Across time and space: Effects of urbanization on corticosterone and body condition vary over multiple years in song sparrows (<i>Melospiza melodia</i>)

Foltz, Sarah L.; Davis, Jason; Battle, Kathryn E.; Greene, Virginia; Laing, Brenton T.; Rock, Ryan P.; Ross, Allen E.; Tallant, James A.; Vega, Rene; Moore, Ignacio T.

doi:10.1002/jez.1906

Cited by 30 publications

(17 citation statements)

References 69 publications

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“…In order to investigate the generality of differences we saw between these sites, in May and June 2015 we performed a subsequent set of trials involving heterospecific alarm call playbacks with male song sparrows at multiple urban and rural locations in western North Carolina. We chose to focus only on response to heterospecific alarm calls because FID and territorial aggression have been measured in multiple populations (Evans et al 2010, Scales et al 2011, Foltz et al 2015a, with aggression and FID reported to be higher in urban habitats than in rural ones. Thus, it was more valuable to establish that the behavioral measure unique to this study, namely, response to heterospecific alarm calls, differed between a large number of urban versus rural sites.…”

Section: Methodsmentioning

confidence: 99%

Differences in measures of boldness even when underlying behavioral syndromes are present in two populations of the song sparrow (Melospiza melodia)

Myers

Hyman

2016

J Ethol

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One commonly studied behavioral syndrome is the correlation between aggression and boldness. Studies in song sparrows (M. melodia) have found greater aggression and boldness in urban populations and a correlation between aggression and boldness in rural populations, but not within urban populations. In previous studies, boldness was measured as flight initiation distance (FID), which may reflect habituation by urban birds to human presence. In this study, we measured boldness using playbacks of heterospecific alarm calls and investigated whether higher boldness is a general trait of urban birds and whether the same pattern of correlations between aggression and boldness would be seen. We conducted trials involving FID, alarm call playbacks and conspecific song playbacks on 25 birds from both an urban and a rural site. The results showed that urban birds were bolder, as measured by FID and response to alarm calls. Boldness and aggression were correlated in rural birds with each method of measuring boldness but were correlated in urban birds only when using alarm call playbacks. Our results suggest that a behavioral syndrome exists in both urban and rural populations but that urban birds are able to decrease their response to human disturbance.

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Section: Methodsmentioning

confidence: 99%

Differences in measures of boldness even when underlying behavioral syndromes are present in two populations of the song sparrow (Melospiza melodia)

Myers

Hyman

2016

J Ethol

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“…It is unclear why the CORT response to stress differed between urban and desert males. Studies of a range of species and urban areas have shown that the effect of urbanization on the CORT stress response is variable both within and between studies (Bókony et al 2012;Bonier et al 2007;Davies et al 2013;Fokidis et al 2009;Foltz et al 2015;Partecke et al 2006;Schoech et al 2007). The factors underlying this variation remain a central question in urban physiological ecology.…”

Section: Associations Between Initial and Stress-induced Changes In Pmentioning

confidence: 96%

“…If plasma T is correlated with the innate immune response to stress, we would expect differences in this response between the sexes. At the population level, compared to their non-urban counterparts, individuals inhabiting urban areas sometimes, although not always, adjust aspects of their physiology, including plasma CORT (Bókony et al 2012;Bonier et al 2007;Davies et al 2013;Fokidis et al 2009;Foltz et al 2015;Partecke et al 2006;Schoech et al 2007) and T (Atwell et al 2014;Fokidis et al 2011b;Partecke et al 2005), as well as immunological parameters (Bókony et al 2012;Fokidis et al 2008;Powell et al 2013;Ruiz et al 2002). In the present study we used this natural sex and population level variation to shed light on the relationships between plasma CORT, plasma T, and immunity during acute stress.…”

Section: Introductionmentioning

confidence: 95%

Innate immunity and testosterone rapidly respond to acute stress, but is corticosterone at the helm?

