Monday, 7 July 2014

The Black-headed Gull Colony- sketchbook




(Read the unofficial precursor to this post, Herring Gull Town, here!)


I wrote last time about the Black Swans and their mating dance at Titchfield Haven nature reserve, which was fascinating but what really draws me there every spring is the amazing colony of Black-headed Gulls that assembles every year on one of the scrapes! This colony is carefully protected with controlled water levels and an electric fence to deter ground predators, and is a relatively recent addition- I've been visiting regularly for about 15 years and I can confirm that it wasn't there during my early visits. It's wonderful that they have been able to create this excellent habitat for the birds to breed. There's a hide overlooking the main scrape, where you can get fantastically close views of the gulls interacting, and honestly it's so fascinating I could watch (and sketch) all day! Black-headed Gulls are so commonly seen scavenging in towns and flying around that it's easy to take them for granted, but breeding season is the most fascinating time to watch any species' behaviour and they are no exception.
 
I visited four times, this year and last year, and saw the colony at 4 different stages.

1. Courtship (21/3/14)

 On this visit I wasn't sure if the colony would be there yet, but it was fully assembled. It's only when I visit this colony that I realise the variety of sounds Black-headed Gulls can make, and most notably, how loud they are capable of being! You can hear them all over the reserve. Most other species that normally live there stay away from the scrape at this time. ^^


The Black-headed gulls were all assembled, but the actual breeding part was only just getting started, and in fact there were a few that didn't quite have their full breeding caps yet (the 'black' cap, actually dark brown, which gives the gull its name). But pairs were definitely forming- everywhere I looked I could see pairs of gulls sitting close together, and one always seemed slightly bigger than the other. When I wrote about the Herring Gulls I mentioned learning that males in that species are bigger than females, and wondered if Black-headed Gulls have this too. It wouldn't normally be possible to tell but having them all sitting in pairs was a useful frame of reference. However the difference may have seemed more pronounced than it really was because the males were showing off so much! They were standing tall, calling all the time with their throats puffed out, and stretching their necks to make the cap look bigger, with the female staying close by their sides.

In one of these pairs, I watched the female start pecking at the male's beak, in exactly the way the Herring Gull chicks from my post above pecked the red spot on their parent's beaks to get them to regurgitate food. Black-headed Gulls don't have pecking spots (their bills are all one colour and dark red), but it seemed to work the same way as the male suddenly regurgitated a couple of lumps of food (even he looked a bit surprised about it! Though that might have been just me XD) for the female to eat. I've seen the female from pairs of birds from other species using similar techniques and it's always fascinated me. Sometimes I think the female is testing the male as a provider by acting like their future chicks will and stimulate his instincts for feeding them, and sometimes I think she is using chick behaviour to get him in the mood for having babies! But most importantly, she needs to be fed to build up her strength for laying the eggs. What was funny with these two was that while the female ate one piece of the food, the male quickly snapped up the other one as if he hadn't meant to give her so much!

This isn't a sketch of the actual regurgitation! It was too quick a moment for that. Just someone poking at pebbles.

But that wasn't all the pairs were doing to bond- they were also displaying for each other! I've watched this colony before, but never this early, so I'd never seen them display before. The gulls would make deep 'bows' to each other, dipping the heads low and raising their behind as high as possible, with the tail fully spread, before coming back up and bending their neck as far as possible upwards so it looked bent round almost at a right angle. It was really strange to watch, not least because the male would sometimes be in the middle of a bow before realising another male was getting too close to his mate, and would suddenly burst out towards the invader to scare him away. It kind of ruined the poise of his display, but needs must!

My attempt at capturing the 'bow'

Another notable thing was the way the birds (particularly, I think, the males) were holding their wings when they were with their mates. Normally a standing gull has its wings tucked flat against its body, but these displaying birds held their wings slightly outwards from the body, in a way that reminded me a little of how male Mute Swans raise the secondaries of their wings up over their backs when they are swimming along. In swans it makes their plumage look particularly fine, and it made the gulls' white and delicate grey feathers look especially smooth and pristine too, but I suspect the actual purpose of this was the same as the swans'- to look bigger and stronger, and threatening to rivals!


