Will we be invaded?

Most, but definitely not all, winters see the arrival of a scarce irruptive species (or two or three) in the Oslo area. The classic species are Pine Grosbeak, Two-barred Crossbill, Hawk Owl and new to the list Great Grey Owl.

We currently have a good berry crop especially on planted asal trees in urban areas such that we can hope that if Grozzas do irrupt this autumn then we at least have food for them.

berry laded trees on this morning's dog walk. I can never remember quite so many berries on these exact trees

We had none last winter but proper invasion winters in 2024/5, 2021/2022, 2019/2020, small numbers 2017/2018 and 2016/2017 and good numbers in 2012/2013 when there were no berries but they fed on fresh shoots in spruce trees.  Two-barred Crossbill is far less regular but we had good numbers in the winter of 2019/2020 which was a good crossbill winter in general due to a lots of cones but should they also arrive when there are not cones then they may find other food such as in the winters of 2014/15 and 2013/2014 when small flocks fed on some ornamental seed stones in the Oslo Botanical Gardens.

Owls irrupt following good breeding seasons which means there are a lot of owls and then a collapse in rodent populations means little food and causes the owls to spread out looking for places where there is food. Hawk Owl has long been a species that can turn up around Oslo and does so pretty much every 4 years with a bird two winters ago in Maridalen and multiple birds in the winters of 2020/21 and also 2019/20, 2016/2017 and 2012/13. It is therefore not to be expected that we have a bird this winter but of course not impossible. Great Grey Owl is so new as a breeding species in southern Scandinavia that we have no history with which to make predictions and it is only the winter of 2019/20 that we have previously had the pleasure of their company in Oslo. However, it is clear that they irrupt in the same way as Hawk Owl with good breeding seasons followed by rodent population crashes causing them to wander.

Great Grey Owls had a very good breeding season in their core area last year which I was able to enjoy but less successful this year as rodent numbers had already started to decline. Rodent should now be hitting the bottom of their 3 to 4 year cycle meaning there are good numbers of owls needing to find food. There have already been reports from the coast suggesting birds are on the move so my hope has, for quite a while, been that this winter will again host GGO in Oslo. We also have lots of new clearings due to extensive forestry work and these provide ample (perhaps too ample for the birder wishing to find one) hunting grounds for the owls. The only remaining blocks that have to fall in place are for there to be enough rodents around Oslo to sustain an owl or two during the winter and for the owls to find them and decide to stay.

There have been no signs that this summer has been good for rodents with Tawny Owls being unusually hard to hear in Maridalen but intriguingly there have been a small handful of reports of Great Grey Owl from the Maridalen and Lillomarka area since last November. Some of these were third or fourth hand reports that were difficult to know what to make of but there have been some photographed birds. I am certain that there has not been breeding but rather wandering young bird(s) from last summer’s good breeding season further north have made it to the Oslo area and are scratching a living.

A report of a bird on Sunday with photographs clearly taken with a mobile phone of a bird hunting in the day in Lillomarka was interesting and exciting. Was it the same bird that had been reported those handful of times or was is a new wandering bird and the vanguard of the invasion I have hoped for? We can of course not know for sure but developments through the late autumn will give us a clue.

I of course went looking for it yesterday morning and for once took the Beast with me as a long and potentially unrewarding walk in the woods would be made more enjoyable with some company and as he now approaches late middle age he has become a bit easier to take birding. Also, he would hopefully be a lucky charm as his breed name Finnish Lapphund shares the same Lapp name as Great Grey Owl in Norwegian (lappugle). A bit convoluted I know but I will take all the help I can get.

We didn’t find it in our first check of the area where it had been seen the day before and continued through the forest checking out where Honey Buzzards had bred this year in a new nest but which I had not previously visited due to my far more accessible nest in Maridalen. Coming back a couple of hours later though there it was perched very openly on a tree stump just as they are supposed to do. There then followed nearly three hours of observation when I watched it make four succesful catches all of which it ate on the ground so I could not see exactly what it caught but once did see a long tail sticking out as it swallowed the prey. After the first three catches it resumed hunting immediately and it was only after the fourth that it seemed sated enough to relax and preen. It had clearly found an area with, for the moment at least, good numbers although the fact it is hunting so much during the day in such an open area does suggest that the bird is both very hungry and that there are not many rodents as otherwise it would hunt within the forest as night.

