molting during March and in breeding condition during October. T levels were not related to individual breeding condition, and at population level they were not significantly different across sampling months. Baseline levels of CORT did not vary across the year. Stress-induced levels of CORT were suppressed during March when most of the birds were molting. This phenomenon was also observed in birds not molting during this period suggesting a mechanism other than molt in determining the stress-response suppression. Our results strongly suggest that in this study site, long-term extremely stable conditions could have relaxed the selective pressures over the timing of life history stages which was evidenced by the breeding and molt schedules, its overlap and endocrine profiles.
    General and Comparative Endocrinology 05/2013; · 2.82 Impact Factor
  • John C. Wingfield
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    ABSTRACT: Highlights ► Perturbations of the environment can be labile or permanent, with consequences for how animals respond. ► The exposome is the sum of environmental factors affecting an individual from conception to death. ► Allostasis and reactive scope concepts combine costs of daily routines and stress. ► The adrenocortical response to stress includes hormone secretion, transport and response. ► Stress responses involve modulation of robustness (resistance), responsiveness (flexibility) and resilience (recovery).
    Animal Behaviour. 05/2013; 85(5):1127–1133.
  • John C. Wingfield
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    ABSTRACT: 1. Rapid, effective and enduring responses of physiology and behaviour to perturbations of the environment are key to robustness of an organism (ability to resist perturbations) and resilience (ability to resist and recover quickly from perturbations) so that the normal life cycle can be resumed quickly. 2. Perturbations of the environment can be labile (i.e. eventually subside) or permanent such as when human activity changes the environment in the long term, for example, deforestation, urbanization, etc. 3. Hormonal responses to labile perturbation factors (LPFs) allow organisms to cope during the perturbation and then return to the normal life cycle. These hormonal responses are called stress responses especially in cases when major changes in physiology and behaviour occur (emergency life-history stage). 4. Permanent perturbations require more than just temporary acclimation resulting in changes in range, adaptation or in some cases local extinction. Perturbations can be abiotic, biotic and social, but these are not mutually exclusive. 5. Here I focus on the effects of abiotic perturbation factors and their effects on the hypothalamo-pituitary—adrenal/interrenal axis in vertebrates. There is a great need for more field investigations of responses of free-living populations to perturbations of the environment, especially now that it appears the frequency and intensity of these events is increasing. However, such studies will require a high degree of opportunism on the part of the investigators to take advantage of unpredictable events when they occur.
    Functional Ecology 02/2013; 27(1):37-44. · 4.86 Impact Factor
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    ABSTRACT: Glucocorticoids are essential for life and their secretion is regulated by the hypothalamic-pituitary-adrenal axis (HPA). The HPA axis is often divided into two components: baseline glucocorticoids levels and stress response glucocorticoids levels, which are affected by changes in ambient temperature and productivity among others factors. An approximation to evaluate how a species copes with these changes is to evaluate differences of this hormone amongst populations of the same species that inhabit places ideally presenting all the possible combinations of temperature and productivity. We aimed to evaluate whether environmental temperature or productivity, represent challenges in terms of stress in the Thorn-tailed Rayadito (Aphrastura spinicauda). We examined circulating baseline levels of CORT and stress responses from three populations, covering the whole geographic distribution of the species across large gradients in weather conditions. If low temperature influences baseline CORT levels, we expect higher levels of this hormone in the southernmost population (higher latitude). However, if productivity is the factor that influences baseline CORT levels, we expect the contrary pattern, that is, lower values of this hormone in the southernmost population (more productive environment). We observed that baseline CORT levels presented lower values in the southernmost population, supporting the environmental productivity hypothesis. Secondly, we tested the hypothesis that individuals breeding at higher latitudes should have a lower stress response than individuals breeding at lower latitudes. Contrary to our expectations, we found that stress response did not vary among populations in any of the three years. We concluded that low environmental temperatures did not represent a stress situation for the Thorn-tailed Rayadito if food abundance was sufficient to support energetic demands.
    General and Comparative Endocrinology 01/2013; · 2.82 Impact Factor
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    ABSTRACT: Abstract The roles of testosterone (T) during reproduction are often complex and vary among and within vertebrate taxa and locations, making general hypotheses relating T to breeding behavior and success difficult to integrate. In birds, T is thought to influence degrees of territoriality and associated aggression in males to maximize breeding success. Importantly, most work supporting these ideas has been conducted in the Northern Hemisphere. However, accumulating work on tropical species has shown divergent patterns of T in association with breeding behavior. The compilation of work from northern temperate and tropical species suggests that the function of T in relation to breeding behavior varies across latitude and environmental conditions. We investigate the patterns of T in relation to breeding behavior in a subspecies of the rufous-collared sparrow Zonotrichia capensis australis breeding at high latitude in the Southern Hemisphere (55°S). We then compare the T profiles and breeding behaviors of male Z. c. australis to conspecifics breeding in the tropics and congeners in North America to test the hypothesis that environments with breeding seasons of similar lengths will drive similar patterns of T in relation to breeding behavior. We found that Z. c. australis have high levels of T during the early-breeding periods when territories are being established and low levels of T during the parental phase of breeding, similar to temperate and Arctic birds in the Northern Hemisphere but unlike tropical Zonotrichia capensis costaricensis. In contrast, we found that Z. c. australis also exhibit similar aggressive behaviors in early breeding and midbreeding, unlike many birds in the Northern Hemisphere.
    Physiological and Biochemical Zoology 01/2013; 86(6):782-90. · 2.46 Impact Factor