Some of the pairs were starting to build nests, but this didn't mean much more than them starting to pick up sticks and bring them to one spot, where one gull (the female?) would be sitting tight as if to 'reserve' it for their use. Gulls aren't great nest builders but I suspect it was still a bit early to see any proper nests. The one in my sketch below kept picking at a plant in front of her that was much too big; there was no way she was pulling it up to get it into the nest but she didn't seem that worried.

Nest building, or just picking at it?

Not all the other birds were elsewhere- there were notable numbers of Oystercatchers on the gull islands too (whether nesting or just hanging around I don't know), and a few ducks, and a nest building Moorhen pair! Their nest was much further along than the gulls', and was nestled in a patch of reeds just above the water level. They were nice and close to the hide so I got a sketch.






2. Nest Building and Incubation (2/5/14)


Flash forward to about a month later, and I visited the colony again to see how their breeding season was going.


It had come a long way! There were nests everywhere, with sitting gulls covering most of the islands on the scrape. Some of the nests near to the hide were even pretty impressive, with large piles of sticks on top of clumps of reed, and incubating birds on each one. None of the near nests had any chicks yet that I could see, though it's possible that some of the nests further away had some.


Sadly the Moorhen's nest was no longer there, and the clump of reeds the pair had been using was now occupied by a gull's nest. Presumably the gulls had muscled the Moorhens away from the spot, and possibly even used the Moorhen's nest as a base for their own nest! I did spot some Moorhens swimming along the side of the scrape though.

I think the nest on the left is the ex-Moorhen nest, now firmly occupied by an incubating gull

The gulls on the reed nests were the most interesting to watch, especially the pair on the right in my above sketch. The bird on it got up to turn her eggs, revealing she had three. However she couldn't seem to relax on the nest and kept getting up and fidgeting with the eggs. I wondered if they were close to hatching and perhaps she could hear peeping or feel movements. But then her mate came back and I began to see why she might be a nervous bird. He kept flying in with new twigs to spruce up the nest (it was big already, but perhaps maintaining the nest shows he is a strong partner), but his mate was filling the whole nest and he couldn't perch next to it without being too low, so he opted for landing on her back! At first she took it quite well, but after a while she began to seem more and more bothered, her feathers got more messy and the male never seemed to be able to find anywhere to put the sticks. After a while she got off the nest altogether and left the eggs for quite a few minutes. I did wonder if they were an inexperienced pair, and whether those eggs would hatch at all at this rate! But it's all experience for next year even if they don't. There might be advantages to an elevated reed nest, but it did seem to present some problems for this pair.


Here's a sketch of some different reed nests. There's a fully made nest on the right, and though I didn't finish drawing it in there's another one on the left. In between them there were a pair of birds who seemed determined to make a nest in the area between, where there was a bridge of reeds. The spot was much closer to the water than two on either side and didn't seem ideal, but they kept bringing sticks and one kept bowing its (her?) breast downwards and pressing it into the reeds as though to flatten them and make it comfortable (that's what's supposed to be happening in the sketch). Either they hadn't been able to bag a space on the islands before they filled up, or the reed nests were actually more desirable and they wanted to create a new spot for one.


I watched a different pair mating, but they seemed to be having a little difficulty! When birds mate (most species, anyway) both of them have to twist their tails around enough for their sexual organs, the cloaca, to touch together. However the male was having so much trouble balancing on her back, flapping his wings around, and waving his tail widely, it didn't seem like they were being very successful!




I thought it would be a bit too late for this kind of thing but I saw on Springwatch a pair of gulls mating right after their nest had been predated by a Badger, so maybe this pair had lost their nest? Or maybe the female just hadn't finished laying her clutch.


All the nest on the scrapes and in the reeds were being fiercely defended, with intruders being chased away with a threatening stance and a fast swim in their direction! Here's my attempt at capturing it:





3. Chicks! (28-05-13)


I didn't visit the colony at the chick stage this year, so now I'm going to confuse you by going back to last year (back when I used softer pencils!). I had an enjoyable visit that yea where I got to see the chicks at their most fluffy and tiny! Gull chicks aren't as cute as, say, wader chicks (though both are the type of chick that is active and downy as soon is it hatches, not the kind that hatch naked and do a lot of growing in the nest), but they have an adorable gawkiness to them that I love trying to capture in my sketches. In my post last year (linked at the top) about the Herring Gulls, and Titan and Wilhelmina the chicks, I spent a lot of time not quite being able to capture the chicks' character, and these predecessors to those sketches had similar problems. But it's all a learning process.


