IBIS | Volume 157 | Issue 3 | July 2015
The latest issue of IBIS is one of our most packed yet, featuring 16 full papers and 5 short communications, plus our usual extensive book review section.
Here are just four of the many highlights in this issue.
Ontogenic differences in sexual size dimorphism across four plover populations
Natalie Dos Remedios, TamÃ¡s SzÃ©kely, Clemens KÃ¼pper,
Patricia L. M. Lee & AndrÃ¡s KosztolÃ¡nyi
In many species, the sexes differ in size. But when do these differences emerge? Natalie Dos Remedios of the University of Bath and colleagues look at the emergence of sexual size difference in the chicks of two closely related shorebirds, Kentish Plover and Snowy Plover. Remarkably, they find that patterns differ between populations; in some populations, male and female chicks already differ in size at birth. In others, chicks hatch the same size but males grow faster than females. In one population, there was no difference in size between the sexes. Thus, it appears that sexual size dimorphism can emerge in different ways in different populations of the same species.
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Off-nest behaviour in a biparentally incubating shorebird varies with sex, time of day and weather
Martin Bulla, Elias Stich, Mihai Valcu & Bart Kempenaers
Staying with shorebirds, Martin Bulla and colleagues at the Max Planck Institute for Ornithology, Behavioural Ecology and Evolutionary Genetics examine the conflict between parents that share incubation. Sharing incubation represents a collaboration but also a potential source of conflict, since incubation needs to be set against other priorities, such as feeding. Studying radio-tagged Semipalmated Sandpipers in Alaska, Bulla and colleagues studied the behaviour of the parent that was not incubating. They find that the non-incubating bird tends to move considerable distances from the nest and so the parents do not continually keep track of each other, rather it is the off-duty parentâ€™s decision to return to the nest that drives the length of incubation bouts.
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Bird movements at rotor heights measured continuously with vertical radar at a Dutch offshore wind farm
Ruben C. Fijn, Karen L. Krijgsveld, Martin J. M. Poot & Sjoerd Dirksen
One of the greatest changes to have taken place to European landscapes in recent decades has been the proliferation of wind turbines. These are known to pose a risk to birds but quantifying this has proved problematic. Using vertical radar with automated bird-tracking software, Ruben Fijn of the Bureau Waardenburgâ€™s Department of Bird Ecology and colleagues estimate that 1.6 million birds pass through a large offshore Dutch wind farm at heights that make them vulnerable to being hit by rotors. These are mostly gulls during the day and migrating passerines at night. Numbers passing at risk heights varied across time and with wind direction. The results further our understanding of the likely impacts of offshore wind farms.
Causes of the latitudinal gradient in birdsong complexity assessed from geographical variation within two Himalayan warbler species
Pratap Singh & Trevor D. Price
The song of a particular species can vary geographically, typically increasing in complexity with increasing latitude. Working on two species of warbler in the Himalayas, Pratap Singh of the Wildlife Institute of India and Trevor Price of the University of Chicago investigate these patterns further, showing that song complexity in both species increases from south-east to north-west, though in different measures of complexity. They suggest that this is the result of a lower overall bird density and hence lower volume of background bird song in the north-west, allowing complexity to be better heard in these quieter environments. Such a pattern may explain inter- as well as intra-specific variation in the complexity of song.