Friday, 21 December 2018

Oslo Red-breasted Flycatchers in 2018

I had a long post in December last year detailing the real life soap opera that Red-breasted Flycatchers entertained us with in 2017. 2018 was a bit less racy but there was still drama.
In 2017 we had record numbers of Red-breasted Flycatchers around Oslo including the second recorded successful breeding record. In the regular Sørkedalen locality we had two singing males but no sign of a female and in Maridalen we also had two males plus a female (who at various times was paired with both males) and 3 young that successfully fledged along with four young Pied Flycatchers that believed their dad was a Red-breast… I was therefore very excited to see what 2018 would bring. How many Red-breasted Flycatchers would return, and would there be some Pied Flycatchers that sang like a Red-breasted Flycatcher?

I have already alluded to the fact that Red-breasted Flycatchers did indeed return and last years old male returned to Maridalen on 8 May which made him the first bird recorded in Norway in 2018 and must be considered an early date regardless of year. The black spot in the left eye ring confirmed his identity.

He sang in vain for a long time and checks of Sørkedalen revealed no birds there so it looked like 2018 was going to be a shadow of 2017 but finally on 24 May a female turned up (she was definitely not around on 22 May based on the males behaviour but could have arrived 23 May when I did not visit). She was a very well marked bird (old?) with an orange wash on her throat which meant I initially thought she was a 2cy male. I was able to watch their courtship which included the male taking her to potential nest sites which she tested out. Things developed very quickly and the female soon disappeared and the male stopped singing all of which indicated she was on eggs but it was not until 5 June that I located the nest.

The nest was in exactly the same type of place as last year – at the base of a piece of bark that was falling off a tree. This looks such a precarious site but was successful last year and perhaps does suggest that it is the same female? I followed the nest as regularly as I could and it was lower than last years so easier to see but the female was so deep in the nest that all that could be seen was her tail or beak tip. It wasn’t until 15 June that the behaviour of the birds changed and it seemed clear that young must have hatched. I put the camera on the extended tripod and holding this over the nest was able to get a picture showing three just hatched young and three eggs!

With an assumed incubation time of 14 days then the last egg would have been laid on 1 June and with 6 eggs (and one egg laid per day) then the first egg would have been laid on 27 May. With the female arriving on 24 May (possibly 23rd) then they must surely have started nest building already that day if they were to be able to lay eggs just 3 days later (BWP gives nest building as 3 days).

On 16 June both parents were coming regularly with food to the nest (although I did not try to find out how many young had finally hatched). A visit on 21 June revealed disaster though. The bark and nest had fallen down and were lying on the floor. This had probably happened a few days before and there were no remains of eggs shells or young. Why did this happen? We had some very strong winds that could have blown it down but a predator such as a Red Squirrel of Great Spotted Woodpecker could easily have caused this damage.

This was of course not the outcome we wanted but nest failure is part of the game and research in Poland showed that only 51% of clutches resulted in at least one fledged youngster and of the failures 82% were down to predation.

The male was heard singing in the area again on 22 June and then on 24 June I saw the pair engaged in courtship behaviour so a second breeding attempt seemed to be on the cards despite the late date but we had no more observations after 28 June so don’t know what happened.

Although I did not observe or hear any Pied Flycatchers that I suspected were the ones raised by the RB Fly last year there was a female Pied Fly that raised young alone (as far as I could see) and I did see the male Rb Fly around her nest box. I did not see any interaction between the two birds but he did react aggressively to a male Pied Fly in the area so he may have been up to his old tricks.

Some interesting papers on Red-breasted Flycatchers in Poland:

the same old male as last year, individually identified by the black spot in the bottom of the right eyering

large caterpillars were definitely the prefered food
although smaller insects were also eaten

the nest site

the female. She was unusually well marked on her throat and upper breast which is presumably a sign of old age 

the male coming with a rather large larvae on 15 June the days the young hatched

male and female on the nest

the nest from above

three very newly hatched young and three eggs

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