October 25th   Leave a comment

Yesterday I saw a flock of 18 grey partridges crossing the pasture field by the airfield. This is one of the largest I have ever seen around Crail. Grey partridges form flocks in the winter, the size being dependent on how successful they were at breeding in the previous summer. If all goes well they have many chicks and so go into the winter with a large group size. This then makes it easier for them to survive the winter. With the many eyes of a large group, an individual can spend much more time feeding out in the open winter fields and can rely on its companions to spot sparrowhawks, harriers or buzzards. It’s a double gain of more feeding time and a less chance of being surprised by a predator. The partridges will keep this advantage right through until March when they split their coveys into pairs and become territorial. The gains of avoiding predators are then not outweighed by the costs of sharing everything, and the spring vegetation provides more cover. But during the winter flocking may be the only way they can survive. If the local partridges have a bad breeding season and go into the winter with a small group then they may be further reduced because they can’t share the vigilance and so maintain their feeding rate. It’s a spiral downwards in numbers that may lead to local extinctions. The root cause of the decline may well be poor breeding conditions – a wet cold summer or too much spraying so there are few insects, but the final nail in the coffin may be predation. Or due to a final twist, starvation in cold weather because the partridges cannot maintain body condition and so cannot exploit more exposed areas for fear of the predators. A flock of 18 looks well set for the winter – I think the Crail grey partridges will be alright.

Grey partridges set for the winter in a good size covey

Grey partridges set for the winter in a good size covey

Posted October 25, 2013 by wildcrail in Sightings

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