Magpie sitting tight

A pair of Magpies built a nest in a maple near our house, as they did last year (that time in the tree opposite). In the the last few days, the tail of the incubating female can be seen sticking out from the side of their large domed nest. Soon, we won't be able to see much as the leaves are growing quickly. Earlier in the year, the magpies were very vocal, now they are surprisingly quiet, if they fledged young, I do not know. The female will take care of incubating while the male feeds her.

This is a photo from 13/03/2015, when nest building was in its early stages.

The female Sparrowhawk and the 'missile' thrushes

There is a breeding pair of Mistle Thrushes in the park. Last week, one was busy finding earthworms on the lawn and carrying them neatly folded in its bill. This means they must be feeding young.  Today I heard the rattling call of annoyed Mistle thrushes. They use this call when they guard their berry trees in the winter, against Blackbirds and even much smaller birds like Chaffinches. The pair of them called and called from a tree. I tried to spot them and saw that a female Sparrowhawk was sitting on a branch. The Mistle Thrushes rattled and swooped over the hawk, the hawk ducked every time they dive-bombed her, although they didn't actually touch her.
 The female Sparrowhawk is an impressive raptor compared to the almost cute, much smaller, male. She is as large as a Woodpigeon, with broad chest and piercing yellow eyes. She can actually bring down Woodpigeons. Although the thrushes appeared fearless, they always stayed over the hawk, not underneath. The hawk moved onto an ash tree nearby, and although higher up, there were fewer leaves in the way, and after some trying I found a clear line of view and managed to take some photos and a video of the 'missile' thrushes dive bombing her. This behaviour, known as 'mobbing' involves potential prey individuals harassing or sometimes actually attacking predators when they are encountered. Mobbing is at its most intense during the breeding season. It is a behaviour that is not completely understood. One explanation, the 'move-along' hypothesis, is that mobbing diverts the predator attention from places where there are nests or young. When the Sparrowhawk's young hatches, they will be fed almost exclusively on fledglings, so harassing the predators might encourage them to move on, and hunt somewhere else.

Mistle thrush with worms in bill (14/4/2015)

The 'missile thrush' was my photo management software autocorrection, but I think it is actually quite fitting! This is an initially very shaky clip (no tree nearby to hold on). Watch out at 11 seconds.

New moorhen chicks

This morning, a moorhen was on the island with three very young chicks. They were tiny and a bit clumsy, and had some trouble following the adult about. There was only one adult with them, so I wonder if its partner is still incubating, or brooding other chicks on their tree nest. These tiny chicks either jumped from their nest, or climbed down the tree unharmed. They peeped and flapped their tiny wings comically, stretching out to their parent, who will occasionally give them tiny morsels of food, one at a time.
 After a while the parent brooded them on the ground, a bit restless trying to get itself comfortable. The following time I saw them, the adult was trying to arrange some nesting material on a branch by the water, maybe not happy with brooding the chicks on the ground? There were a number of large gulls about, and with just one parent around, I wonder what the future of these chicks holds.

Parent finding food.

Chick begging

Brooding time

Coots settling in the park

I wrote about the visiting coot a few posts ago, but there has been new developments in the local park, a few days ago two coots were present and today I counted three coots. They were quite dispersed in and around the pond, but from a particular location all were visible. If they are just coming in or they have been here all along since I saw the first one, I do not know. They are relatively vocal, appearing to keep in touch with each other. This afternoon, two of them seemed quite content, preening close to each other, while surrounded by playing children and lots of people in the park, they most likely dispersed from another park, where they have grown accustomed to people. Male and female Coots have similar appearance, although males are larger and heavier, so possibly the individual in the foreground on the shot above, much larger, is a male. Male and female, however, have very distinct calls. I hope that at least a pair stays in the park as they will provide opportunities to get to watch them closely and learn more about their behaviour.

One of the coots being chased away by the resident Moorhen (with its nest in the island tree).

Coot about to dive

This is the third coot, note its very large frontal shield, protruding from the top of the head and stained pink. The two individuals at the top of the post have much smaller shields.

Forced copulation in mallards

This morning I witnessed a forced gang copulation in mallards. It is a sad thing to watch as the female appears so defenceless, overpowered by a number of males. The female was first pinned down on the ground by three males and a few others joined in later. At least one managed to copulate with her. Forced copulation - as other apparently perplexing behaviours like infanticide - has shifted from being regarded as a pathological behaviour resulting from either captivity, male biased sex ratios or urban bird living, to an sexually selected alternative mating tactic, adaptive for paired males. There are many studies now supporting that forced copulations are more widespread than previously thought amongst some ducks, and are part of their natural behavioural repertoire. (The involvement of many males is probably more likely in urban parks with higher population density than in the wild).
 Mallards form new breeding pairs in the autumn, and the couple stays close together, the male guarding the female. Mating within the pair is very ritualised and brief. There is head pumping by both male and female, the female adopts a flat position and the male mounts her. Here is an example from last week.

 However, occasionally, other males chase a female - often in groups - grasp her and copulate with her forcefully. A feature of this behaviour that made researchers think this might be an adaptive behaviour for males is that forced copulations tend to happen during the period of egg laying, not before egg laying, and rarely after a clutch has been completed. In addition forced copulations tend to happen in the morning, just after the female leaves the nest after laying an egg. The female lays an egg each day, and ovulates just after laying, and it is during this period that there is a small window of time before the albumen is deposited and blocks entrance for sperm that there is a chance for forced copulation to result in fertilisation. The female does not need to be fertilised at this point as she has stored her mate's sperm and therefore she would have fertilised the egg with his sperm. After all, she has chosen this male to be her mate. But the opportunistic males are after fertilising her eggs in this short time window. There is little the female can do to escape the males's attention, she flies away if she can manage, only to be pursued by the males, its male often trying to intervene. I have noticed that males tend to join in chases and forced copulations if they notice a female being chased.

