Standing pretty

In the low winter sun, this magpie was tree-topping, displaying her contrasting black and white plumage, a typical territory-owner behaviour. They will 'tree-top' on aerials and buildings alike in towns. This one also regularly 'tail-flirted': a quick bow and tail flick, which is very noticeable and draws attention. Magpie's apparently black plumage has structural iridescent colours, blue sheen in the wings and green and purple in the tail tip - as shown in this tail feather - which are shown during displays and aggressive encounters. Breeding, territory-owner magpies have the brighter and greener iridescent hues than non-breeders. Plumage brightness in birds especially in body parts that are displayed during territory defence or during fights, reflects the owner's health and attractiveness, so their display advertises not only territory ownership, but its good body condition, so that potential challengers can assess it, and potentially avoid fights that they might be likely to lose.

On Magpie marriages

As in other corvids, like Ravens and Carrion Crows, non-breeding magpies flock together. The non-breeders tend to be young birds, while territory holders, which breed, are more likely to be older. There is a hierarchy in the flock, and the dominant birds are more likely to be the next in line in obtaining a territory. Magpies form pairs in the non-breeding flock.
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.

My first Magpie marriage, on a sunny morning a few years back (9/11/09). Individuals fluffed their white feathers in their displays.

More information

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.

Playing herring gulls

This morning at a local park, I noticed a young Herring Gull picking an object, flying off and being chased by another. Then the gull landed on the water and dropped the object and pretended to dive to pick it up repeatedly, as in a lazy drop-catch game. When I saw the object at a better angle I realised it was an empty freshwater mussel shell, which happened to float. Funnily enough, a couple of hours later when I walked past either another or the same young Herring Gull was still playing with it.

The young gull flies off with the freshwater mussel shell.

Later on, with cloudy weather, two gulls handling the shell.

The bristle head crows

Carrion Crows have a complex social structure. Territory-owning Carrion Crows remain paired year round, often flying and feeding together or not far from one another. They remain near their nest during the breeding season, although they may range wider outside this period. Birds that don't hold a territory form part of a loose flock that roosts communally, usually in large trees. Both male and female of a pair participate in territory defence, keeping other crows (or potential predators) away from the nest. Males have a more prominent role: if a male loses his mate he is able to defend the territory until he remates, but a female losing his mate will also lose her territory, as she would rapidly be evicted by other pair.
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.

Chok, chock, chock!

I've been wanting to take a photo of a Blackbird in this posture for a long time. Blackbirds do often cock their tails. When they alight they do that tail-cocking so as to keep their balance - in a similar way to Woodpigeons - they often do a jerky tail-cocking action when they do one of their various alarm calls 'chok, chok, chok' at the same time than they flap their wings. On Sunday, a windy day, this Blackbird perched on the side of a drinking trough, the wind made it lose its balance a bit and it stayed, tail cocked, for that second longer for me to press the shutter. Got you!

Great tits feeding on horse-chestnut leaf miner

In a walk around the local park, a pair of Great Tits called my attention. They were calling and foraging in a horse chestnut. I watched how dexterously they grabbed the large leaves with their bills, pulled them towards them, and held them with one foot while feeding (top shot). They were looking for larvae or pupae of the horse chestnut leaf miner, Cameraria ohridella, a micromoth that has expanded its range throughout Europe from its native Balkans. The moth's larvae feed inside the leaves of the horse chestnut, leaving them speckled. Blue tits also feed on this leaf-miner (as do Marsh Tits), and I've seen them feeding on them before, but as they are lighter than Great Tits, they are able to just hang from the leaves themselves.

A short clip demonstrating this behaviour.

More information
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.

Beach pigeons

In my recent holidays, it wasn't only the local Carrion Crows that visited the beach at low tide, Woodpigeons and Collared Doves regularly popped in. The first day I noticed a Collared dove on the sea defences pecking on something, when I looked closer I realised it was eating seaweed (Fucus spiralis, I believe), something I hadn't seen a bird do before.

Collared Dove enjoying some seaweed on the sea defences, as they do.

I took a video the following day.


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.