Extreme Percentage change

Terns flying near warf post

“While it is normal for seabirds to suffer periodic failures, the frequency seems to have been increasing in recent years.”

  • 45% of EU seabirds nest on the coasts of Scotland
  • On St Kilda only 26% of Puffin burrows produced chicks compares with 71% in a ‘normal’ season
  • Canna’s kittiwake colony of about 1 000 pairs saw 5 chicks leave the nest, and on Eigg only 15 kittiwakes were seen against 5 000 normally
  • At Ceann a’ Mhara 2,173 birds were found in a census but only 4 guillemots chicks were seen against 1,500 chicks in a ‘normal’ year
  • On Papa Westray 1050 adult arctic terns were seen but only one chick, Fair Isle reporting a complete failure – no chicks

The common pattern appears to be that late breeding species are doing badly. A shortage of sandeels – a common food source – caused low numbers last year, but this year some observers have noticed species looking for alternative food sources such as white fish (pollock), but this food has less nutritional yield for the chicks.

Your turn

  1. Calculate the percentage drop in guillemot chicks compared with a normal year
  2. Calculate the percentage of kittiwakes seen on Eigg compared with a normal year

These are very small percentages – for the second year running – hence the concern

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