It will be interesting to see how long it stays but I doubt the one small area where it was can have enough food to sustain it for too long so it will surely soon move on although maybe not far.

I continued my long track record of failing to press record when I thought I had so do not have digital memories of some of the scenes I witnessed but have managed to capture some hunt and flight sequences.

Great Grey Owl (lappugle)

much too low shutter speed but I don't think anyone would expect anything else of me :-)

well camouflaged in black and white

it very clearly has two generations of primary and secondary feathers which I interpret as meaning it is a bird born last year with a mix of juvenile and adult feathers

some pics from the phone including an obligatory selfie

lapphund og lappugle

Au revoir GG?

On Thursday I guided to Great Grey Owls for what will probably be the last time this season. The chosen bird was Miss Hissig, the unusually vocal female who has always made her presence known by bill snapping whilst we are more than 50m away. On Thursday she had also added a rather menacing growling to her repertoire and this may have been due to the presence of a fairly large young on the nest. We kept a respectable distance and didn’t place ourselves between the female who was perched high in a pine about 25m from the nest and the nest itself. There was also the possibility that there was a young on the ground and should one approach such a bird too close then the chances are very high that the female will attack (it is this instinct that ringers use to catch the adult females with a large net). We clearly chose an acceptable spot to stand as she soon became quiet although any noise or perhaps movement elsewhere in the forest could attract her attention and start a series of growls and snaps.

We hoped to see the male arriving with food but early afternoon was never going to be the best time although at one stage the youngster became very animated and started calling excitedly which I felt certain was going to prelude dad flying in (mum had also looked excited) but nothing happened. The young which had been out of sight when we arrived became more and more active during our stay so was I assume getting hungry. It also rained briefly which I thought would cause mum to fly to the nest to cover the young but that did not happen either. This female really is a strange beast but it hasn’t stopped her, or perhaps more importantly her mate who brings the food, from raising a youngster to very close the jumping out of the nest stage in a year where voles are clearly in short supply.

The excited calling from the nest at one stage sounded like it was coming from two birds so the single large bird we saw may also have a smaller, younger, sibling that was not yet large enough to peer over the edge of the nest platform.

The video included sequences of mum bill snapping and growling (good speakers may be necessary to hear this) and the youngster calling excitedly.

I am very excited to see how this winter and spring of next year will pan out. If vole numbers crash then we could see Great Grey and other owls spreading around looking for food and then we may be lucky enough to have an owl winter around Oslo. Should this happen though then the chances of spring 2027 being good for singing and breeding owls is low. Vole numbers may however hold up for another season meaning next spring is similar to this, i.e owls breeding but at low densities and with few young. Only time will tell.

Satisfying guiding

Two very enjoyable and successful days of guiding different clients (Martin from Edinburgh and Andrew and Merril from New Jersey) have given some very nice birds. There was a large grey owl in the mix on Sunday and today was a morning of Oslo’s finest including Hobby, Rosefinch, Marsh & Icterine Warbler, Wryneck, Hawfinch, and all three species of Flycatcher 😊.

 

As usual when guiding I took very few photos and just used the superzoom so my digital output does not do justice to the two days.

something was watching us

is that a Robin?

no, it is Oslo's first reported Red-breasted Flycatcher since 2019. This species seemed to be on the cusp of establishing itself as a regular breeder and then just stopped appearing

More good guiding

I am just off the back of another two very enjoyable and successful days guiding. Wednesday was Hedmark Owls and a short and sweet best of Maridalen with Rob and Helen from Blighty and today was an Oslo highlights trips with Andy from New York.

