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. Even in December though, they find time to sing. They include calls from other birds, often copied to perfection: pied wagtails, sparrows, swift are some that 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.

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.

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.
 

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!

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).

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.

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.

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. 

Encounters of the Sparrowhawk kind

I treasure encounters with Sparrowhawks as they are quite secretive and alert birds which don't like being seen. Today I managed some sightings of a pair in my local park. First I heard a call 'kikikikiki!' and I saw a female landing on a tree. The view was quite obstructed and unfortunately, she flew off as I tried to get a better view. 

Then, a while later, in the same area I spotted the male. Not sure how, possibly a blue tit alarm call alerted me. He had some prey, what looked like a small bird, and was plucking it.

 He flew off, carrying the prey in his talons, and I wandered after him towards some big trees where he had disappeared. Then I saw the pair together, high up the crown of one of the largest trees in the park, a poplar (top shot). Fortunately the beautiful light made up for the distance to take some photos. The male started preening. I couldn't see if the female had the prey now. Male Sparrowhawks hunt for the female while she incubates.

The male at the top, smaller and with reddish tones in his plumage. The female at the bottom, all alert. Soon tree foliage will completely obscure views of these birds from the ground.

 On my way back from work I looked longingly at the poplar. No Sparrowhawks to be seen there. But then, beyond the tree, high in the sky, the pair was circling together, playfully chasing and soaring.

Blackbird mob

Returning home in the light evening today I noticed Blackbirds 'chinking'. This is a very persistent call, often by several individuals, that I usually associate to summer evenings. The blackbirds, up to four of them, were in the tree where the Tawny Owl nest box is. The owls are indeed in occupation, although they were nowhere to be seen from the ground. They have been calling at dusk, and every few days I have been able to watch one of them as it called, sat on the box for a few minutes and then left to go hunting. Often, later at night, one calls with a lovely gurgling sound from inside the nest. Two of the blackbirds got close to the entrance, calling non stop, if there was an owl in the nest, they might be able to see it. At some point they calmed and left, but then one returned, started calling and the others joined him in the tree.
I wondered that the 'chinking' is not a roosting call, but a mobbing call to an owl, which is more likely to be encountered active as nights become lighter in the summertime. In a couple of weeks, the leaves would obscure the view and although a blackbird calling is evident, a quiet owl sitting inside a tree is not. This is a lovely clip of blackbirds mobbing a Tawny Owl demonstrating the call and also how fearless they are towards the owl.

UPDATE 7 April 2017. From the living room at 20:05, I heard a Blackbird suddenly starting to 'chink' and I looked at the nest box. The round silhouette of a Tawny was sitting atop the nest. It was light enough to get a low resolution photo.

Woodpigeons calls and displays

Although the woodpigeon is the bird I come across most often and the one I record the most, it is still one of my favourite birds, the species that made me a birdwatcher. I find them truly stunning and very resourceful, feeling at ease in gardens, parks and woodland alike. Despite their reputation as grain guzzlers their diet includes leaves, nuts (acorns and beech mast), buds, flowers and berries, including rowan, ivy, holly, cotoneaster and alder, which they often reach with great acrobatics. Although Woodpigeons have featured often in this blog, here I am compiling and documenting their calls and displays, especially those related to reproductive behaviour. Although in his article on woodpigeon behaviour Cramp says that 'they mark their ownership of a territory primarily by just being there' as indeed 'a Woodpigeon perched in a tree bare of leaves is a large and conspicuous object' Woodpigeons have a simple, but interesting behavioural repertoire.

Advertisement call. A deep, repeated 5 note phrase that serves as a territorial song. This is the well know Woodpigeon song, often heard early in the morning.

Display flight. This is another territorial display most frequent in February and March. The male flies around the territory rising in a broad arc, and then gliding down with wings held stiffly horizontal advertising ownership. They can do the rising and falling a few times before alighting. Although mainly a visual advertising display, as the bird does not call, sometimes the bird will make a clapping noise with its wings at the apex of the arc.

The Bow display. It is a courtship display that territorial males perform when still unpaired and trying to attract a mate and also when the pair bond is becoming cemented. The male approaches the female and with his neck enlarged he calls a three note call as he alternatively stretches up and then lowers its head, displaying the white and iridescent neck markings, and fanning the tail when it's at its highest. Check out this wonderful photo by Richard Hawley showing the display when fanning is at its maximum. Females can display some aggressiveness to the courting male, move away or flee if they are not interested. This display often happens on trees, roofs or aerials, but occasionally on the ground. When on the ground the male will try and get closer and follow the female hopping to bow just in front of her, one of the few occasions that woodpigeons will hop instead of walking.

Allopreening, billing and mating. Feeding the mate, gentle preening and billing precedes mating. I documented this behaviour in a series of photos here.

Slightly opened wings is a threat posture.

