Wednesday, 13 December 2017

Singing starlings

Starlings sing all year round. True that in spring they spend more time atop vantage points near their nest, throat feathers fluffed, wings fluttering, emphasising their phrases, but even in December they find time to sing. They include calls from other birds, often copied to perfection: pied wagtails, sparrows, swift as some of the ones they have misled me when I realised it was a starling singing. I was tidying up the photos of the year when I found this photo from May, which captures the enthusiasm of a starling singing.

Saturday, 18 November 2017

Ringed Common Gull

The Common Gulls at the local park have been back for a few weeks, slowly building up in numbers to about a hundred today. I searched for ringed ones and found JV47, which I first saw on its first winter in January 2015. It is a fully adult gull now and trusting enough to allow me to take a close up.
Another shot from today.
JV47 as a 1st winter immature in typical chick 'hunchback' posture (23/1/2015). He was ringed  the previous October at Bergen, Norway.
Click here to find out about other ringed common gulls at Pearson Park. If you find a ringed gull and you can read the ring, you can report it to Euring, the European Ringing scheme.

Wednesday, 15 November 2017

Allopreening moorhens

I have only once before seen Moorhens allopreening, and I could not photograph the behaviour. This morning I was luckier. I saw the pair of Moorhens on the other side of the lake in my local park next to each other. One of them adopted the a posture reminiscent to the 'invitation to mate posture', although standing, with head tucked under the chest. The other moorhen then started preening its head and neck, while the first moorhen relaxed the posture. The preening moorhen then adopted the invitation position and the second one briefly preened it. The bouts of preening were not very intense, but directly followed the specific head under chest posture.


This clip shows how the moorhens take quick turns soliciting the preening, and how the preening itself appears rushed and rough at times one pulls the other's feathers.
 

Thursday, 9 November 2017

A story of ringed Mute Swans

Last Wednesday 1st of November I went to Pickering Park. There were six Mute Swans. The resident cob (841 yellow ring), followed by the resident pen (ringed 842, top shot) was busy busking towards a white swan in the lake, who tried to avoid him and ended up preening on the bank at one end. It was a polish variant one, possibly a young of last spring, and when it came out to the shore I could see it was also ringed (red 182Y).
There were also three brown-feathered young swans, starting to moult into adult plumage. Just one of them was ringed (red 537). I assumed they were offspring of the resident pair. One of the brown young kept near the polish one being chased, joining it on the shore.
182Y at Pickering on the 1st of November.
The brown swan accompanying 182Y at Pickering.
The resident pen at Pickering.

***

On Sunday 5th I went to Pearson Park. I was pleasantly surprised to find a mute swan, brown, not ringed. After a while I realised that there was another mute swan, white, on the other side of the pond. The small lake at Pearson Park has very rarely held swans, and not for too long. The last one I saw there was a juvenile from November 2005 to March 2006, when another two appeared in the park before all departed. I casually checked for rings, as I often do, and after some trying I managed to read it. I was surprised to find that the white one was the same that was being chased at Pickering Park, 182Y! The brown young wasn't ringed, but its plumage development is consistent with the one keeping near 182Y at Pickering, so both birds must have left the lake together, possibly an incipient young couple? 
182Y now at Pearson Park. I was able to read the ring as the swan swam.
The brown unringed young at Pearson park.
Both swans at Pearson Park. The white swan showed some aggressiveness towards the brown one, pecking it when it got close.
The swans are getting a lot of attention at Pearson Park. I think the brown one is a male, as it occasionally fluffs up its neck which looks thick in comparison to the other. Still there today, being fed by locals. There is currently a good empty breeding territory at Oak Road lake, it would be good if these two moved there!

Thursday, 13 July 2017

Individual human recognition in crows

Corvid researchers have ample anecdotal evidence that crows recognise individual humans: crows are unusually alert and often direct mobbing calls to researchers that have previously ringed them, while ignoring other researchers. Other crows follow and harass individuals who feed them in order to obtain food, something that Ralph Hancock has described to me in comments to this blog (see previous post), and amply illustrated in his blog (Charley and Melissa are the pair of crows that often pester him for food). Unlike predators, who tend to be dangerous in general, people can be either very dangerous, mildly dangerous, neutral or good to crows. Some people, e.g. farmers who treat them as pests persecute and kill crows (see photo below) and crows might learn to be cautious when they see them and fly away before being shot. Other people are plain annoying, as bird ringers who trap them, and it may pay to learn who they are so that the trap is avoided next time. Yet others people are good to crows, such as people who feed them, and it may pay to be confiding and even harass them to get more food. It is not surprising that intelligent birds like crows pay attention and learn to discriminate between 'good' 'neutral' and 'bad' people and act accordingly.
Two Carrion Crow carcasses on the cows feeder of a local farm.

 John Marzluff, a researcher at the University of Washington has studied crows for many years, and part of his research has involved trapping and ringing crows in Seattle. Marzluff was aware of the crow's mobbing behaviour towards the specific researchers that had trapped and ringed them but he wanted formal proof. He incorporated ringing into an experiment to test if crows recognise individual humans. He worked with American crows, Corvus brachyrhynchos, a close relative of the Carrion Crow with a similar social organisation. The research included urban populations that included previously trapped and ringed individuals, and also 'naive' populations that had not been ringed before. Experiments included a single negative event: the setting a trap (a net launcher) to capture feeding crows in 5 different sites. The people activating the trap, capturing and ringing the birds wore specific masks and/or hats (a 'dangerous' mask). Masks were used so that they were interchangeable and effects due to inadvertent researcher behaviour, outfit or body size could be removed. During transects around the crow territories, researchers (wearing either the dangerous mask or a 'neutral' mask) assessed crow activity towards them before and after the trapping event. They in particular noted if crows displayed the 'scolding' response to them (defined as a harsh, alarm ‘kaw’ directed repeatedly at the observer, and accompanied by agitated wing and tail flicking) or were indifferent. The experiments were repeated by people unaware of the experimental design or objectives, which were asked to walk around the crows territories wearing or not the mask used during the trapping event or a different, neutral masks. This experiment removed any subjective bias by the experimenters themselves.
 The experiments show that crows rapidly learn to recognise the 'dangerous mask' used during the trapping in their local site, with more scolding in response to the dangerous mask than to neutral mask during and after the trapping event, but no differences before the trapping event. In addition, the percentage of local crows scolding the person wearing the dangerous mask increases from 26% steadily with time over 2.7 years to 66%, suggesting that the local crows learn from each other about the dangerous person. The masks used in one of the experiments were of ordinary people and the crows learned to mob the specific mask associated to the trapping and not similar masks.
The crows today calling and wing-flicking.

  Today I walked around the park today with my camera. Three crows at the end of the park, in the same area where they mobbed and followed me three weeks ago immediately flew to the top of a tree and cawed harshly looking in my direction, wing-flicking, then one of them flew towards the tree by which I was standing. I took a video that shows how it is scolding me and records the call. The top shot is a screen gan of the video. As I left the park they stopped cawing. I seem to have become the not so good people to the local crows, maybe I will wear a mask next time.

Cawing 
And flying towards me



More information
Marzluff, J. M., Walls, J., Cornell, H. N., Withey, J. C. and Craig, D. P. Lasting Recognition of Threatening People by Wild American Crows. 699–707 (2009).

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.