Sweden... Part 2

As promised, the peak of our season hit us like a tidal wave! And due to a late season, it happened towards the end of the field season, meaning that we were still doing fieldwork the day before we left!

Hatching day!

My last post was (I think!) before we had any babies. Well, we had plenty by the end of the season! Thanks to the long term study of these birds, we knew that they would lay 6-7 eggs, incubate for 12-14 days then the eggs hatch usually within 2 days. So, as soon as we found eggs in a Flycatcher nest, we had a rough idea of when they should hatch. To limit the disturbance to the nest, we only visited before the hatching date in order to catch the female while she was incubating. This was reasonably straight forward, and resulted in an almost 100% success rate! We caught the females to give them a ring, determine species, age and to take biometric measurements and DNA samples, which was all entered into our data program at the end of the day/ week/ season/ whenever someone had a few hours spare!

Welcome to the world, little one!

The season was doing weird and wonderful things - started off warm, birds arrived, started making nests, then disappeared! It turned cold, a bit wet and still no eggs. It warmed up (still a bit wet), and still no eggs! Eventually, with the bribery of a crate of beer, the first nest with eggs was found (not surprisingly by the person offering the beer!) and the season got into swing. But because of the delay (assumed due to the weather), it meant that both species decided to lay at more-or-less the same time - usually the Collared's lay before the Pied's. This meant that our peak would be short and busy instead of long and easy-ish.




By this time, we were only visiting nests that had Flycatcher nests in, ever hopeful to find eggs! So our area visits weren't taking as long because we were only visiting less than half of the boxes (tits moved into most of the boxes!) The first hatch checks meant a lot of head scratching to determine if they had hatched today or yesterday! This was easier when done first thing in the morning before they had fat little bellies full of caterpillars and the parents had tipped the egg shells out of the nest!

Great Tit babies

Blue Tit babies

Day 6 chicks - bit of variation between big and little!

The chicks grew quickly, so by Day 6 they were mostly big enough for a ring and to have DNA and some measurements taken. We then visited again on Day 12 to repeat the measurements to show growth rate, and then again on Day 15+ to check if they had successfully fledged. Between Day 4 and 8 we would try to catch the male using a trap in the box. Males feed the chicks as often as the females, so this should have been relatively straight forward! However, males also appear to be trap-shy, and would hover in front of the box, see the trap and think of plan B. We witnessed several males landing in the hole and dropping food into the chicks without actually going into the box. Clever guys, but left us very frustrated! And of course, being polygamous we also had single parent nests (presumably the second female for a male).



When trapping for adults, I started singing "Silence is Golden" by The Tremeloes because if you could hear alarm calls the chances were that they'd sussed a trap and were sitting there complaining about it. If they had been caught, they would sit quietly in the box awaiting their fate - in this case, a new ring, some measurements and a drop of blood less.

Now, in a perfect world, our study birds would hatch all their eggs, rear all their young and fledge all the chicks. Unfortunately, nature had other ideas! Over half of our boxes were predated, with the main suspects being Pine Martens and Woodpeckers (except at Lilla Hult, where Cows knocked many boxes off the trees, despite being very high!) Most of our boxes have a predator cage around them to protect against Woodpeckers, but we think this might have helped the Pine Martens to climb onto the boxes. Vickleby already had a reputation for being "where things go to die" and it was certainly true - I think 95% of the boxes were predated at either egg (mummy makes a nice easy snack and the eggs wash her down nicely) or chick stage (fat little babies!). It was disheartening to arrive at a box to hear the parent alarming and find the nest empty, or the remains of chicks in or around the box. I remember checking a box which had a single D6 chick in it, which was very close to another nest with 7 babies around D10. As I approached, I noticed the complete silence around the D10 nest and went to investigate... a dead male on the ground with two chicks, three dead chicks in the nest and remains of the rest around the tree. From then on "Silence is Golden" was no longer a good song to sing.

Pine Marten calling card - apparently our rings don't taste very nice!

Carrion Beetle munching on the parent Flycatcher.

Another curious incident occurred at the end of the season. I had recorded a nest as predated after walking past one day (chicks would have been D9) and finding a leg with a ring on the roof, and another ring on the ground. The ring on the leg had been bitten flat and when I pulled it off the leg, part of the bone was stuck in there. Back at the house, that ring was found to have come from a chick from that nest, and the other was the female, so we assumed they had all been predated. As this was one of our study nests, at the end of the season we went back to do a habitat survey of the area. When we arrived at the box, there was a rather large Pine Marten poo on the roof of the box! After discussing the toilet habits of predators, I suggested we check it for rings. Sure enough, between the feathers and fine bones we found a ring! Back at the house (and after cleaning in ethanol!) we checked the number and were surprised to find it belonged to a female from a box about 500m away. This box was special because it was found with 11 eggs (average is 6-8). When we observed the nest, we found two females had laid their eggs in the same box and were sharing incubating the eggs, with one male responsible for them! Unfortunately, due to this unnatural occurrence, when we returned to the nest to take D12 measurements, there was only one chick left; presumably the others were older and had already fledged.

Anyway, we did see some Day 12 chicks, and they were very cute and very fluffy! I was even fortunate enough to see some considering fledging, which was very exciting just watching a little beak popping in and out of the hole trying to decide if it was safe. Due to the parents alarming, we left without seeing the outcome, but I'm confident that those little guys will be back next year!

Day 12 chick - right before he flew out of my hand!
Recovered about 10m away and safely deposited
back in the nest with siblings!

Day 12 chick - ringed, measured, DNA sampled,
and ready to go back in the nest.

At the end of the season, we had a celebratory BBQ with the North and South Teams, where the students put together some presentations on their work, and we drew up some numbers for the South Team season! Seeing all our hard work written as numbers on a blackboard really hit it home how much we'd done in a very short space of time!

South Team figures 2014, with our leader Eryn!

I'm looking forward to seeing some of the results of our work in papers over the coming years, and hope that I might return to Öland one day to admire the Flycatchers once more.