May 28, 2012

Slow start of breeding 2012

The breeding season on Lundy is in full swing now! Isabel is on Lundy since the beginning of May, and watching all our sparrows very closely. However, it turned out that the cold weather this spring  was problematic, - this year's timing of breeding is the latest on our record! The first egg of 2012 was laid at the very end of April, which is exceptionally late for the sparrows on Lundy. In 2001, they were as late, but the season picked off pretty quick in the beginning of May 2001 while this year, there were no more broods for another two weeks. Now, by the end of May, most sparrows have caught up with the good weather and we have some twenty active broods now, with the first chicks hatching now.

The reason for the unusual late timing of breeding might be the weather, - the cold spell in April prevented many insects from hatching and reproducing, too. Insects are the main food for sparrow chicks, and in a year like this, sparrows would not have been able to feed their chicks much earlier than now. The lack of insects also affected other species, - a lot of swallows were found dead on Lundy, too, and those who did survive were in a bad condition. Clearly, a cold spring can have severe consequences for birds. 

 Figure 1: The date of the annual first egg on Lundy. The red dot represents 2012. The dates are days from Januray 1st. 

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