A pair of bullfinches

Bullfinches are generally shy and unobtrusive, they tend to stay hidden in vegetation and show little. It helps to recognise their sad contact note. I see them around regularly enough, but good views are rare. That's why I got quite excited that a pair of Bullfinches, Pyrrhula pyrrhula, recently started to frequent the local wildlife garden, giving me an opportunity to become more familiar with their behaviour. I first noticed a female, funnily enough at the Big Garden Birdwatch. I heard a specially mournful version of their call, possibly she had lost track of her mate.

The hard to photograph female amongst the bushes

The next day, both were around, skulking in the trees and hedges, occasionally coming to the ground to feed. They stayed close to each other, but still called regularly. They appeared to be feeding on buds and Guelder Rose berries.

The male feeding on Guelder Rose seeds

Yesterday, the pair was about, feeding together on Sycamore seeds, the last remaining ones on a tree, and had to stretch and balance precariously on the branches to get at them. Despite their stockiness, they are quite nimble. They peeled the seeds using only their parrot-like bills, unlike goldfinches that have to hold the seed with their feet.

 Bullfinches will feed on buds in spring. In autumn they feed on tree seeds, like Ash keys, Birch and Sycamore. Bullfinches are seed predators of berry producing trees: they discard the flesh of the berry and feed on the seed itself.

Woodpigeon fledgling chasing parent for food

I saw a young woodpigeon fledgling by the pond today, it shook its wings occasionally like young to when they demand food and I noticed an adult was nearby. The young one caught up the the parent and touched its bill, to which the adult responded by regurgitating food. The young continued chasing the adult for quite some time, regularly managing to be fed. The size different between both is quite noticeable in the top shot. 

 Young woodpigeons are much drabber, greyer than adults, without a pinkish tinge. Legs and bill also lack the red and orange hues of the adult, and the bill does not have a developed cere or operculum, the swollen covering covering the base of the bill. Young woodpigeons have dark eyes and lack the parents neck markings. Although their smaller size and black eyes makes them similar to a Stock dove, they still have the trademark white woodpigeon wing-bar.

A side view of the fledgling

I also took a video of the sequence. 

Summer and winter Blackcaps and evolution

During April, Blackcaps return to thickets and woodland, where the male's beautiful song joins the resident birds. These Blackcaps have just arrived from their winter quarters in Spain and North and coastal West Africa. We tend to think of migration behaviour as something fixed, but recent research shows that many birds have recently changed their migration routes. One of these is the Blackcap.
In the last 50 years or so, a small contingent of Blackcaps have started to winter in the UK. About 30% of gardens have a wintering Blackcap in recent years. Is it because these birds are staying here year round? Surprisingly not, they are migrants from the continent, mostly from Germany, where they breed. This migration behaviour has evolved in a few generations, with these birds taking advantage of milder winters, increased food availability in gardens and a shorter migration route. They usually migrate to Britain and Ireland as winter berry and winter temperatures drop at the beginning of the year. The direction in which blackcaps prefer to migrate is innate, strongly influenced by one or a few genes: the offspring of blackcaps migrating NW prefers to migrate NW, and the offspring of hybrids between NW and SE migrants have an intermediate migratory direction. Birds with both migration strategies coexist in South Germany and Austria. The different migration routes mean that they arrive at their breeding grounds at different times, and therefore tend to pair with birds with a matching migration strategy. The birds involved in the shorter Germany-UK migration trips have evolved shorter, more rounded wings than the Mediterranean migrants. In addition, they have slightly different plumage colour, with might also help them find the right mate. Bill shape is also different, possibly reflecting a different diet: birds wintering in the Mediterranean feed mostly on fruit, while British wintering birds rely mostly on fat and seeds in gardens. These differences are reflected in incipient genetic differentiation between blackcaps with different migration routes present in the same area during the breeding season, which could mean that both populations eventually become different species.

A wintering female Blackcap feeding in my garden. 26/1/2013.

A summer migrant male singing today.

More information

Rolshausen, G., Segelbacher, G., Hobson, K., and Schaefer, H. (2009). Contemporary Evolution of Reproductive Isolation and Phenotypic Divergence in Sympatry along a Migratory Divide Current Biology, 19 (24), 2097-2101 DOI: 10.1016/j.cub.2009.10.061
Fiedler, W. (2003). Recent changes in migratory behaviour of birds: A compilation of field observations and ringing data Avian migration, Springer Berlin Heidelberg., 21-38 DOI: 10.1007/978-3-662-05957-9_2

Bottoms up!

This is probably one of the most familiar duck behaviours. Mallards often 'upend' to feed, submerging the anterior parts of their bodies and keeping their tails pointing up, while keeping their balance paddling with their feet -  a behaviour most kids find hilarious. Although it is not a universal duck feeding method, Mallards are amongst the experts. Mallards are dabbling ducks, they obtain most of their food from near the surface. Upending allows them to reach just a little bit deeper and feed at depths not used by smaller dabbling ducks but too shallow for diving ducks. In contrast to smaller dabbling ducks, mallards and other large dabbling ducks can afford to upend as their large size allows them to reach deeper and to remain submerged for longer.

Proportion of Mallards feeding using different feeding methods (from Green, 1998).

In a comparative study of duck feeding behaviour, Andy Green found out that neck dipping and upending were the predominant feeding methods in Mallards. Ferruginous ducks, a species of diving duck, did not upend and barely used the neck dip, diving was overwhelmingly the most commonly used method. 

 You can watch Mallards upending in this short video:

More information

Andy J. Green (1998). Comparative feeding behaviour and niche organisation in a Mediterranean duck community Canadian Journal of Zoology, 76, 500-507 : 10.1139/z97-221

The Common Pochard

Common Pochards, Aythya ferina, are common wintering ducks in the UK. I find intriguing that most of the birds in my local park are males. However, this is the case for the whole UK winter population, with males outnumbering females in a 2:1 ratio. In sites where supplementary food is given this biased sex ratio can be much more extreme (5:1). Females appear to migrate further south than males, and the reason for this could be that males are much more aggressive towards females than they are to other males. Confronted with this intraspecific competition, females move on to areas where there are fewer males. Males might benefit from shorter migration distances by coming back earlier than females to establish breeding territories.

  Pochards, unlike other birds, seem to have the same pattern of activity between day and night, they are cathemeral. Bouts of feeding are followed by bouts of sleeping day and night, and they are often found resting in flocks during the day (they still sleep about 50% of the time).

  In the winter, these diving ducks feed mostly on seeds and fuiting bodies of aquatic plants (Chara, Nitella, and Potamogeton being a large fraction of their diet). Their distribution is limited by their diet, as they require large bodies of water with good population of aquatic plants. They feed by diving and up-ending, and, they probably rely on the sense of touch to feed, which may explain they do not need light to feed.

One of the few photos I have got of a female Pochard, in the company of Tufted ducks.