Many good birds, good experiences, deep discussions and laughs were had. The best birds were of course Great Grey and Ural Owl plus Black Woodpecker and Wryneck on Wednesday and then on Thursday, Oslo (and suburbs) could offer amongst (many) others Thrush Nightingale, Honey Buzzard, Goshawk, Black-throated Diver (or Arctic Loon if you are so inclined), Temminck’s Stint, Velvet Scoter, Marsh, Wood and Icterine Warblers, Common Rosefinch and of course Black Woodpecker and  Wryneck. The bird that got me most excited though is one that will never appear as a “tick”. It was clearly a Branta goose and at first glance I was thinking Cackling Goose but after a bit more study it was clearly a hybrid between Barnacle Goose and either Canada or Cackling. I think Canada is the most likely other parent as it was not as small as I would expect a Cackling hybrid to be (I have previously seen one of these in Oslo in 2018) and lacked a throat collar. There is a population of feral Branta hybrids in Holland and these birds are very likely to come from there.

My own pictures are getting worse and worse but give an idea of what we witnessed. The video is from today with snippets of Thrush Nightingale, Temminck's, Rosefinch and the hybrid goose.

the lady

a high Honey Buzzard (vepsevåk) over Maridalen. Probably a female

presumed hybrid Barnacle x Canada Goose (hvitkinn x kanadagås) with Canada Goose in Sørkedalen.

The Ugly Owlet. Ural Owl (slagugle). Not long until this youngster makes the big jump

Golden (Bread) Guiding

Rest, they say, is only for the wicked (as has been pointed out to me I have got that expression completely and rather embarrassingly wrong! It is of course NO rest for the wicked…😂) and this bank holiday has seen me guiding for southern Norway’s best birds which at the moment primarily means owls. I have spent three long, tiring, but very fun, and rewarding days with Graham and Marcus Workman where were have seen Great Grey, Ural and Tegnmalm’s Owls, Black Woodpecker, Wryneck, Honey Buzzard, Common Rosefinch, Icterine and Wood Warblers, Slavonian Grebe, Moose, Capercaille and so much more.

The Great Grey and Ural were rated as their best birding experiences ever and I couldn’t possibly disagree with that.

All the birds that I have been monitoring and checking in on this spring were present and correct and showed impeccably well with my only complaint to the Bird Gods being that the two singing Common Rosefinch that we found were boring brown 2cy males instead of the bright red older males that give them their name. It was only me complaining though☺️

 

I don’t have the time to write any more as I need to allow myself a rest as I am guiding again tomorrow and most of next week. I’ll just let the photos and video do the talking - it truly has been a great weekend!

This explains the Golden Bread reference. When Norwegian birders celebrate a lifer it is a tradition to celebrate with a Gullbrød (gold bread). This chocolate covered bar of marsipan is not to my personal liking but Graham and Marcus were keen to join the tradition. Here they are celebrating GGO which was lifer #1 but there were at least 3 more after that

my footage from the weekend pales into comparison with what these two got. Graham had a top of the range Nikon set up but  Marcus was just using an iphone 11 (the same as me) with an adapter on a Kowa scope and was taking fantastic videos and stills. I hope to link to their work later once they are home and have published it. And I think I will be getting an adapter - will sure be cheaper than buying a new camera and lens that I rather desperately need and to be honest may give better results

Great Grey Owl (lappugle) - this is the "hissig" female and as usual she greeted us by bill snapping and this time growling long before we could see her. Again she was perched in a tree when we arrived but then flew onto the nesting platform so presumably has eggs but once again I can only say that her behaviour is not normal

Ural Owl (slagugle) presumed female. We glimpsed the furry tops of the heads of probably two young in the hole of the nest box and the male was also in the area

it was a joy to see this young Tengmalm's Owl (perleugle) who was looking out at dusk of his own accord (i.e no need for my poor trunk scratching to be put to the test). I reckon it was going to leave the box that same night

This sequence from the Black Woodpecker nests shows first from the nest with the three young where both parents came into feed at the same time but only after we had waited for close to an hour and a half... Our presence clearly affected the behaviour of the parents though and we had to move further back before they came in and fed the young. The sequence in the video where it almost looks like they are engaged in ritual courtship is how they were acting when they did not dare to go the nest (i.e before we moved away). Right at the end is the female in the other nest where excavation seems to be over and hopefully egg laying has begun. As they are a good month later than normal it will be interesting to see if they succesfully fledge young.

male Black Woodpecker (svartspett) and young

Slavonian Grebes (horndykker):

I also had a chance to check the second Ural Owl nest box and here the female was sat high so I reckon has newly hatched young but is around two weeks behind the other pair

Checking in on the owls

Yesterday, saw me on a friends and family guiding to the owls in Hedmark. It was very successful if, as always, tiring trip.