Publication Stats

17k Citations
1,084.11 Total Impact Points

Institutions

  • 2001–2014
    • University of California, Davis
      • • Department of Neurobiology, Physiology and Behavior
      • • Department of Psychology
      Davis, California, United States
  • 2013
    • Gonzaga University
      Spokane, Washington, United States
    • Oklahoma State University - Oklahoma City
      Oklahoma City, Oklahoma, United States
  • 2009–2013
    • French National Centre for Scientific Research
      • Centre d'Ecologie Fonctionnelle et Evolutive
      Lutetia Parisorum, Île-de-France, France
    • Bucknell University
      • Department of Biology
      Lewisburg, PA, United States
    • The University of Western Ontario
      • Department of Biology
      London, Ontario, Canada
  • 1975–2013
    • University of Washington Seattle
      • • Department of Biology
      • • Department of Psychology
      Seattle, Washington, United States
  • 2012
    • University of California, Santa Barbara
      • Department of Ecology, Evolution, and Marine Biology
      Santa Barbara, CA, United States
  • 2006–2012
    • University of California, Berkeley
      • Department of Integrative Biology
      Berkeley, California, United States
    • The University of Edinburgh
      • Centre for Integrative Physiology
      Edinburgh, SCT, United Kingdom
    • New York State
      New York City, New York, United States
    • University of Oslo
      • Department of Biosciences
      Oslo, Oslo, Norway
    • Purdue University
      • Department of Biological Sciences
      West Lafayette, IN, United States
  • 2010
    • Universidad Nacional Autónoma de México
      • Department of Evolutionary Ecology
      Mexico City, The Federal District, Mexico
  • 2008–2010
    • Queen's University
      • Department of Biology
      Kingston, Ontario, Canada
    • The University of Memphis
      • Department of Biological Sciences
      Memphis, TN, United States
    • University of Antwerp
      • Departement Biologie
      Antwerpen, VLG, Belgium
  • 1987–2010
    • The Rockefeller University
      • • Laboratory of Neuroendocrinology
      • • Center for Field Research in Ethology and Ecology
      New York City, New York, United States
    • University of Gothenburg
      • Zoologiska institutionen
      Göteborg, Vaestra Goetaland, Sweden
  • 2007–2009
    • Waseda University
      • Department of Education (Faculty of Education and Integrated Arts and Sciences)
      Edo, Tōkyō, Japan
  • 2005–2008
    • College of Wooster
      • Department of Biology
      Wooster, OH, United States
    • University of Massachusetts Boston
      • Department of Biology
      Boston, MA, United States
  • 1998–2008
    • Tufts University
      • Department of Biology
      Medford, MA, United States
    • Arizona State University
      • School of Life Sciences
      Mesa, AZ, United States
  • 2004–2007
    • Max Planck Institute for Ornithology
      • Max Planck Institute for Ornithology (Radolfzell)
      Pöcking, Bavaria, Germany
  • 2005–2006
    • Hiroshima University
      • Faculty of Integrated Arts and Sciences
      Hiroshima-shi, Hiroshima-ken, Japan
    • University of Alaska Fairbanks
      • Department of Biology and Wildlife
      Fairbanks, AK, United States
  • 2004–2006
    • Virginia Polytechnic Institute and State University
      • Department of Biological Sciences
      Blacksburg, VA, United States
  • 2003–2006
    • University of Texas at Austin
      • Department of Integrative Biology
      Austin, TX, United States
    • University of California, San Francisco
      San Francisco, California, United States
    • University of California, Santa Cruz
      • Department of Ecology & Evolutionary Biology
      Santa Cruz, CA, United States
    • Lund University
      • Department of Animal Ecology
      Lund, Skane, Sweden
    • Northern Arizona University
      • Department of Biological Sciences
      Flagstaff, AZ, United States
  • 2002
    • Koninklijk Nederlands Instituut voor Onderzoek der Zee - NIOZ
      Burg, North Holland, Netherlands
  • 1982–2002
    • CSU Mentor
      Long Beach, California, United States
  • 2000
    • University of Illinois, Urbana-Champaign
      Urbana, Illinois, United States
    • Swarthmore College
      • Department of Biology
      Swarthmore, PA, United States
  • 1994–2000
    • University of Wollongong
      • School of Biological Sciences
      Wollongong, New South Wales, Australia
  • 1999
    • Occidental College
      • Department of Biology
      Los Angeles, CA, United States
    • The Roslin Institute
      Edinburgh, Scotland, United Kingdom
  • 1989–1997
    • Tokyo Medical and Dental University
      Edo, Tōkyō, Japan
  • 1996
    • Indiana University Bloomington
      • Department of Biology
      Bloomington, IN, United States
  • 1980–1984
    • Eastern Washington University
      Cheney, Washington, United States
  • 1981
    • University of Bristol
      Bristol, England, United Kingdom