Saturday, 28 February 2015

Busking Mute swans

In a visit to a local fishing lake, we find the swan family, the pair and a young from last year. The male kept his wings arched high over his body, staying between the shore, where several dogs were running around, and the other two swans. This behaviour is a mild form of threat display called busking (yes, another type of street performance if you like). Swans not only use it to deter potential predators, but also as a threat against intruding swans, before lunging or chasing them out of their territory. In its highest intensity, the display involves the swan arching its neck, and keeping its head low under his wings, while they lunge forward to the intruder swimming fast, propelling themselves with both feet at the same time. It is a most impressive sight.
Male swan busking a juvenile, note the front wave he is creating! (North Cave wetlands, 3/3/14).
The young one has a pink, instead of orange bill, and will probably stay around until the pair start nesting in the spring.
Today, at some point the dogs got too close to the shore and the female approached...
...also displayed. 
The male, or cob, swan.

Wednesday, 18 February 2015

Four calling pigeons

I had this little project in my mind for a long time, to get photos of all four local pigeon species as they call. What I had not anticipated was that I would do in in a single day in the space of 15 minutes, all in a very small area. All pigeons are now in full blown song and courtship. When I spotted the Woodpigeon above, he wasn't calling, it appeared to be just enjoying the sun, but as I walked away, I heard it calling and I turned back. The noise of the roadworks didn't stop it calling.
It is unusual to see a Collared Dove calling in the park.
Not much further away, a Stock Dove started calling. This ash is their favourite tree, and most of the time there are two or three there. Stock doves are quite timid, and they call from high vantage points.
To end the series, it wasn't too hard to find the courting Feral Pigeons, there were plenty around. This male and watchful female were on the roof of the cafe at Pearson Park. 

Sunday, 11 January 2015

Pinkfeet together

At East Park this morning we came across a Greylag flock by the cafe lawns. I spotted the Pinkfoot, and then another, which surprised me. There has been a resident Pink-footed goose in East Park for a year now, a young bird flocking with Greylags. In November, I had spotted a different bird (and blogged about it, see here), also with Greylags at Pearson Park. Could these be these two birds that had got together?
 I looked carefully at my photos and saw that they have distinct bill markings, one with a very small mark close to the nail, the other with a larger U shape mark. The older bird, with the U shape mark (I'll call her Stripe) appears to the the East Park resident. The younger bird, still with tiny body feathers has a small bill patch and matches the bill marks - and tiny white feathers around its bill - of the one that was at Pearson Park. Despite being younger, this bird was bigger and has a larger head, with a Roman profile and a thicker neck and a heavier head, so it might be well a male. Since last saw both birds I was impressed how much more grown up they look. Their neck stripes are better delineated, their head shapes less gentle, and they have a more silvery backs as they have moulted their juvenile feathers. The Pinkfeet stayed near each other in the flock, but one lunged at the other when it got too close. At some point the flock got wary of a radio controlled car, and after a crescendo of cackles, they flew off.
'Dot' Pearson Park 20/11/2014
East Park, today. A male?
'Stripe' East Park 14/2/2014
East Park, today, a female?

Dot's juvenile feathers very noticeable in the flanks, with some adult feathers, darker and silvery just over his legs.
Stripe seems to have a full adult plumage now.

Wednesday, 3 December 2014

Gritting greylag geese

Birds that feed on fibrous or hard food of vegetable origin often swallow sand or small stones ('grit'). Grit accumulates in the gizzard or crop, and together with the muscular action of the crop it helps macerate their food facilitating digestion and increasing food processing rate. The limited size of the gizzard means that herbivorous birds need to spend time just processing food, waiting until the gizzard empties, before another foraging bout. Grit can be ingested accidentally with the food or purposefully, by visiting places where it is easy to find. Wintering flocks of Greylag goose in Doñana National Park (Spain) visit sand dunes to ingest sand, and their crop can hold up to 10 g of sand.  Birds can adjust the amount of grit to their diet and in turn, crops containing more grit become more muscular, flexibly responding to the demands of different coarseness or amount of fibre in the diet.
 While watching the flock of wintering geese in my local park, I noticed them stopping in a bare area. First I thought they were feeding on the small tufts of grass there, but when I looked closer I realised they were ingesting grit. They spent a few minutes doing this, and then moved onto the grass to feed. The distinctive individual with a white head (above) serves as an identifier for this flock. I have seen him or her both at East Park and Pearson Park.
A pair gritting together.
Here is a short video of the behaviour:

More information
Amat, J. A., & Varo, N. (2008). Grit ingestion and size-related consumption of tubers by Graylag Geese. Waterbirds, 31(1), 133-137. here.