Some of the nests were still at the stage I left them that at last time (or...next year...sorry this post has such a weird timeline!), with birds sitting firmly on eggs and bringing nesting material. I also saw one pair switch which bird was incubating, which was interesting to see. From this I found out that Black-headed Gulls both incubate, which means I was often just guessing about which bird was on the eggs when I talked about them earlier, and noticing roles as clues (like bringing nesting material- is this a way for the male to impress the female?).

It's easy to get behind on your feather care in the hecticness of the breeding season!
This was one member of the pair who switched incubating roles. It had a distinctive brown smudge on the back of its neck below its cap.
The other (assumed male by me at the time) returned at feeding time!


At this stage a few birds, like the one above, were still sitting on eggs, but there were chicks absolutely everywhere! They were speckley brown and fluffy, with legs that seemed too big for their bodies. 



It was raining throughout the visit, but that was ok. When you're in a hide and you're watching nothing but water birds, rain really doesn't effect your birdwatching!
Getting wet = not a problem!

But while the adult birds' feathers were keeping them relatively waterproof, the chicks were all still downy and not waterproof at all, leaving their parents with the job of acting as umbrellas for them. This was done by the parent birds holding their wings out from their bodies as far as they could, and the chicks crowding in as closely as possible. It looked like a tight squeeze! It also looked pretty uncomfortable to have wriggly, pointy-beaked chicks stuffed up under your wings.

Two seemed to be the average number of chicks in each family, or sometimes three, but one family that I made particular notes on stood out.

At first I thought this bird had two chicks, which were both the same size as you'd expect, then another one came and huddled in under her that seemed smaller. Then yet another, smaller still, joined them! I'm assuming they were all hers as it doesn't seem likely that a gull would raise another gull's babies, so maybe there was some form of brood reduction (feeding less to weaker babies and concentrating on the strong ones to ensure they, at least, survive) going on due to her very large family? I then noticed that, sadly, there was a very small, almost dead baby nearby, just outside the nest area. I did think it was dead at first but thought I saw a slight movement; the chicks, jostling to be under their mother, all pecked the baby as they passed it. It was certainly very far gone, anyway. This was possibly the result of brood reduction, for a gull with a clutch of five would certainly be overwhelmed. Or it's of course possible that it wasn't her baby at all, and it just happened to be nearby. Either way, perhaps the chicks pecked because they saw it as a rival in their rush to get a warm spot under their mother's wings.


There were a few older chicks that were bigger, had a few body feathers and were roaming further afield, but they were easily intimidated by the noise and fights constantly going on among the adult gulls. I watched as a couple of these 'teenage' chicks accidentally got in the way of a fight among adults, and to get away from it they left the island they were on and hurried out into the lagoon where it was so deep they seemed to be almost swimming! Perhaps they were swimming- adult gulls swim after all. 


As time goes by in this colony, I've noticed that more and more Common Terns arrive. They don't nest anywhere on the main lagoon, but a few pairs nest in lagoon behind it that seems less popular with the gull colony, and some more are on special tern nesting islands in the lake next to the lagoons (though Oystercatchers and the odd pair of gulls take up a few of the platforms too). Seeing the terns contrasted with the Black-headed Gulls is always fascinating because it makes the terns look tiny. I think of the Black-headed Gull as small because next to Herring and Lesser Black-backed gulls, it really is. But the Common Tern is much smaller again. In fact all the sea terns, even the bigger Sandwich Terns, are smaller than the Black-headed Gull. Then again, I think I checked it out and found that the smallest sea tern we get in Britain (the tiny Little Tern) is bigger than our most numerous marsh tern! (the Black Tern- I did see some once in constrast to Common Terns and they certainly were weeny.)

4. All grown up (15/6/14) (no sketches this visit)

Now in 2014 again, my latest visit to the colony was in mid-June where I was hoping to see more small chicks. There were still some that were downy, but on the closest islands the babies were larger and almost fully covered with feathers, though they didn't yet have the streamlined shape of the adult birds. A Black-headed Gull's first plumage is a mixture of brown and white, mostly brown but with patches of white that make them look very confusing, at just a glance you're not sure what species you're looking at! If they survive until winter, the chicks will moult into a plumage with much more white, with brown fringing across the wings and a dark band at the end of the tail, like the bird in the photo below.

