Tuesday, 27 July 2021

Back in Oslo

We have bid farewell to the mountains and are now back in Oslo.

The last couple of days in Beitostølen gave some good birds with an alarm calling Temminck’s Stint leading me to a well hidden and motionless youngster. A couple of noisy juvenile Merlins led me to their nest and 3 Siberian Jays showed well on a dog walk.

Mountain Fritillaries started flying in enormous numbers by the end of the week and my daughter picking up 30 dead ones (undoubtedly killed by cars) from a 50m length of road gives an indication of how many were on the wing.


Back in Oslo my focus is still on butterflies and I have decided to try to find out the distribution of White-letter (almestjertvinge) and Purple Hairstreak (eikestjertvinge) close to my house. White-letter is listed as Vunerable on the Norwegian red list and while Purple is not listed it is rarely reported and Oslo is at the northern limit of where they are known to occur. Both these species have previously been reported from Oslo before but very infrequently although the trees they lay their eggs on: elm and oak are numerous in gardens and parks where I live so I have always thought they should be around. I have normally been away from Oslo in July when they fly which might explain why I have not noticed them before but both species also spend most of their time in tree tops so are species one doesn’t normally just bump into. There are two other species of hairstreak in Norway and surprisingly enough I have actually seen both in the garden. Brown Hairstreak (slåpetornstjertvinge) is listed as Near Threatened and turned up one August whereas Green Hairstreak (grønnstjertvinge) is a common species in the forests around Oslo but not in the city (seen in May).

I asked for advice on Facebook as to how I could best find the species and was advised that White-letter at least could be found on thistles close to elm trees. Well, that hasn’t worked out for me (yet) but by scanning over oak and elm trees I have now found hairstreaks twice. It is only elms that have turned up trumps and two separate elms have had three small butterflies flying fast and erratically around them high up. Taking pictures to ascertain species has been difficult but at both trees I have managed to photograph two individual butterflies and in both instances they have been one each of the two sought after species! Quite why Purple should be flying around an elm tree with White-letter is a mystery to me but maybe butterflies attract each other and it could be the trees are especially rich in honeydew secreted by aphids and apparently the favourite source of energy for both species.

We now have two days of rain but the search will continue when it is dry and sunny again. Maybe as the season wears on the butterflies will fly lower down and nectar on thistles allowing some good photos.

adult Temminck's Stint which engaged in a distraction display when I walked past

and this was the reason why - a half grown youngster

young Merlin (dvergfalk) perched by nest

two youngsters

Siberian Jay (lavskrike) where I had them last time and proving that this is a reliable spot

dead Mountain Fritillaries (fjellperlemorvinge) collected by Jr Jr along a 50 long stretch of road

and a live individual which was spending the night (picture taken at 9.30pm) on some sorrel 

comparison of the underwings of Cranberry Fritillary (myrperlemorvinge) left and Mountain Fritilary - quite similar aren't they!

Cranberry Fritillary

we found lots of cloud berries (multer) but unfortunately and very annoyingly the majority were not yet ripe. There are some very interesting butterflies that specialise on this plant but I failed to find them

my best picture so far of White-letter Hairstreak (almestjertvinge) high up in an elm

and a Purple Hairstreak (eikestjertvinge) which landed on a Norwegian Maple (spisslønn) leaf

and this large elm held both species

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