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Links between fear of humans, stress and survival support a non-random distribution of birds among urban and rural habitats.

Rebolo-Ifrán N, Carrete M, Sanz-Aguilar A, Rodríguez-Martínez S, Cabezas S, Marchant TA, Bortolotti GR, Tella JL - Sci Rep (2015)

Bottom Line: Recent research efforts have yielded controversial results based on short-term measures of stress, without exploring its fitness effects.FIDs were shorter in urban than in rural birds, but CORTf levels did not differ, nor were correlated to FIDs.These results evidence that urban life does not constitute an additional source of stress for urban individuals, as shown by their near identical CORTf values compared with rural conspecifics supporting the non-random distribution of individuals among habitats according to their behavioural phenotypes.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Ecología, Genética y Evolución &IEGEBA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.

ABSTRACT
Urban endocrine ecology aims to understand how organisms cope with new sources of stress and maintain allostatic load to thrive in an increasingly urbanized world. Recent research efforts have yielded controversial results based on short-term measures of stress, without exploring its fitness effects. We measured feather corticosterone (CORTf, reflecting the duration and amplitude of glucocorticoid secretion over several weeks) and subsequent annual survival in urban and rural burrowing owls. This species shows high individual consistency in fear of humans (i.e., flight initiation distance, FID), allowing us to hypothesize that individuals distribute among habitats according to their tolerance to human disturbance. FIDs were shorter in urban than in rural birds, but CORTf levels did not differ, nor were correlated to FIDs. Survival was twice as high in urban as in rural birds and links with CORTf varied between habitats: while a quadratic relationship supports stabilizing selection in urban birds, high predation rates may have masked CORTf-survival relationship in rural ones. These results evidence that urban life does not constitute an additional source of stress for urban individuals, as shown by their near identical CORTf values compared with rural conspecifics supporting the non-random distribution of individuals among habitats according to their behavioural phenotypes.

No MeSH data available.


Estimates of annual survival (mean and 95% CI) obtained for 109 urban and 74 rural adult burrowing owls.
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f2: Estimates of annual survival (mean and 95% CI) obtained for 109 urban and 74 rural adult burrowing owls.

Mentions: The goodness-of-fit of the general model fitted the data adequately (χ2 = 2, df = 5, p = 0.85). We started model selection by testing the effects of time and habitat type on resighting (p) and survival (ϕ) probabilities (Table 2). The best model (Model 1, Table 2) included a temporal effect on resighting probability, which was relatively high (pmean = 0.81, 95% CI = 0.68–0.89) and did not vary between habitats. However, survival differed between habitats, being more than twice as high in urban (ϕ = 0.59) as in rural (ϕ = 0.25) individuals (Fig. 2). Models including additional temporal effects on survival had ΔAICc > 2 and much lower Akaike weights (Table 2). Consequently, we selected the structure of this model to test for CORTf effects on subsequent annual survival.


Links between fear of humans, stress and survival support a non-random distribution of birds among urban and rural habitats.

Rebolo-Ifrán N, Carrete M, Sanz-Aguilar A, Rodríguez-Martínez S, Cabezas S, Marchant TA, Bortolotti GR, Tella JL - Sci Rep (2015)

Estimates of annual survival (mean and 95% CI) obtained for 109 urban and 74 rural adult burrowing owls.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4562227&req=5

f2: Estimates of annual survival (mean and 95% CI) obtained for 109 urban and 74 rural adult burrowing owls.
Mentions: The goodness-of-fit of the general model fitted the data adequately (χ2 = 2, df = 5, p = 0.85). We started model selection by testing the effects of time and habitat type on resighting (p) and survival (ϕ) probabilities (Table 2). The best model (Model 1, Table 2) included a temporal effect on resighting probability, which was relatively high (pmean = 0.81, 95% CI = 0.68–0.89) and did not vary between habitats. However, survival differed between habitats, being more than twice as high in urban (ϕ = 0.59) as in rural (ϕ = 0.25) individuals (Fig. 2). Models including additional temporal effects on survival had ΔAICc > 2 and much lower Akaike weights (Table 2). Consequently, we selected the structure of this model to test for CORTf effects on subsequent annual survival.

Bottom Line: Recent research efforts have yielded controversial results based on short-term measures of stress, without exploring its fitness effects.FIDs were shorter in urban than in rural birds, but CORTf levels did not differ, nor were correlated to FIDs.These results evidence that urban life does not constitute an additional source of stress for urban individuals, as shown by their near identical CORTf values compared with rural conspecifics supporting the non-random distribution of individuals among habitats according to their behavioural phenotypes.

View Article: PubMed Central - PubMed

Affiliation: Departamento de Ecología, Genética y Evolución &IEGEBA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Buenos Aires, Argentina.

ABSTRACT
Urban endocrine ecology aims to understand how organisms cope with new sources of stress and maintain allostatic load to thrive in an increasingly urbanized world. Recent research efforts have yielded controversial results based on short-term measures of stress, without exploring its fitness effects. We measured feather corticosterone (CORTf, reflecting the duration and amplitude of glucocorticoid secretion over several weeks) and subsequent annual survival in urban and rural burrowing owls. This species shows high individual consistency in fear of humans (i.e., flight initiation distance, FID), allowing us to hypothesize that individuals distribute among habitats according to their tolerance to human disturbance. FIDs were shorter in urban than in rural birds, but CORTf levels did not differ, nor were correlated to FIDs. Survival was twice as high in urban as in rural birds and links with CORTf varied between habitats: while a quadratic relationship supports stabilizing selection in urban birds, high predation rates may have masked CORTf-survival relationship in rural ones. These results evidence that urban life does not constitute an additional source of stress for urban individuals, as shown by their near identical CORTf values compared with rural conspecifics supporting the non-random distribution of individuals among habitats according to their behavioural phenotypes.

No MeSH data available.