Researchers Crack Cuckoo Egg Mystery

Researchers at the University of Sheffield have discovered that cuckoo eggs are internally incubated by the female bird for up to 24 hours before birth, solving for the first time the mystery as to how a cuckoo chick is able to hatch in advance of a host´s eggs and brutally evict them.

Published September 22, 2010 in the journal Proceedings of the Royal Society of London, Series B, the research shows that internal incubation allows the cuckoo chick to hatch before its nest mates, evict them, and monopolise the food brought by the foster parents.

Although previous studies have suggested early hatching is achieved partly through the cuckoo producing a small egg which develops faster, it has long been suspected that there might be another reason for this.

Lees meer: ScienceDaily

Night Light Pollution Affect Songbirds' Mating Life, Research Suggests

In today's increasingly urbanized world, the lights in many places are always on, and according to a report published online on September 16 in of Current Biology, a Cell Press publication, that's having a real impact on the mating life of forest-breeding songbirds.

"In comparison to chemical and noise pollution, light pollution is more subtle, and its effects have perhaps not received the attention they deserve," said Bart Kempenaers of the Max Planck Institute for Ornithology in Germany. "Our findings show clearly that light pollution influences the timing of breeding behavior, with unknown consequences for bird populations."

The researchers investigated the effects of artificial night lighting on dawn song in five common forest-breeding songbirds. In four of those five species, males near street lights started singing significantly earlier in the morning than did males in other parts of the forest.

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Communication across territory boundaries: distance-dependent responses in nightingales

Auteurs: Philipp Sprau, Tobias Roth, Rouven Schmidt, Valentin Amrhein, Marc Naguib
Bron: BEHAVIOURAL ECOLOGY, Volume 21, Issue 5, p. 1011-1017
Abstract: In communication, vocal signals are often used for long-range signaling. Yet, little experimental evidence is available on the role of territorial signals across territory boundaries and their effectiveness at different propagation distances. In many songbird species, song overlapping and rapid broadband trills are used and perceived as agonistic signals, yet they differ in their propagation distance. Trills degrade quickly over distance, suggesting that their agonistic function may decrease faster over distance than that of song overlapping. Here, we tested whether different signaling distances of a rival affect singing responses of a territorial male and whether such distance effects differ when a rival uses rapid broadband trills or song overlapping. We exposed male nightingales (Luscinia megarhynchos) to songs of simulated rivals broadcast from 2 distances outside their territories. Each subject was exposed either to a moderate alternating playback without trills or to an agonistic playback, that is, to an alternating playback with trills or to an overlapping playback without trills. Irrespective of the treatment, males sang more songs containing trills in response to near than to far playback. As expected, males responded more strongly to the 2 agonistic treatments than to the moderate treatment. However, males did not clearly decrease responsiveness to playback containing trills broadcast from afar. This indicates that trills maintain their agonistic function even at distances at which information encoded in frequency bandwidth is degraded. Taken together, our results show that information encoded in signals used for resource maintenance is important also in communication across territory boundaries.