et al. 2016

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When faced with a stressor, vertebrates can rapidly increase the secretion of glucocorticoids, which is thought to improve the chances of survival. Concurrent changes in other physiological systems, such as the reproductive endocrine or innate immune systems, have received less attention, particularly in wild vertebrates. It is often thought that glucocorticoids directly modulate immune performance during a stress response, but, in many species, androgens also rapidly respond to stress. However, to our knowledge, no study has simultaneously examined the interactions between the glucocorticoid, androgen, and innate immune responses to stress in a wild vertebrate. To address this issue, we tested the hypothesis that the change in plasma corticosterone (CORT) in response to the acute stress of capture and restraint is correlated with the concurrent changes in plasma testosterone (T) and innate immune performance (estimated by the capacity of plasma to agglutinate and lyse foreign cells) in the Abert's Towhee (Melozone aberti). Furthermore, to broaden the generality of the findings, we compared male and female towhees, as well as males from urban and non-urban populations. Acute stress increased plasma CORT, decreased plasma T in males, and decreased innate immune performance, but the increase in CORT during stress was not correlated with the corresponding decreases in either plasma T or innate immunity. By contrast, the plasma T stress response was positively correlated with the innate immune stress response. Collectively, our results challenge the proposition that the glucocorticoid stress response is correlated with the concurrent changes in plasma T, a key reproductive hormone, and innate immunity, as estimated by agglutination and lysis.

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“…However, regardless of the fitness benefit of the behavior, proximate mechanisms must mediate behavioral differences. Despite repeated demonstrations of behavioral differences in song sparrows living along urban-rural gradients, the neural and physiological basis of differences in aggression are not fully understood (Evans et al, 2010;Foltz et al, 2015a;Davies and Sewall, 2016).…”

Section: Introductionmentioning

confidence: 99%

“…A first step in this process is to compare measures of the physiological processes that underlie behavior in animals living in different habitats to determine which traits vary and therefore could regulate behavioral changes. Prior studies have failed to find reliable differences in levels of the avian stress hormone, corticosterone, between rural and urban songbirds despite predictions that urban habitats could impact stress reactivity (Partecke et al, 2006;Bonier et al, 2007;Schoech et al, 2007;Fokidis et al, 2009Fokidis et al, , 2011Atwell et al, 2012;Bonier, 2012;Foltz et al, 2015a). Nor have consistent differences been reported in levels of testosterone, a hormone traditionally thought to promote aggression in vertebrates (Partecke et al, 2005;Fokidis et al, 2011;Deviche and Davies, 2013;Atwell et al, 2014;Davies and Sewall, 2016;.…”

Section: Introductionmentioning

confidence: 99%

Two Neural Measures Differ between Urban and Rural Song Sparrows after Conspecific Song Playback

Sewall

Davies

2017

Front. Ecol. Evol.

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Urbanization is a critical form of environmental change that can affect the physiology and behavior of wild animals and, notably, birds. One behavioral difference between birds living in urban and rural habitats is that urban males show elevated boldness or territorial aggression in response to simulated social challenge. This pattern has been described in several populations of song sparrow, Melospiza melodia. Such behavioral differences must be underpinned by differences in the brain, yet little work has explored how urbanization and neural function may be interrelated. We explored the relationship between urbanization and neural activation within a network of brain regions, collectively called the social behavior network, which contributes to the regulation of territorial aggression. Specifically, we captured free-living, territorial male song sparrows by playing them conspecific songs for 6-11 min, and then collected their brains. We estimated recent neural activation, as indicated by the immediate early gene FOS, and measured levels of a neuropeptide, arginine vasotocin (AVT), which is involved in the regulation of social behavior. Based on previous studies we expected urban males, which are generally more territorially aggressive, to have lower FOS expression in a node of the social behavior network implicated in regulating territoriality, the lateral septum (LS). Additionally, we expected urban males to have lower AVT expression in a brain region involved in the regulation of sociality, the medial bed nucleus of the stria terminalis (BSTm). We found that, compared to rural males, urban male song sparrows did have lower FOS expression in the LS. This pattern suggests that lower neural activation in the LS could contribute to behavioral adjustments to urbanization in male song sparrows. Additionally, counter to our predictions, urban male song sparrows had higher AVT-like immunoreactivity in the BSTm. Future work building upon these findings is needed to determine the causal role of such neural differences across rural and urban habitats. Understanding the mechanisms impacted by urbanization will inform our understanding of the reversibility and consequences of this form of habitat change.

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Across time and space: Effects of urbanization on corticosterone and body condition vary over multiple years in song sparrows (Melospiza melodia)

Cited by 30 publications

References 69 publications

Differences in measures of boldness even when underlying behavioral syndromes are present in two populations of the song sparrow (Melospiza melodia)

Differences in measures of boldness even when underlying behavioral syndromes are present in two populations of the song sparrow (Melospiza melodia)

Innate immunity and testosterone rapidly respond to acute stress, but is corticosterone at the helm?

Two Neural Measures Differ between Urban and Rural Song Sparrows after Conspecific Song Playback

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