VerCauteren, K. C., Lavelle, M. J., & Shively, K. J. (2003). Characteristics of grit in Canada goose gizzards. Wildlife Society Bulletin, 265-269. Here.

Friday, 21 November 2014

In the wrong flock

Although I wouldn't consider Pink-footed Goose (also known as Pinkfoot) to be an urban bird, it is a species that I regularly see. Skeins of this migratory geese, announced by a chorus of high pitched calls, regularly fly over the city in October and March, on their way to and from their breeding headquarters in Iceland and Greenland. Occasionally, however, a straggler will turns up with Greylags in local parks, allowing a closer look.
  On my way to work, walking through the park, a flock of Canada Geese and another of Greylag geese were about. While counting them I noticed a much smaller goose, a Pinkfoot, amongst the greylags. They have small bills, marked with pink, much darker head, contrasting with the slaty back. I think this individual was a young bird born this past summer, as you can see two types of feathers in its flanks and back, as the larger adult feathers, with a pale edge, have started to grow. The furrows that adorn the neck of adult geese are not yet sharply defined. The goose wasn't welcome and was often lunged at by the Greylags. Surprisingly, it was quite relaxed in the park, despite proximity to people, and it got very close to me as it followed the other geese across the lake and then to the grass to feed.
 I other occasions when had previously seen other Pinkfoot with greylags, it was also young birds. I wonder if leaving with your own species as the flock departs takes some learning. Geese need to reach a consensus before leaving as a flock, a decision that takes place by increasingly noisy vocalisations and movements of the birds of the flock when they are ready to leave. If a young bird misses the cues, it will fail to take off might miss the flock altogether, becoming stranded possibly with another geese species. Geese have long lives and move about, so most likely, while following the greylag flock in its travels, it will eventually meet a Pinkfoot flock and the young bird will be reunited with other members of its species.
A Greylag drives the pinkfoot away from its partner

Walking towards the grass. The difference in size between both species is evident here.

Sunday, 9 November 2014

Walton Street crows

We went to Walton Street market and car boot sale this morning and I couldn't help but notice the crowds of Carrion Crows. At least 50 individuals were about, on van and car roofs, atop flood lights,
 and walking amongst the huge puddles left by yesterday's rain.
Some patrolled just over the paths, elaborately flying slowly, sometimes almost hovering - in black-headed gull style - scouring the ground.
Soon it became apparent what they were after. No, they weren't hunting for antique bargains, but taking advantage from the fast food bonanza that inevitably follows human crowds.
Crow on roof van. 
A starling passed too close and made him jump
I missed the wing tip in the phot, but I like the shadow of the crow
I watched as one individual landed on the roof of a van, triumphantly holding half a hot dog sausage in its bill.
The remainder of the hot dog was being dealt with a few other crows: a dominant one pushed another aside...
...and quickly picked up the other half of the sausage in its bill, before flying away
while the other, less fortunate crows contented themselves with bread smeared on ketchup.
We associate scavenging behaviour with dirt, rotten food and germs, but I doubt the hot dog had been on the ground longer than the five-second rule allows, before it was cleared up, taken away by the crows.
But, occasionally, the bin man gets there first. Crows watched him picking a paper bag...
...but leaving some food behind, which was quickly dispatched
There were many gulls and starlings about, but I didn't see them take advantage of the market food. Crows appeared bolder, and cheekier than in other places, maybe they are all locals used to take advantage of the markets - and Hull Fair - and are used to people. This one spent some time checking itself out in the wing mirror of a car.
The it jumped to the roof and spent some time watching from this vantage point.It allowed me to approach close enough for a portrait (top shot)
 After filling their tummies, some crows took turns in the puddles for a bath.

Wednesday, 5 November 2014

Into the eye of the winter herring gull

 The resident pair of Herring gulls are back at the park. One of the individuals (above) has its full winter attire with a streaked grey head, which gives it a particularly stern look. The other one, which seems smaller (maybe the female?) still has a very white head. A young of the year is also about.