Bitter fruits of hard labour: diet metabarcoding and telemetry reveal that urban songbirds travel further for lower-quality food

Jarrett, Crinan; Powell, Luke L.; McDevitt, Heather; Helm, Barbara; Welch, Andreanna J.

doi:10.1007/s00442-020-04678-w

Cited by 35 publications

(53 citation statements)

References 72 publications

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“…When compared to more natural areas, urban environments often harbour a reduced abundance of arthropods (Jones & Leather 2012, New 2015, Fenoglio et al 2020, which may also be of lower quality (e.g., lower carotenoid content in caterpillars at urban versus rural sites; Isaksson & Andersson 2007) and have smaller body size (Merckx et al 2018), resulting in a relative scarcity of high-quality food sources (e.g., lepidopteran larvae; Narango et al 2018, Seress et al 2018, 2020, Jarrett et al 2020 for urban insectivorous birds. On the other hand, cities offer large amounts of low-quality, easily accessible anthropogenic food which is readily consumed by birds (Robb et al 2008).…”

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confidence: 99%

Urban nestlings have reduced number of feathers in Great Tits (Parus major)

Sándor

Liker

Sinkovics

et al. 2021

Ibis

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The plumage of birds plays an essential role in thermal insulation and influences the heat tolerance of birds. These plumage functions are mainly determined by the number and the density of feathers, but it is unclear how feather density responds to environmental changes in wild populations. In urban birds, both high temperature and limited food could generate changes in plumage traits. To investigate the effect of urbanization, we compared the number of feathers in nestlings between urban and forest Great Tits Parus major using a novel non-invasive method. We showed that urban nestlings have fewer feathers than forest nestlings at 6-9 days old. Although the density of feathers was slightly higher in urban nestlings, this was the result of the smaller size of their feather tracts. We suggest that the reduced feather number may be the result of either adaptation to higher urban temperatures, constrained feather development due to limited optimal nestling-food sources in urban environments, or both. Concentrating body feathers in a reduced tract area may also help birds to adapt to higher urban temperatures because this can increase the relative size of bare body surfaces which may facilitate heat dissipation. We suggest several possibilities for future studies that would help to disentangle the underlying mechanisms responsible for the observed patterns.

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confidence: 99%

Urban nestlings have reduced number of feathers in Great Tits (Parus major)

Sándor

Liker

Sinkovics

et al. 2021

Ibis

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“…Four non-mutually exclusive scenarios are possible. First, spatial heterogeneity (habitat fragmentation), lower food availability or human disturbance in the urban environment may decrease coordinated behaviours because parents may need to forage in different locations 24 or further away from the nest 57 . Empirical evidence in zebra finches Taeniopygia guttata showed that parents foraging independently from each other at different foraging areas decreased synchrony of nest visits 16 .…”

Section: Discussionmentioning

confidence: 99%

“…Urban areas, such as our suburban site, may thus induce parents to forage independently from each other more often, resulting in lower coordination of their nest visits. A recent radio-tracking study on blue tits Cyanistes caeruleus showed differences in foraging behaviour between populations at an urban and rural site in that provisioning trips occur on average further from the nest for parents nesting in an urban site compared to a forest site 57 . However, to the best of our knowledge, it is not known whether urban environments also affect other aspect of the foraging behaviour, such as the number of foraging locations or the coordination between the parents (whether parents forage together or independently from each other).Further telemetry studies with both parents tracked simultaneously are necessary to shed lights on space use and pair coordination of foraging parents in urban areas.…”

Section: Discussionmentioning

confidence: 99%

Urban resources limit pair coordination over offspring provisioning

Baldan

Ouyang

2020

Sci Rep

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The amount of care parents provide to the offspring is complicated by an evolutionary conflict of interest (‘sexual conflict’) between the two parents. Recent theoretical models suggest that pair coordination of the provisioning may reduce this conflict and increase parent and offspring fitness. Despite empirical studies showing that pair coordination is common in avian species, it remains unclear how environmental and ecological conditions might promote or limit the ability of parents to coordinate care. We compared the level of pair coordination, measured as alternation and synchrony of the nest visits, of house wrens Troglodytes aedon pairs breeding in a rural (10 nests) and a suburban (9 nests) site and investigated how differences in parental behaviours were related to habitat composition, prey abundance and how they ultimately related to reproductive success. We found that parents alternated and synchronized their nest visits more in the rural site compared to the suburban one. The suburban site is characterized by a more fragmented habitat with more coniferous trees and less caterpillar availability. Offspring from the rural site were heavier at fledging than at the suburban site. Taken together, these results suggest that environmental conditions play an important role on the emergence of coordinated parental care and that considering environmental variables is pivotal to assess the fitness consequences of parental strategies.

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“…Blue tit chicks typically fledge at 18 days of age and, in our populations, lay an average of nine eggs. Both clutch size and fledging success are usually higher in the forest than in the city sites ( Pollock et al 2017 ; Jarrett et al 2020 ). Nestbox temperature does not differ between our urban and forest sites (Dominoni et al, in review).…”

Section: Methodsmentioning

confidence: 99%

Feather, But Not Plasma, Glucocorticoid Response to Artificial Light at Night Differs between Urban and Forest Blue Tit Nestlings

Dominoni

Teo

Branston

et al. 2021

Integrative and Comparative Biology

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Urbanization drives phenotypic variation in many animal species. This includes behavioral and physiological traits such as activity patterns, aggression, and hormone levels. A current challenge of urban evolutionary ecology is to understand the environmental drivers of phenotypic variation in cities. Moreover, do individuals develop tolerance to urban environmental factors, which underlie adaptative responses and contribute to the evolution of urban populations? Most available evidence comes from correlative studies and rare experiments where a single urban-related environmental factor has been manipulated in the field. Here we present the results of an experiment in which we tested for differences in the glucocorticoid (CORT) response of urban and rural blue tits nestlings (Cyanistes caeruleus) to artificial light at night (ALAN). ALAN has been suggested to alter CORT response in several animal species, but to date no study has investigated whether this effect of ALAN differs between urban and rural populations. Immediately after hatching, urban and forest broods were either exposed to 2 lux of ALAN (using an LED source mounted inside the nestbox) or received no treatment (dark control). The experiment lasted until the chicks fledged. When the chicks were 13 days old plasma samples were collected to measure baseline CORT concentrations, and feather samples to provide an integrative measure of CORT during growth. Forest birds had higher plasma CORT (pCORT) concentrations than their urban counterparts, irrespective of whether they were exposed to ALAN or not. Conversely, we found population-specific responses of feather CORT to ALAN. Specifically, urban birds that received ALAN had increased feather CORT compared with the urban dark controls, while the opposite was true for the forest birds. pCORT concentrations were negatively associated to fledging success, irrespective of population and treatment, while feather CORT was positively associated to fledging success in broods exposed to ALAN, but negatively in the dark control ones. Our results demonstrate that ALAN can play a role in determination of the glucocorticoid phenotype of wild animals, and may thus contribute to phenotypic differences between urban and rural animals.

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Bitter fruits of hard labour: diet metabarcoding and telemetry reveal that urban songbirds travel further for lower-quality food

Cited by 35 publications

References 72 publications

Urban nestlings have reduced number of feathers in Great Tits (Parus major)

Urban nestlings have reduced number of feathers in Great Tits (Parus major)

Urban resources limit pair coordination over offspring provisioning

Feather, But Not Plasma, Glucocorticoid Response to Artificial Light at Night Differs between Urban and Forest Blue Tit Nestlings

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