The big news this week concerns winged animals but not birds – they are painted lady butterflies which were recorded in unprecedented numbers throughout Shetland.
These strongly-flying migrants are part of a national phenomenon.
I mentioned a painted lady being seen at Twatt last week. This may have been a migrant, but painted ladies are also sold in butterfly-rearing kits which are popular with schools and individuals.
The stages of development from egg to caterpillar to chrysalis to adult can be studied, before releasing the adult butterflies.
However, on 21st May large numbers of these orange coloured butterflies were seen flying in off the sea at Portland Bill in Dorset. Over the next few days, helped by the fine weather and southerly winds, thousands were seen arriving all along the south coast of England. Hundreds were recorded in central London, while an estimated 18,000 were seen flying past Scolt Head Island in Norfolk.
By Sunday 31st May, the painted ladies reached Shetland in considerable numbers, with widespread reports of these strong-flying migrants.
This huge influx of butterflies was predicted by scientists. Last winter, heavy rains in the Atlas Mountains of Morocco allowed a greater than usual germination of the seeds of the food plants which the caterpillars feed on. This increased food supply resulted in huge numbers of adult butterflies which then migrated into Spain and through Europe. It is thought that this could be one of the biggest painted lady migrations for decades.
We were enjoying the view from a hill in the West Mainland on 1st June, when we heard ravens croaking loudly. As they neared, we could see that a pair was mobbing a huge bird of prey – a white-tailed eagle. I have seen these magnificent birds on the island of Rum, but not in flight.
First it flew below the level of the hill, giving us a superb view, and then rose up and flew over us. At this point, having a bird with a wing span of two and half metres directly above, the phrase “a flying barn door” came to mind.
The eagle then settled some 100 metres away but it was continually harangued and harassed by the ravens dive-bombing. After a few minutes they settled close by, making quick sorties to peck at its tail feathers.
The white-tailed eagle moved along the hill twice more, followed by its pursuers, which were joined by a pair of common gulls. Eventually it flew over the ridge of hills, hopefully finding a more peaceful spot. A white-tailed eagle was seen flying north over Virkie on the 31st but there is a possibility that there are two of these impressive birds around.
Birds of note this week include the nationally rare laughing gull, still in the South Mainland and the lesser scaup at the Loch of Houlland. Other locally rare species which are still around are a subalpine warbler, the honey buzzard and the little egret.
There was a common crane at Watsness, present there for over a week. Small migrants included tree pipit, turtle dove, chaffinch, icterine warbler, marsh warbler, spotted flycatcher, golden oriole, hawfinch and common redpoll.
Many birds are incubating or bringing out young now. It is important not to disturb nesting birds as eggs and chicks can be quickly taken by predators. Some species, such as the red-throated diver, require a special permit to be approached on or near their nest. Scottish Natural Heritage on (01595) 693345 can provide details of the legislation which applies to breeding birds.
Killer whales have again been sighted this week – this time along the Lerwick/Fladdabister and Bressay/Noss coastlines.
Volker Deecke of the killer whale research team reported that it was the same group of five which were identified last year, and the only group they have seen so far this year. Identified by photo the members were Busta, Linga, Lunna, Billan and Ossa.
Volker said that the group spent a lot of time swimming right next to shore, which is typical behaviour for this pod. Near Loder Head they made an attempt to wash a seal which was hauled out on a rock into the water, but were unsuccessful.
Aside from a few echolocation clicks and high-pitched whistles, the whales were again largely silent throughout the encounter, which is consistent with hunting prey which has acute underwater hearing, such as sea mammals.
Volker and the team would be very grateful for any information on sightings of killer whales around Shetland. The telephone number to contact is 07500 380524.
Joyce JM Garden