Two nesting Great Grey Owls included my back up nest which I visited for the first time and the pair that I have now previously visited which have acted in a very aggressive way without being on the nest. On yesterday’s visit the female again announced her presence by bill snapping when we were 50m away and could not see either her or the nest. She was perched quite high in a tree and continued snapping noisily whilst we watched her. It is quite uncomfortable being there when the bird seems so unhappy/angry so we didn’t hang around but I kept looking over my shoulder as we left just in case she flew at us but instead she flew onto the nesting platform and acted very much as though she was on eggs! But this raises a number of questions:

1.      Why was she not on the nest initially? My experiences with other nesting GGO over the years has always been that the females stay on the nest no matter what.

2.      Why does she continue to be so aggressive in her behaviour? At the other nest we visited the female made no noise and hardly seemed to follow our movements

3.      Why is she so late in egg laying? The eggs (if there actually are some) must surely have been laid since my visit with Jack on 5^th May whereas I know that at the other nest the first egg was laid on 22^nd April which I think is in itself a fairly late date.

the particularly aggressive female GGO in a tree

and then suddenly on the nest platform

and the other GGO nest which is much more luxuriously furnished

A check of the Tengmalm’s nest box resulted in no joy for my trunk scratching but I was able to attach the superzoom to the tripod and lift it up such that I could see through the hole and there were at least two large young in the box. A very thorough search of the area did not reveal any adults or other young that may already have jumped out although mum must have been very close by.

 

We checked just one of the Ural Owls nests. This was the nest where the female flew out when I scratched on 8^th April so with an incubation period of about 4 weeks I was ready for the young to already be large enough that mum was no longer in the box. This meant we need to be very careful as to how we approached the area and we walked a large semi circle around the nest box. The female gave away her presence by bill snapping and when we finally saw her perched about 30m from the box she flew away from the box as though trying to draw us away. Just a couple of steps by us towards the box though brought her right back and then she kept a very close eye on us (although we did not go any closer to the box for both our own safety and also her comfort). One thing that was odd was that she seemed to be panting almost all the time. It was only about +13C so was hardly hot and she wasn’t in direct sunlight but she was pumping her throat with her bill open (but not making any audible noises) for minutes on end. The young did not show themselves in the nest opening so are hopefully not ready to leave for 1-2 weeks.

Ural Owl (slagugle)

 

A stop to listen for Ortolan resulted in no joy and although it may still be a bit too early it would hardly be a surprise if none returned this year. The last confirmed nesting was my record in 2023 and the last two years have only seen a couple of unpaired singing males, one of which is very likely to have been the male from the 2023 nesting. So, it would be no surprise if these birds are now dead and with no recruitment to this population extinction has been unavoidable.

Oslo birding since my last post has continued to be quite uneventful with rain and southerly winds having no noticeable effect. The only highlight was a thirty minute mid afternoon period in Maridalen on the 16^th just after it had stopped raining and when the sun came out. This caused a Falsterbo lite experience with 3 Honey Buzzards, 4 Ospreys, 1 Common Buzzard, 1 Sparrowhawk and 4 Kestrels moving through. Wrynecks seem to be well established though with no a mating paid and two unpaired males and after struggling with Black Woodpecker I now have a nest that is still being excavated and another where two young were being fed at the entrance. At the nest which is still being excavated I saw no splinters being thrown out but could hear one of the adults (I’m quite sure the female) knocking away inside the hole and also on two occasions drumming inside the hole!

this Black Woodpecker nest must be at least 4 weeks ahead of the other one I found

And an interesting encounter with a Beaver that just swam straight down the white water rapids