Wednesday, 10 June 2015

Sad timing

A ptarmigan nest site on a high hillside - but look closely

It's a busy busy time of year for fieldwork in the Highlands at the moment and although the weather has improved, there have been some casualties from the previous week's storm. One such, which I have found, was this clutch-brood of ptarmigan.

The nest after the chicks had hatched and the hen had led away her surviving chick
I was up in the hills surveying and checking on the progress of a population of ptarmigan that I have been studying for many years now. Their numbers were low and as the birds were sparse, they were a bit difficult to find, but I did confirm that there were three pairs in the area. The males were all in one flock as they tend to leave their hens about the time when the chicks are due to hatch. And I found a nest where the hen had hatched her chicks.

Two unhatched eggs and a dead chick, which had never dried after hatching, were left in the nest.

I immediately saw that all was not well. There were two unhatched eggs in the nest along with a dead chick and another dead chick lay outside the nest. This was on the Wednesday and there had been a wild storm on the Monday - the day the chicks had hatched. The embryos in the two unhatched eggs had probably died during the cold wet weather that the hen had to sit through while incubating. I have seen eggs fail to hatch in similar circumstances before. Even ptarmigan, which can endure snow storms while incubating, cannot keep all their eggs warm throughout prolonged cold weather.

One chick which had dried after hatching was found dead about a metre downhill from the nest.
Left behind as it was too weak?

Such bad timing. If the chicks had only hatched the following day, the hen could have perhaps saved the two chicks which likely died from hypothermia during the storm. However, there were remains of three hatched eggs, so the hen seemed to have led one chick away safely, so all were not lost. And the good news is that two other hens were still sitting on eggs so their chicks should have a better start now that the weather is warmer. Although, it needs to warm up quickly as the vegetation, including the chicks' main food plants, blaeberry and small herbaceous species, have only now began to open their leaves, and there are still very few insects in the area to supplement their diet.

This ptarmigan was still incubating her eggs, hopefully they will hatch while the weather is warmer and drier.

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