This wasn't taken at Titchfield Haven but was actually from winter 2010, in a park in Paris! I know it's random but it makes good reference for this post. I didn't see much wildlife in Paris so probably there won't be a full post about that. ^^

Black-headed Gulls won't breed their first summer, and gulls you see in spring and summer that look almost like adults, but with some brown fringing and remnants of the black tail band, are probably always one year old. There were a few of these hanging around in the colony this year, and I found myself wondering if any of them were chicks that I sketched back in 2013! Even if not those specific ones, it seemed likely that they were born at Titchfield Haven, and whatever their reason for hanging around there I expect it will help them when they breed to have been around nesting adults when they were younger!


Sadly on this visit I couldn't check on the status of the reed nesting birds (whether the pair had succeeded in making their 'in-between' nest, etc) because the vegetation in front of the hide had grown so high that I couldn't see low down enough. But I did see something rather gratifying: two families of Moorhens! I didn't see either of their nests but one had some medium sized but still downy babies, and the other had three absolutely tiny babies! The tiny chicks were roaming quite far afield but the adults had a close eye on them, and they stuck to the side of the scrape and well away from any of the islands.


There was a large chick on the close island with most of its feathers, but one comical patch of down on the top of its head that it probably didn't realise was there! It was pestering a parent like anything for food, pecking at its beak and trying to get the parent to regurgitate. This succeeded, and the parent dropped a chunk of food onto the ground, but quick as a flash another adult gull suddenly rushed in and grabbed it! Having seen the intruder off indignantly the parent tried again, but it seemed to be having trouble bringing up the next lump of whatever-it-was. Unlike what I've seen with pigeon milk, gulls don't seem to be able to feed their food straight into their chicks' beaks as a liquid, so instead it has to come out in lumps and some of them look hard to cough up! Honestly, it almost painful to watch. :O But the parent eventually succeeded and the baby got its meal, without it being stolen this time.


Speaking of meals, I was viewing from another hide (overlooking the neighboring scrape but you can still see what's going on on the large scrape from a distance), when there was a scuffle on the main scrape- a Lesser Black-backed Gull swooped down and targeted a family of Avocets. (there's a few pairs that breed at Titchfield Haven! It's really cool. They tend to breed further from the hides though so it's harder to observe them.) The parent had at least two large chicks, almost as big as her and mostly black and white but still with grey baby feathers on their backs. She was not happy with the gull's proximity to her babies and shooed it off angrily, with a strangely musical alarm call. I couldn't help thinking that her chicks were probably too full grown to be caught by the Lesser but it was impressive to watch! The Lesser didn't give up however, and swooped over to the gull nests, where despite being hounded by the adult Black-headeds, it managed to catch one of the downy chicks. It quickly bore the chick away to the scrape in front of my hide where there were fewer Black-headeds about, and began pecking at the chick and holding it underwater to kill it. A man in the hide who was a regular there told me it had taken 'dozens' of the chicks. But even if it had, and even if it was quite sad to watch, the Lesser Black-backed Gull had a good reason- living, just like any other bird. Any bird species only has to raise enough chicks every year to replace older birds who have died to keep the population stable, and the colony certainly didn't have as many chicks as it did on my visit in 2013 at this later stage, but it's not like there were incredibly few either! And soon the ones that are still downy will be feathered, and too big for the gull to carry off, and it will have to find a new source of food. The mortality rate of course includes first winter deaths, and then more in first summer and second winter, but the ones who survive into their second summer when they are old enough to breed will have already survived a lot, and they will hopefully be equipped to survive a lot more. The oldest recorded Black-headed Gulls have been in their twenties.




Thanks for sticking with me in this odd travel in time, I hope it made sense! I know I will be watching this colony (and sketching it!) for many years to come. It's not only fascinating, but funny! And now whenever I see those common, town dwelling gulls that are Black-headeds, I think about how much they had to go through to get up, because I've seen it happen. Watching common birds on their breeding sites will ensure you never take them for granted again!



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