Sunday, 11 December 2016
Wednesday, 7 December 2016
This morning, I witnessed my second ever 'great Magpie marriage', one or the most puzzling Magpie behaviours. A group of seven magpies (top shot) were high on a tree, calling, a short call, 'chak!' and bowing with wings half spread, displaying, pecking the branches, or chasing around the tree, but mostly watching each other.
This is a short clip of the gathering.
This behaviour, which usually takes place in the winter, in sunny mornings (although it was quite dark and cloudy today) was traditionally interpreted as the way Magpies form pairs before nest building starts. Tim Birkhead, in an article for British Birds, quotes this passage from Darwin's book 'The Descent of Man':
The common magpie (Corvus pica, Linn,), as I have been informed by the Rev. W. Darwin Fox, used to assemble from all parts of Delamere Forest, in order to celebrate the "great magpie marriage." [...] They then had the habit of assembling very early in the spring at particular spots, where they could be seen in flocks, chattering, sometimes fighting, bustling and flying about the trees. The whole affair was evidently considered by the birds as one of the highest importance. Shortly after the meeting they all separated, and were then observed by Mr. Fox and others to be paired for the season.
Birkhead's research with the Magpie population of Rivelin's Valley in Sheffield showed that instead of a pair formation congregation, this behaviour, is instead a territorial challenge by the dominant non-breeding pair. The rest of the flock attend to witness the event and, although the territory owners often keep their territory, in some cases they are ousted by the dominant non-breeders.
Birkhead, T. R. Studies of West Palearctic birds: Magpie 189. British Birds (1989). 82:583-600. Here.
Birkhead, T.R. 1991. The Magpies. The ecology and behaviour of Black-billed and Yellow-billed Magpies. T&AD Poyser, 270 pp.
Thursday, 17 November 2016
The young gull flies off with the freshwater mussel shell.
Later on, with cloudy weather, two gulls handling the shell.
Wednesday, 16 November 2016
In one of my local parks there is a very high density of Crows. There are several territories, but the park is also the main ranging area of the non-breeding flock (where there is also a winter roost). There are a lot of interactions going on, but without ringed birds, it is hard to make sense of what is actually happening. Yesterday, I observed several interesting interactions. First, a Black-headed gull appeared most annoyed with a Carrion Crow and mobbed it repeatedly, dive-bombing on it when the crow tried to stop on an aerial. The crow did not vocalise and deftly avoided the gull attacks. Later, I heard the rattling call of a crow and watched a chase between two crows, one of them calling with the call I usually associate to mobbing a raptor. Crows, it appears, can use this vocalisation to fend off conspecifics.
Finally, I watched a Crow it an amazing display: its head feathers raised, bill pointing down, looking really at its best. After taking a few photos, I realised it's partner was walking nearby using the same posture. Today I learned about this display in 'The Crows' by Franklin Coombs. It is called the 'Bristle head' display. It is a territory-owner display, used in territory boundaries to signal their occupancy, and also aimed at intruders within the territory. Both members of the pair display while they walk about. There is no vocalisation. Territory intrusions mostly occur during the spring, but there is also a peak in October-November.
I can only presume that this pair of crows are a pair ot territory owning breeders. They do look in great shape!
This is a still from a video, which shows both members of the pair with their 'bristle heads'.
A side view of the displaying crow.
This photo is a bit overexposed, but it shows the details and metallic iridescence of the crow really well.
Wednesday, 9 November 2016
Saturday, 1 October 2016
This is a short clip documenting this behaviour.
Grabenweger, G., Kehrli, P., Schlick‐Steiner, B., Steiner, F., Stolz, M., & Bacher, S. (2005). Predator complex of the horse chestnut leafminer Cameraria ohridella: identification and impact assessment. Journal of Applied Entomology, 129(7), 353-362.
Friday, 26 August 2016
Fucus spiralis, I believe), something I hadn't seen a bird do before.
In subsequent days I watched the visiting woodpigeons, which were keen beachcombers...
...but when a female landed on the beach, a male keenly followed her courting.
As the collared doves, they also ate seaweed, drank seawater (!) and waded in the waves. Don't take my word for it and watch the following clip.
Collared Dove enjoying some seaweed on the sea defences, as they do.
In subsequent days I watched the visiting woodpigeons, which were keen beachcombers...
Saturday, 13 August 2016
Although the Woodpigeon must be one of the most abundant and familiar British birds, a few days ago I was lucky to watch their courtship and mating at very close quarters, when a pair landed on the garden fence. I should have taken a video, but instead I ended taking a series of photos, which don't cover the full sequence. I saw, but did not photograph, the initial courtship feeding.
1. The male (on the right) had just fed the female, both move the bills, like swallowing. They are right next to each other and excited, note the contracted pupil in the male. The female sits down, crouching, inviting copulation.
2. The male mounts the female, balancing with wings open.
3. The male stabilises on top of the female, which remains motionless, with wings spread (to make male balancing easier?).
