Monday, 19 June 2017

Mobbed by crows

In my way to work as I crossed the park I saw a pair of crows with a fledgling. The young one hopped to one adult and was fed. I took my camera out and started taking photos, but all feeding and begging stopped. The young one started looking around for tidbits on the grass. One of the adults, after eyeing me (the one in the background above), flew to the top of the tree under which I was standing, and cawed loudly and repeatedly. The other adult followed. I didn't think much about this until I carried on with my walk and the crows flew from tree to tree above me, calling all the way, sounding pretty angry. It took that for me to realise that I was being mobbed! I thought about the episode by Konrad Lorenz when his tame jackdaws apparently mistook his wet swimming trucks, which he was holding, by a dead jackdaw and actually attacked his hand, drawing blood. I saw my black camera with dangling cap and immediately put it away. I do hope the crows don't remember me tomorrow!
 Curiously, but not surprisingly, this call is completely different to the mobbing call uttered when chasing sparrowhawks or gulls away (the call that gave name to this blog), which is a dry rattling. Instead is a long, harsh caw. I found a video of a crow attacking a fox and using the same call.
The adult, on the right, eyeing me. 
The young crow stops feeding, as the adults caw above me. 
The young crow is taking everything in, looking at the parents reaction.

Thursday, 15 June 2017

Stock dove driving

Stock Doves are so intriguing. A combination of shyness and a superficial resemblance to feral pigeons makes them often pass unnoticed. Several times this spring I have watched them in flight, usually a pair, sometimes trios, with one of the doves flying right above another, their wings almost touching, but there didn't seem to be aggression in the behaviour. What are they doing?
 I might have found the answer today, reading an old article by Derek Goodwin. He describes a behaviour called 'driving' which is present in several members of the pigeon family, including the domestic pigeon. This is his description:
The driving cock follows his mate everywhere, often literally "treading on her tail". He pecks, usually in a gentle manner, but sometimes fiercely, at her head. If the hen takes wing he flies closely behind and above her. If she goes to the nest (domestic birds) the male stops driving.
Pigeon breeders thought that driving meant that the male pigeon wanted the female to go to nest, given that when the female goes to the nest the driving stops. Goodwin disagreed with this interpretation and thought instead that driving allowed the male to keep the female away from suitors, either on the ground or in flight.

In the two photos illustrating this post, a third pigeon was flying out of frame. I presume the male is the individual above, intercepting the female from the male.

Goodwin observations were consistent with this, as driving happened when other males were near the female, in particular during a period before egg laying and ended once the first egg has been laid, that is, a period when the female is sexually receptive, so that the behaviour is the way the male keeps the female away of competitors, and is effectively a form of mate guarding, as he put it 'It functions to prevent insemination of the female by males other than her own mate. Interference with copulating pairs is part of the same behaviour-complex as driving and has a like causation and function.' When, occasionally, driving was observed with just the pair involved, he thought that the male had succeeded in his driving: 
I have seen a pair fly up from some crowded feeding ground, and the male, who was at first driving hard in flight, swing out beside or in front of his mate as they got well away from others in the air, usually going into display flight as he did so.
More information
Derek Goodwin (1956) The Significance of Some Behaviour Patterns ofPigeons, Bird Study, 3:1, 25-37, DOI: 10.1080/00063655609475836.

Stock dove take over

Yesterday the insistent, zebra-like call of a stock dove just outside the house called my attention. It was atop the Tawny Owl box. We've got the box occupied by the owls since the beginning of the spring, and I presume that they fledged their young earlier as they have been quiet in the last couple of weeks. It's funny that the owls took over the repaired box from Stock Doves and now the doves are back. He was there just now, calling again. The doves should have enough time to raise at least a couple of clutches.

Wednesday, 14 June 2017

Carrion crow fledgling

The Carrion Crow pair in the local park have fledged two young. One of them sat on a carpet of poplar fluff, looking sleepy, and unable to fly very high. It looked like it had flown the nest a bit early. It was very tame, and allowed me to crouch by it and take his portrait. You can see that the chest and head feathers lack the metallic lustre of the adult plumage and the young's eyes are blue. The wing feathers are more metallic. A parent was nearby, furiously chasing a squirrel away. The sibling was much more active, and was intrigued by water, it opened it's bill to the water, like it was testing it or finding out what the best way of drinking was.
The inquisitive sibling.