Shortening day length as a previously unrecognized selective pressure for early breeding in a bird with long parental care

Several different selective pressures have been suggested to explain an intense competition for early return to breeding grounds in birds. In this study we hypothesized that shortening day length during summer months may constitute additional selective force acting towards early breeding in avian species with long parental care. To test this hypothesis, we studied time budget and foraging activities of early-nesting and late-nesting white storks Ciconia ciconia from the Central-European population. We found that duration and distance of foraging trips increased significantly over the course of the reproductive season. The relative frequency of foraging trips increased at the expense of other activities, such as resting, plumage maintenance, and nest maintenance. Mean daily foraging duration increased with increasing day length in the early part of the season, with 0.68 h of foraging per individual per 13.16 h of day length in mid-April increasing to 7.42 h of foraging per individual during solstice (16.61 h of day length). Afterwards, mean foraging duration continued increasing in spite of decreasing day length, reaching 11.63 h of foraging per individual per 14.92 h of day length at the end of the season in mid-August, when storks were forced to continue foraging after sunset in order to meet energy requirements of fledglings. The results suggest that shortening day length during summer months may constitute a serious time constraint on food delivery rates to offspring for late-breeding pairs of white storkEuropean Social Fund and the Polish National Budget in the D-RIM project of the Human Capital Programm

Environmental evaluation of Łódź basing on breeding avifauna composition

The evaluation was conducted using the bird species richness and occurrence of the key species. The key species were: 1. Species endangered globally according to IU CN/BirdLife International criteria, 2. Species of European Conservation Concern (C ategory 1-3), 3. Species from Annex I of Council Directive on the Convention of Wild Birds (79/409/EEC) 4. Species from Polish Red Animal Book, 5. Species which frequency of occurrence in Poland is < 10% according to Atlas of Breeding Birds in Poland data, 6 . Species which number of Polish breeding population is less than 1000 pairs. The key species breed in all kinds of habitats in Łódź. The most valuable habitats are weakly urbanized areas of river valleys and forest habitats with old tree-stands. Among the habitats the most endangered by changes are: river valleys and farmland areas.Zadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 dofinansowane zostało ze środków MNiSW w ramach działalności upowszechniającej naukę

Additional file 1: of Plumage quality mediates a life-history trade-off in a migratory bird

Raw data for feather measurements, moult status, and migratory traits of the first-year common snipe. (XLSX 28 kb