4. Copulation, male flaps for balance, female leans forward lifting tail.
5. The male jumps onto the left of the photo, both partners (which are extremely alike in colour and size) fluff their neck patch and bow their heads in what looks like an aggressive display. These are woodpigeons in all their splendour, what amazingly beautiful birds they are!
6. The female actually turns away from the male, not a brilliant shot but shows how the neck patch feathers are raised. The pupil is very contracted.
7. The male remains in the post-copulation display.
8. Both pair members come together again and preen (I think the female is now on the right, and shows the initiative in caressing the male neck and head area).
9. The caressing carried on for a while.
Wednesday, 10 August 2016
The adults, although tolerating the young nearby and allowing them to follow and watch what they eat, lunge to them aggressively if they are harassed too much.
Two of the young flanking one of the adults, note the size difference.
The bald adult, possibly the male.
Young are smaller than the adults, with legs that look long for their bodies and wing feathers that are not fully grown. They have a brown sheen to their head feathers and have pink mouths, obvious when they beg. This one has also some wing feather discolouration probably due to some nutritional deficiency.
The young, on the right, begs for food from both adults.
The young crows spend some time away from their parents, walking on the beach, picking seaweed or turning a little stone to peck underneath.
Young crow watching a young Herring gull, from the family they share the beach with.
One of the young crows picked on the empty shell of a spider crab demonstrating its deft foot use (above). Another got a small crab this morning, and a Herring gull chased him. The crow persevered and ate his crab. But as soon as one of the adult crows gets something, the young crowd around.
Thursday, 4 August 2016
A detail of the tower showing the entrances to the nest boxes.
It is quite late in the short Swift breeding season and many fledglings and adults have already left for their African wintering quarters. Every time I see a swift I think it could be the last of the year, so I was not too hopeful of seeing any around the tower.
Birdtrack reporting rate of Swift, showing the main breeding season from May to August.Then the website revealed that the last Swift nestling in the tower was born a couple of weeks ago (18th July) and hadn't yet fledged. The Museum has set up a live webcam in which you can follow one of the nests. The webcam is now set up onto the latest born nestling. I watched the nestling for a while today and got a couple of screen grabs.
An adult likely after feeding the chick, on the foreground, and the well grown nestling. Young have pale-rimmed feathers on their face, unlike adults.
The youngster resting. It spent some time flapping its wings and grooming. Although is quite feathered, its wing feathers are still quite short. The wing feathers will need to reach beyond the end of its tail before it can leave the nest. You can also see a rejected egg just outside the nest.
As we walked onto the square in front of the Museum and just after taking a few photos, a lone Swift flew overhead. Not the mad noisy chases of dozens of Swifts that usually surround the tower at the peak of the breeding season, but a great end of a lovely visit.
Monday, 18 July 2016
Anting is thought to aid in cleaning or disinfecting the bird's plumage. The bird would be using the ants as tools, as ant's secretions, including formic acid have known bactericidal, insecticidal and fungicidal properties. The ants would behave agressively and defensively if they are picked up or rubbed by the bird or if the bird is disturbing their nest.
Blackbirds, other thrushes, starlings and corvids use anting. Some of the species sit on wood ants nests, or even apply individual ants on their plumage. Some bird species use a similar behaviour with millipedes, which also produce strong chemical secretions.
I think it is unlikely anting is a learned behaviour, as it is quite rare. I wonder if the ant's frenzied activity around nests today - it was flying ant day in Hull - stimulated the Blackbird to engage in anting behaviour.
See this post at my other blog on birds and flying ant day
Tuesday, 10 May 2016
Collared Doves have a extraordinary behaviour, their display flight. As males incubate during the day - between 10 am and 4 pm -, and females by night, males are most vocal and active advertising their territory in the early morning and in the evening. Males call their repeated three-note phrase from a prominent perch an aerial or a tree top in the vicinity of their nest. At the end of their call they pause and then launch themselves into a display of pure flight power: climbing almost vertically up to 10 m into the sky, and then gliding down in a broad, long spiral, with wings kept spread pointing downwards, and tail fanned, to finish in the same or nearby spot, sometimes calling a mute trumpet-like landing call. The wing flaps make a soft whistling noise. This sequence can be repeated several times in the early morning and evening. This morning I watched this male sitting on a church top calling, and managed to get the initial jump of the perch into his display flight.redjered here
Monday, 2 May 2016
Goslings seek warmth under their mother's wing. Only females are in charge of brooding the goslings in their first few weeks, when they are still unable to regulate their body temperature.
Despite geese being quite accustomed to people in the park, they still fiercely hiss even as they are being fed. We noticed that pairs differed on how nervous they were. In one of the pairs, the female, instead of hissing, uttered contented calls while she fed and the male didn't hiss at all, despite their goslings being very close to us.
Two families with females brooding young (on the left) and males stand guard.
A group of five goslings follows parents.
Two very nervous parents defending their only young.
Saturday, 30 April 2016
The female feeding.
Note the two aphids on the main veins of the leaf near the male's bill and...
...a few seconds later they are gone.
A short clip of the male feeding.