The number of males increased to six at some point. The

 female's bill is just visible towards the right, on the ground.

 Although the female cannot always resist forced copulations, she is not so defenceless after all: her vagina comes to the rescue. What! I hear you say, how? Let me introduce first the fact that ducks are amongst the 3% of bird species that have penises (the right term is pseudopenis or phallus) a corkscrew-like eversible organ, that in the case of the mallard is about 13 cm long (by no means the record, a close relative of the Ruddy duck has the dubious honour).

A screen grab of a male that managed to copulate. Its penis still everted as he walks to the water.

Another view of the male with dangling penis, just after he dismounted.

 Now to the female side. Some female ducks, including the mallard have evolved long, twisted vaginas with dead ends near the cloacal opening, making it harder for a male trying to copulate with her to achieve a successful intromission and fertilise her eggs if she doesn't collaborate. The female's vagina also twists clockwise, making it harder for the male anticlockwise rotating penis to work. The males of these duck species also have longer penises. This co-evolution might have been spurred by forced copulations, in which the females respond to increased penis length with increased vaginal complexity to thwart the likelihood of successful fertilisation. The little data on extra-pair paternity in ducks appears to support this hypothesis, as the occurrence of extra-pair offsprign appears to be quite low (less than 10%) in the ducks studied. An excellent example of an arms race between the sexes.

More information

Brennan, P. L., Prum, R. O., McCracken, K. G., Sorenson, M. D., Wilson, R. E., & Birkhead, T. R. (2007). Coevolution of male and female genital morphology in waterfowl. PLoS one, 2(5), e418.

Cheng, K. M., Burns, J. T., & McKINNEY, F. R. A. N. K. (1982). Forced copulation in captive mallards (Anas platyrhynchos): II. Temporal factors.Animal Behaviour, 30(3), 695-699.

McCracken, K. G., Wilson, R. E., McCracken, P. J., &; Johnson, K. P. (2001). Are ducks impressed by drakes' display?. Nature, 413(6852), 128. here.

The very angry Moorhen

The lake in my local park is now divided up in two Moorhen territories. One pair has the island - now with a nest high in a willow well under construction, possibly already with eggs, the other has the opposite end of the pond, a more disturbed area which only has two patches of marginal vegetation near a path as potential nesting site. One of the island Moorhens climbed the willow tree with some nest material and passed it delicately to its partner sitting on the nest. Both males and females carry out nest building and are virtually indistinguishable by plumage, although males are a bit larger. After a while I saw the moorhen approaching some vegetable refuse that some passer by had dumped on the grass. The moorhen then spied either the other territory owner which was about 5 m away, or the coot that was standing nearby, and carried out the most wonderful display. With the bill quite low and the tail as high as she could keep it, it erected its white tail feathers, and half opened its wings, strutting while showing its bottom to the rival moorhen (which appeared quite indifferent). The view of the rival moorhen approaches the photo at the top. And the front and side views of the displaying moorhen are below.

 You can watch a clip of the behaviour here.



You can also watch the moorhen strutting to a potential predator, a stoat, which I filmed recently here.

Snooze time for a Greylag pair

The large wintering Greylag flock in my local park has now disintegrated into pairs, which have moved onto their breeding areas. The last few times the flock was around there were many fights as males started to become very aggressive towards other males. There are now just up to three pairs remaining, sometimes just the one. Yesterday, they were resting with the resident Canada Pair in the lake island where they are less disturbed by dogs and people.
 This pair, is easily recognisable by the male's black bill tip. In ducks, swans and geese the thickened tip of the bill is called a nail. In grey geese, juveniles have a dark nail, while in adults the nail is pale (so I have named this unusual male Black Nail). They are illustrating that paired geese tend to stay close together and do the same things at the same time: rest together, travel together, feed together. Research on the semi-tame Greylag flock established by Konrad Lorenz in Austria, showed that bonded pairs also carry out complementary behaviours, for example males are vigilant while females are foraging or resting. Pairs that had successfully reared offspring together differed from unsuccessful pairs in that they showed more reciprocation: females are vigilant when male feeds more often than in unsuccessful pairs.
  Unlike corvids or parrots, in which mutual grooming is important to keep the pair bond, geese never groom each other, in fact, I don't think I have even seen a pair of geese in actual physical contact (e.g. roosting against each other like pigeons or crows do). Instead, they are social allies, they rely on each other's support against rivals or intruders, and carrying out ritualised triumph ceremonies afterwards. In the Konrad Lorenz flock, although successful and unsuccessful pairs had a similar within-pair distances (keeping within one meter of each other), when previously successful pairs failed a breeding attempt, they remained closer together, showing a tighter social bond.

Eyes open

Eyes half close

In this video you can see an aggressive male chasing away other geese in the flock (taken 27th February 2015).



More information
Scheiber, I. B., Kotrschal, K., Hemetsberger, J., & Weiß, B. M. (Eds.). (2013). The Social Life of Greylag Geese. Cambridge University Press.