A flock of local Lesser Redpolls

The coldest morning of the year so far, I take a walk around my patch. Lesser Redpolls are a rare winter visitor in the city, and it's hard to predict where to find them but my local patch has been quite reliable every year and cold weather pushes them south. Today I encountered a small flock quietly feeding on catkins in some small birches in the cemetery. There were at least five, one of them, a male. They allowed me to approach and watch them hanging from the thinnest branches, holding a birch catkin against the branch with a foot while feeding from it so that they can extract the seeds more efficiently.

Adult male Lesser Redpoll.

Here you can see how they hold catkins while they feed.

A female/immature feeding.

A view of the flock. From a distance, very hard to see!

They kept feeding, until a sudden Blackbird alarm flushed them all but one. The lone individual called, and left flying towards the flock.

Rooks hoarding acorns

It is a mast year, with a bumper crop of acorns across the city. October is peak acorn season and last week I saw the first Rooks carrying acorns. Acorns are packed with energy, and several bird species take advantage of them. Woodpigeons, presumably swallow them whole from the trees, but Rooks and Jays collect the harvest and store it for use during the winter. Both species are scatter hoarders, and cache individual acorns on the ground, and use their extraordinary spatial memory to recover them later in the year, when other food resources are scarce. Although the Jays are best known for this behaviour, Rooks are also amazing acorn hoarders. Rooks can transport acorns - and other food items - in a pouch under their tongue, which obviously bulges as they fly over with their pouch full. The number of acorns they can carry depends on the acorn size, and varies from 2 to 7. They prefer to cache the acorns on grass, and can fly up to 4 km from oaks to suitable grassland. Once they find a good spot, they drop all the acorns they are carrying and bury each one by one, by first making a hole in the ground with their bills, and then hammering the acorn in and covering it with grass, leaves or soil. Later on, they will visit the caching sites in the winter, find their stored acorns and crack them open to feed. 

A vocal Rook on an oak canopy, surrounded by plenty of acorns.

Rooks, unlike Jays, are very social and engage in communal acorn collecting, becoming very vocal when landing on the oaks canopy. They prefer to gather acorns with other Rooks, and individuals appear to join other individuals gathering acorns by flying in the opposite direction of individuals with full bills. When it comes to caching though, Rooks prefer to be alone, to avoid cleptoparasism, when other individuals try and steal their stored acorns.

Rooks displaying, the individual on the right, with distended sublingual pouch, passed an acorn to one on the left, presumably they are a mated pair.

More information

Waite, D. R. K. Food caching and recovery by farmland corvids. Bird Study 32, 45–49 (1985)

Källander, H., 2007. Food hoarding and use of stored food by rooks Corvus frugilegus. Bird Study, 54(2), pp.192-198.

Siskins Galore

 

There is something about birdwatching that I find so rewarding: learning a simple thing, like a species contact call, opens a new world. Although they are regular wintering birds, I don't think Siskins are becoming more common around Hull. It is just that once I learned the beautiful soft, sad 'pew! call, then I am seeing them everywhere, and this year I have really enjoyed watching Siskins. 

Siskin feeding on Italian Alder this afternoon.

In the depths of the winter, when days are gloomy and cold, Siskin flocks rove around the city looking for Alders. They feed on both Common and Italian Alders, clinging from the cones sometimes upside down, deftly extracting seeds with their pointy bills. In quiet areas they might come down and feed on seeds on the ground.

In the last few weeks, the chattering singing chorus of Siskins have alerted me to flocks feeding in Lombardy Poplars in three different locations around the city, possibly as the seeds in Alders are becoming depleted. I was intrigued as I thought these catkins were pollen catkins. Lombardy Poplars are male clones, which produce red pollen catkins. Being wind pollinated I didn't think they had nectar (which would be odd for a finch to eat anyway), but I've never heard of a bird feeding on pollen. What are they feeding on then? Insects, possibly aphids, is a possibility, but it appears unlikely so early in the year.

Male Siskin feeding on Lombardy poplar catkins.

So, a bit like the Goldfinches feeding on lichen covered branches, I don't have an answer to what Siskins are feeding on, but Lombardy Poplars are plentiful around the city parks and playing fields, where they are planted as wind breakers, so hopefully they will stay around a little longer.

Please do let me know in the comments if you know the answer to the mystery!

Waxwing gift passing display

 After a long hiatus, I came across some Waxwings today. Six individuals were perched high up on a Lime tree, taking the sun in. They were quite active, changing branches, pecking the shiny, red tree buds. Two in particular called my attention, as they approached each other touching bills, then coming apart. I took plenty of photos, some unfocused by branches getting in the way, but, looking at them in more detail back at home, I noticed that the two individuals 'billing' were doing more than that, they were exchanging an object, probably one of the tree buds, in a ritual display called 'gift passing' (top shot). The behaviour is seen both in the Bohemian Waxwing, which we get in irruption years in the UK, and in the American Cedar Waxwing. 

The behaviour consist on passing an object, then the individual with the object jumps away, then joins its mate, which 'receives' the object, then the behaviour is repeated and the object passed backwards and forwards repeatedly.

The individual on the left has the gift now.

The individual on the right has it now. Note the raised crests.

Here a Waxwing shows interest in the bright red, shiny buds of the lime tree.

And here, another individual holds some buds in its bill.

I found a description of the behaviour, based on captive individuals and illustrated with photos, which shows that the display is also accompanied from fluffed rump and belly feathers, raised crest and lowered tail, the latest something not very obvious in my photos. The male appears to initiate the behaviour, obtaining the object, and sidling to the female, presenting it. If successful she will accept the object and reciprocate, after jumping away, then close. It is difficult to sex Waxwings, males apparently have longer crests and a more clearly delimited black chin patch.

This is a clip of the behaviour in the Cedar Waxwing, there seems to be a lack of recordings for the Bohemian Waxwing, although the description and my observations fits both species sharing this wonderful display.

More Information

Meaden, F. M. & Harrison, C. J. O. Courtship display in the Waxwing. British Birds 58, 206–208 (1965)