Zoology: Brainier birds avoid predation

Pheasants that performed better on cognitive tasks as juveniles developed larger home ranges as adults and better avoided predation by foxes, according to a study published in Nature Ecology & Evolution this week.

As animals move through their environments, they become familiar with both favourable and unfavorable aspects of their habitat — for example, resource patches and predators. Although the ability to remember these habitat dimensions would be expected to be important for developing home ranges, the link between memory and home range has rarely been tested directly.

Robert Heathcote and colleagues raised 126 juvenile pheasants and used 3 standard tests of animal cognition to measure their short-term and long-term memories: the pheasants were tasked with associating a particular colour with a food and were given 2 mazes to navigate. Once the birds were 10 weeks old, they were released into a semi-natural environment of mixed woodland, grassland and farmland in the UK. The birds’ movements were tracked with radio tags, which allowed the researchers to map their home ranges. They found that pheasants with higher scores on memory tests developed larger home ranges and had a higher survival rate when predation by foxes was measured. The authors indicate that mortality events were more common when birds were at the periphery of their home ranges, suggesting that they might have been less familiar with available refuges in these areas.

The findings indicate an important link between cognitive ability and space use in the wild. By measuring survival as a key aspect of fitness, the authors also suggest that natural selection favours birds with better memories.