Fighting. Woodpigeons have large chest muscles, which power their explosive take off and fast flight. They have small bills and legs, so they also use their wings as offensive weapons in their territorial fights. Males will fly towards intruders landing in their territory and land adopting an aggressive stance, with neck stretched, flattened plumage and semi-open wings, and often this is enough to drive the intruder away. Occasionally, this develops into a fight, which sometimes occur in the depths of a tree. The pigeons will land near each other, alight their bodies and flap trying to hit each other (above).      
                                         
Nest calling. This is a call by the male signalling to his partner a suitable nest site. I've covered this on other posts (here and here) and it is described in detail in the article by Cramp cited below. The call is harsh, and guttural composed of two notes, here is a recording of the call. I want to share here a video I took this morning, in which I got a good angle. You can see pecking or nodding movements to the nest floor in between calls:




More information
Cramp, S. Territorial and other Behaviour of the Woodpigeon. Bird Study 5, 55–66 (1958). here.

A drop-catch game sequence

A caught a short clip of a young Herring Gull playing drop-catch today at a local nature reserve. The gull carried on for quite a while dropping and catching the item.

via GIPHY

Moorhens mating

This week the local pair of Moorhens have been mating. Females in Moorhens and Coots, and presumably other rails, have a curious way of inviting their partners to mate: They bury their heads down into their chests.

Carrion crows dropping mussels

Today at Sewerby beach I was intrigued by a Carrion Crow, part of a large winter flock, appeared to drop something onto the rocks at the top of the beach, then come down to eat. Sometimes the crow would fail and repeat the action. The tide was low, exposing a flat platform of rocks with rich mussel beds, and the objects being dropped were actually mussels that the crows were collecting and carrying up the beach before dropping them on the solid rock to smash them (above).
Dropping potential food items to break them open has been previously documented, and best known in Golden Eagles (breaking open tortoises) and Lammergeiers (bones). Gulls and crows of various species have been recorded dropping intertidal hard-shelled molluscs hard substates, including roads. Intertidal foraging can be an important part of the diet of coastal crows in the winter, when insects are scarce. Crows will scavenge at the tide-line, or feed on small crabs, but some of these intertidal organisms, in particular periwinkles, cockles and mussels, are consumed after smashing them open by dropping onto hard substrates. Controlled observations of wild Carrion and Hooded crows show that crows chose larger mussels, more likely to smash and also providing more food. Shell dropping is not instinctive, young crows appear to perform rather poorly. They need to perfect their technique of dropping so that the height at which the mussels are dropped is the minimum height for them to break at impact, but not much lower. Young crows take more attempts at being successful.
There are three reasons why the minimum height should be used. One, dropping from higher up means wasting more energy flapping up. Also, higher drops means higher bounces and higher chances of the shell being lost. Finally, crows and gulls often steal from each other, a behaviour called kleptoparasitism.  Therefore researchers predicted that crows dropping mussels when other crows or gulls are nearby would be more wary of being robbed, indeed, crows with other crows or gulls nearby dropped their mussels from 2 m lower that lone crows.

Crow and gulls on mussel bed, the crow has already detached a mussel, while one of the gulls is still trying. Although many crows were actually busy either collecting mussels or breaking them up the beach today, I didn't see any gulls doing this.

Mussels are strongly attached to the rock and other mussels by threads, which can be hard to reach, as the mussels cover the rock very densely, not exposing the threads. It is quite a feat the crows manage to detach them

A view of the beach at low tide.

Despite the very bright light I managed a couple of clips here:

More information

Whiteley, J. D., Pritchard, J. S. & Slater, P. J. B. Strategies of mussel dropping by Carrion Crows Corvus c. corone. Bird Study 37, 12–17 (1990).

Davenport, J., O’Callaghan, M. J. A., Davenport, J. L. & Kelly, T. C. Mussel dropping by Carrion and Hooded crows: biomechanical and energetic considerations. J. Field Ornithol. 85, 196–205 (2014).

Berrow, S. D. , T. C. Kelly & A. A. Myers. The diet of coastal breeding Hooded Crows (Corvus corone cornix). Ecography 15, 337–346 (1992).

Synchronised diving

I watched two drake Goosanders as they dived for food today. As soon as one dived, the other followed suit and they did this repeatedly, it was lovely to watch. Here is a distant clip.

 I then remembered a line of five fishing female Goosanders last year in a Swiss lake, swimming and diving in an orderly line along the shallows. They were behaving as if they were fishing cooperatively: by rounding up fish they would increase each of the individuals success rate. This cooperative fishing has also been observed in Cormorants and in the close relative of the Goosander, the Red-breasted Merganser.

The five female Goosanders fishing in a line, the individual at the far end peers under the water.

More information
Des Lauriers, J. R., & Brattstrom, B. H. (1965) Cooperative feeding behavior in Red-breasted Mergansers. The Auk, 639-639.