Wild Birds Unlimited: Female Birds Aren’t So Dull After All

http://lansingwbu.blogspot.com/2014/06/female-birds-arent-so-dull-after-all.html?m=1

How to get there: golden eagle flight behaviour during migration

Functional Ecology: Plain Language Summaries

Enrico Pirotta, Todd Katzner, Tricia A. Miller, Adam E. Duerr, Melissa A. Brahame and Leslie New

Modern technologies allow us to follow wide-ranging animals over large distances and long periods of time, opening a window on unknown aspects of their behaviour and ecology. For example, the data collected by GPS tracking devices can be used to understand not only where animals go, but also how they choose to move in their environment.

A golden eagle, Aquila chrysaetos (Photo credit: David Brandes, Lafayette College, Easton, PA). A golden eagle, Aquila chrysaetos (Photo credit: David Brandes, Lafayette College, Easton, PA).

Birds adopt different strategies to move through air, depending on their size, body structure, the reason for moving, and the environmental and weather conditions they encounter. Because flapping flight is energetically expensive, heavier birds tend to use air currents to support straight-winged flight, an efficient way of moving known as soaring. The air currents can either result from layers of warm air that rise from…

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Why are some birds ‘larks’ and others ‘owls’?

Functional Ecology: Plain Language Summaries

Julia Karagicheva, Eldar Rakhimberdiev, Anatoly Saveliev & Theunis Piersma

Time is relative. For some organisms one year is a lifetime, for others it is just a tiny chunk of it. When life is short, one has to take every chance, as there will not be too many left. But with many years ahead, animals can afford to skip an opportunity.

Red knots (Calidris canutus) in flight. Photo credit: Jan van de Kam Red knots (Calidris canutus) in flight. Photo credit: Jan van de Kam

In animals that cannot afford to forego a breeding opportunity because life is short, it is also better to breed as early in the season as possible – even if this come with costs. In migratory birds breeding early usually leads to more offspring, but when the weather in early spring turns nasty,  the price is sometimes  death. In highly variable seasonal environments, an optimal date to breed is hard to predict, so rules of thumb are in…

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