Higher frequency of extra-pair offspring in urban than forest broods of great tits ( Parus major )

Vincze

et al. 2021

Sci Rep

Self Cite

The ubiquitous activity of humans is a fundamental feature of urban environments affecting local wildlife in several ways. Testing the influence of human disturbance would ideally need experimental approach, however, in cities, this is challenging at relevant spatial and temporal scales. Thus, to better understand the ecological effects of human activity, we exploited the opportunity that the city-wide lockdowns due to the COVID-19 pandemic provided during the spring of 2020. We assessed changes in reproductive success of great tits (Parus major) at two urban habitats affected strikingly differently by the ‘anthropause’, and at an unaffected forest site. Our results do not support that urban great tits benefited from reduced human mobility during the lockdown. First, at one of our urban sites, the strongly (− 44%) reduced human disturbance in 2020 (compared to a long-term reference period) did not increase birds’ reproductive output relative to the forest habitat where human disturbance was low in all years. Second, in the other urban habitat, recreational human activity considerably increased (+ 40%) during the lockdown and this was associated with strongly reduced nestling body size compared to the pre-COVID reference year. Analyses of other environmental factors (meteorological conditions, lockdown-induced changes in air pollution) suggest that these are not likely to explain our results. Our study supports that intensified human disturbance can have adverse fitness consequences in urban populations. It also highlights that a few months of ‘anthropause’ is not enough to counterweight the detrimental impacts of urbanization on local wildlife populations.

Section: Methodsmentioning

confidence: 99%

Contrasting effects of the COVID-19 lockdown on urban birds’ reproductive success in two cities

Seress

Vincze

et al. 2021

Sci Rep

Self Cite

“…Next, to test our predictions for the effects of habitat type on feather tract traits, we followed the approach suggested by Ruxton and Beauchamp (2008) and conducted pre-planned comparisons between the study sites in two steps (see also e.g. Pipoly et al 2019;Seress et al 2020). In the first step, we identified significant confounding variables besides the effect of the main predictor (study site).…”

Section: Statistical Analysesmentioning

confidence: 99%

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

Liker

Sinkovics

et al. 2021

Ibis

Self Cite

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.

“…In the second step, we used these linear models for each response variable to conduct the pre-planned comparisons by calculating linear contrasts from each model's marginal means (package 'emmeans') between the two forest and two urban sites (for similar approach see also Pipoly et al 2019) separately for FY and AFY birds. We compared habitats separately for the two age groups because they likely differed in their moulting conditions.…”

Section: Discussionmentioning

confidence: 99%

Differences in feather structure between urban and forest great tits: constraint or adaptation?

Journal of Avian Biology

Seress

Sinkovics

et al. 2022

Self Cite

Urbanization is one of the strongest habitat transforming processes today that has resulted in changes in the ecological conditions for wild populations. In birds, the limitation of natural food sources and a warmer microclimate in cities can potentially influence the development and functioning of the plumage that may have important fitness consequences. Despite its potential significance, the plumage structure of urban birds are largely unexplored and it is unclear whether and how they respond to urban ecological processes such as different constraints and selection pressures. In this study, we compared several structural properties of contour, primary and tail feathers between two forest and two urban great tit Parus major populations. Our results show that the urban environment affects only a few structural properties of feathers and only in the plumage of first‐year birds. We found that both the plumulaceous and the pennaceous parts of their contour feathers are longer and have lower barb density in the urban than in the forest habitat. We also found that the primaries of first‐year birds have narrower rachis and higher barbule density in the cities than in the forests, but there were no differences in other wing feather traits and in any tail feather traits between habitats. We did not find differences in the feather structure of urban versus forest adult birds. The habitat differences in first‐year birds may indicate nutritional constraints or the effects of the warmer microclimate of the urban environment. These differences seem to disappear completely in adulthood that can be explained by the selective mortality of first‐year birds, or by adults being less sensitive than first‐year birds to environmental effects during their moult.