Sunday, 29 September 2013

House Sparrow

House sparrows have now finished moulting and males are donning their more subdued winter attire. The new feathers have buff fringes that tone down their deep chestnut head and black bib. The bill is also yellowish. This one posed for a few seconds on top of a wire fence before flying away.

Thursday, 26 September 2013

Tail flicking Moorhens

ResearchBlogging.orgThe contrasting white feathers at the sides of Moorhen tails are very obvious, especially when they flick their tails up and down, often fanned. As this one run away from me this morning I wondered what is this flicking for? An aggressive signal to other moorhens had been proposed as a hypothesis. However, observations carried out by Fernando Alvarez suggested a more intriguing reason. When a patrolling Marsh Harrier - a common predator - approached a moorhen, the rate of tail flicking increased as the moorhen dashed towards cover. In addition, the more vigilant the bird, or the further away from cover, the higher the tail-flicking rate was. These and other results suggested that tail flicking is not a signal to other moorhens, but a signal of alertness to the potential predator: 'I can see you!' This might deter the predator from chasing that alert individual and try catch a less vigilant one unawares.
 More experiments by Alvarez and colleagues suggested that moorhens in better physical condition showed higher flicking rates when foraging: healthier individuals flick their tails faster, which indicates that the signal is actually telling the predator: 'I can see you and I am fast so you can't catch me!
So both prey and predator would benefit from this honest signal of body conditions and alertness, as a chase, which would be wasteful in energy for the prey and likely to be unsuccessful for the predator, is avoided.
flicking away from me
she is definitely seen me!
she looks quite alert, but maybe then realised I pose no danger
UPDATE 3/10/2013
I took this video today of the tail flicking behaviour in the park moorhens

More information

Fernando Alvarez (1993). Alertness signalling in two rail species Animal Behaviour, 46, 1229-1231 DOI: 10.1006/anbe.1993.1315

Fernando Alvarez, Cristina Sánchez, & Santiago Angulo (2006). Relationships between tail-flicking,morphology, and body condition in Moorhens Journal of Field Ornithology, 77, 1-6 DOI: 10.1111/j.1557-9263.2006.00001.x

Wednesday, 25 September 2013

Woodpigeon school

I have come across several Woodpigeon families in the last week. August and September are peak season for Woodpigeon fledglings. One or both adults will accompany, and occasionally feed the young for a week or two. The fledglings look nervous and follow each other or their parents, feeding on the ground. After the adults leave them to their devices, the usually two siblings will move together or join other juveniles.
 In these photos, you can see the differences between the juveniles and the adult at the background. Juveniles are much smaller, they lack of white patch on the neck (but not the striated neck feathers), the beak is a dull grey and their eyes are dark.

Saturday, 21 September 2013

Mallards grunt-whistling

The drake mallards at the park have now almost completely finished their summer moult and are sporting their dazzling fresh plumage. Mallards start the breeding season quite early. The first stage is pair formation, which starts in September-October. Any unpaired females attract the attention of drakes and a flock of suitors surrounds her, parading. A trademark display of many ducks is the 'grunt-whistle'. In mallards this consists of a sequence of behaviours including a whistle, at the same time that the duck lifts both his head and tail.
 The fact that there are usually many males displaying at once and any of them can carry out the behaviour, means that I've had trouble recording in it a photo previously. By the time I head a whistle, or several, I have missed the behaviour. This week in the park, when I noticed the mallards courting, I decided to focus on a particular male and try and catch him doing it.
 The first step of the grunt-whistle sequence looks like the duck is about to dive. Instead, he arches his head forward forcefully, and his bill tip scoops an arc of water droplets toward the female. I managed to get two shots of this stage. The second shows the droplets quite well.

Then is the whistle, while lifting the tail and head (note the bill is a little open).
After that, the drake turns to the female (top shot), and then swims fast with head forward, almost touching the water.
I will try and get a video of the whole sequence in the next few weeks and upload it here.

More information
Wolfgang M. Schleidt & Erhard Oeser (2011) Konrad Lorenz’s use of cinematic film for studying dabbling duck courtship behaviour and the availability of historic film materials. Wildfowl 61: 45–51. Here.

Friday, 13 September 2013

Lesser Black Backed gull

Three different gull individuals, a Herring Gull, a Lesser Black Back, and a Common Gull arrived at the park and flew in circles around the pond, their keen eyes looking for food. Several people come early in the morning and leave bread and scraps on the side. After finally landing, before coming to the food, this Lesser Black Backed gull had a good look around, a bit nervous. Once the other two gulls landed, they all went in with the feral pigeons to eat.

Saturday, 7 September 2013

Watching Mistle thrushes

A pair of Mistle Thrushes are resident in my local park. They are very used to people and can be quite approachable. I watched three of them, maybe a family group, feeding on the grass, 4-5 m away from me. One of them even came closer as it fed on worms.

Friday, 6 September 2013

Woodpigeon eating elderberries

The elders are now fully laden with a plentiful berry harvest. Early this morning, a group of nervous starlings came up and down to one, feeding on the berries. A relaxed woodpigeon stretched and fed as well. The light wasn't perfect, and the birds a bit far, but I like that the berry bunches are still pretty much intact. Elder provides berries from mid August to early November. In their monograph on Birds and Berries, Barbara and David Snow recorded 16 species of seed dispersers and 6 of seed predators feeding on elder berries, the largest diversity of species for any other fruit. Numerically, Starlings were the most common, followed by Blackbirds, but other thrushes, migrating warblers, robins, corvids and even moorhens were recorded feeding on berries. Woodpigeons, after Blue Tits, were the main seed predators, although woodpigeons can also be seed dispersers of this fruit.