Birds Can Detect Predators Using Smell

Many animal species detect and avoid predators by smell, but this ability has largely been ignored in the study of birds, since it was traditionally thought that they did not make use of this sense. However, it has now been discovered that birds are not only capable of discerning their enemies through chemical signals, but that they also alter their behaviour depending on the perceived level of risk of predation.

The use of smell to detect chemical signals can be useful for birds in various situations, such as feeding and orientation. However, they can greatly increase their chances of survival if they can tell whether or not the smell they have detected is associated with a predator. Luisa Amo de Paz, the study’s lead author, explained that: “Birds can detect the presence of a predator” thanks to their sense of smell. Working as a biologist at the Spanish National Research Council’s (CSIC) Natural History Museum while the study was carried out, Ms. Amo de Paz is currently working for the Netherlands Institute of Ecology (NIOO-KNAW).

The research, published in the latest issue of Functional Ecology, provides the first ever evidence to show that birds are able to distinguish their predators using chemical signals. According to the researchers at the CSIC’s Natural History Museum, this study “opens up a new and promising area of research in understanding numerous aspects of bird behaviour, which have been ignored until now.”


Lees meer: Science Daily

Birds announce their sentry duty to help comrades get a good meal

Soldiers on sentry duty in hostile territory keep in regular radio contact with their colleagues to assure them that all is well and that they are safe to carry on their manoeuvres. New research funded by the Biotechnology and Biological Sciences Research Council (BBSRC) and published in Current Biology today (17 April) reveals that this is also a feature of the bird world and is very likely to be a rare example of truly cooperative behaviour.

Researchers from the University of Bristol, led by BBSRC David Phillips Fellow Dr Andy Radford, have demonstrated that by giving the distinctive ‘watchman’s song’, individuals scanning for danger as sentinels ensure that their group-mates can focus on foraging, and so capture more food. Dr Radford said: “These exciting results point to a great example of true cooperation. The unselfish behaviour of the sentry is probably rewarded down the line by the improved survival of group mates, which leads to a larger group size. This increases the sentinel’s chances of survival when the group is under attack from predators or having to repel rivals from their territory. It’s a win-win scenario!”


Lees meer: Biology News

Migratory Birds Make Mistakes In Direction, But Not Distance

Migratory birds make mistakes in terms of direction, but not distance. These are the findings of a team of ornithologists and ecologists from the University of Marburg, the Ornithological Society in Bavaria and the Helmholtz Centre for Environmental Research (UFZ), writing in the Journal of Ornithology. The scientists assessed several thousand reports of Asian birds from the leaf-warbler and thrush families that had strayed to Europe. They discovered that the distance between the breeding grounds in northern Siberia and the wintering sites in southern Asia was often similar to the distance between the breeding grounds and Europe. The more similar the distances and the more numerous a particular species, the higher the probability of this species of bird straying to Europe.

Lees meer: Science Daily

Effect of nestbox type on occupancy and breeding biology of Tree Sparrows Passer montanus in central Spain

Auteur(s): Garcia-Navas, V; Arroyo, L; Sanz, JJ; et al.
Bron: IBIS 150 (2): 356-364 APR 2008
Abstract: Avian life-history studies are often conducted on populations nesting in nestboxes. However, the type of nestbox used is a potentially confounding variable, as each model shows specific characteristics.

In recent decades, a new commercial model of artificial nestbox made of woodcrete, a mixture of sawdust and additives, has become popular owing to its better protection against predators compared with the classic wooden design. We assess the effect of nestbox type on the breeding ecology of Tree Sparrows Passer montanus, focusing on their thermal properties, an influential factor in nestbox selection. Occupancy rates and reproductive parameters of Tree Sparrows were compared between birds breeding in woodcrete and wooden nestboxes over 5 years.

Woodcrete nestboxes had a higher occupancy rate and birds breeding in them had earlier clutches, a shorter incubation period and more reproductive attempts per season than birds nesting in wooden boxes. Clutch size and nestling condition did not differ between nestbox types, but reproductive success was higher in woodcrete nestboxes. The higher temperature in woodcrete nestboxes (1.5 degrees C higher on average) might explain these differences. Such differences may bias results obtained in comparative studies where more than one nestbox type is used.

Birdfeeders Can Both Help And Harm Bird Populations

Millions of people tend bird feeders in their backyards each year, often out of a desire to help the animals. But a new survey of research on the topic finds that feeding may not always bring a positive outcome for the birds.

In many cases, bird feeding was shown to have immediate positive outcomes. A number of studies indicated, for example, that chicks which were given supplemental food were far more likely to fledge than those that were not given extra food.

But feeding is a complex business and can lead birds to make poor decisions later in life. Attractive feeders can become ecological traps, encouraging birds to settle in an area that cannot support them once supplemental feeding has stopped. In those cases, feeders create a population level that cannot be sustained by natural levels of food.

Lees meer: Science Daily

The Song Doesn't Remain The Same In Fragmented Bird Populations

The song of passerine birds is a conspicuous and exaggerated display shaped by sexual selection in the context of male-male competition or mate attraction. At the level of the individual, song is considered an indicator of male 'quality'.

Paola Laiolo and colleagues at the Spanish Council of Research (CSIC) studied the metapopulation system of the Dupont's lark in north-eastern Spain and found an association between individual song diversity and the viability of the population as a whole, as measured by the annual rate of population change. This association arises because males from the most numerous and productive populations, i.e. those less prone to extinction, sang songs with greater complexity.

Lees meer: Science Daily