Search

Sylvicultural practices are increasingly directed at forest conservation, restoration and sustainable management. Forests with higher structural complexity are expected to be more resilient against climate change impacts and to have a higher diversity of ecological niches. The impact of forest structural complexity on individual organisms, however, is less well known. To bridge this knowledge gap, we here test if structurally more complex forests provide a more favourable nutritional environment for forests birds, using ptilochronology as an indicator for individual condition. We therefore measured the width of growth bars in tail feathers of great tits (Parus major) captured in 19 forest plots along a gradient of increasing structural complexity. After validating our assumption that series of growth bars reflect the outcome of an energetic income vs. expenditure balance with possible consequences for health and fitness, we show that birds in structurally more complex forests maintain a better nutritional status, probably due to a higher and more stable availability of food resources and more sheltered habitat. Dominant tree species, architecture and associated ecology also play an important role, as some of the observed relationships appear to be tree species-specific. Overall, we demonstrate the importance of a complex forest structure and herb layer, and argue for the need for individual research on the condition, performance and health of forest species to inform managers and policymakers on the impact of changing forestry practices on biodiversity and ecosystem functioning.

Forest fragmentation, a result of deforestation, not only decreases the amount of habitat available for wildlife, but also increases the isolation of the remaining fragments and the area of edges surrounding them. Also, deforestation often leads to the creation of a dynamic regenerating matrix where cleared land is subsequently abandoned. Here we examine the effects of fragmentation and landscape change on the nutritional condition of Amazonian rainforest birds at the Biological Dynamics of Forest Fragments Project, near Manaus, Brazil. We analyzed ptilochronology-based measurements of feather growth rate in 12 species living in fragments within a dynamic landscape over 21 years. Ptilochronology serves as an index of nutritional condition by revealing energy available for maintenance over 1–2 weeks while the feather is grown, allowing intraspecific comparison across treatments. Feather growth rate decreased in fragments surrounded by young second-growth borders but increased as fragment size and age of adjacent second-growth vegetation increased. Results from this simple, yet informative, measure of nutritional condition reveal physiological impacts of land cover change, including the response of birds to changes occurring at both local and landscape levels. Our results highlight the importance of looking beyond presence/absence data to describe fragmentation effects, and support the value of landscape-scale approaches for the conservation of tropical forest biodiversity.

A non-invasive study of trace element accumulation in tail feathers of the Kentish plover (Charadrius alexandrinus) was performed along the coastline of the northern littoral strip of the Venice Lagoon, with the aim to verify whether contamination may be a factor affecting conservation status of Kentish plover populations. Body burdens in feathers of 11 trace elements including toxic metals/metalloids and essential elements (As, Cd, Co, Cr, Cu, Hg, Ni, Pb, Se, V, Zn) were quantified by ICP-MS, then concentrations were normalized to feather's age calculated using ptilochronology in order to obtain daily deposition rates. Mercury emerged as a major threat to the conservation of the species, since average feather concentration was clearly above the adverse-effect threshold associated with impairment in the reproductive success in a number of bird species. Also Cd and Se occurred at levels that may impact on the conservation status of the studied species at local scale, even if to a lesser extent than Hg. Gender-related differences in trace element accumulation emerged only for As, although for this element the risks associated to environmental exposure seem to be negligible., (Copyright © 2019 Elsevier Inc. All rights reserved.)