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WILDLIFE OF NORTHERN ENGLAND

Avocet, Recurvirostra avocetta

Line drawing courtesy of the USFWS.

The avocet belongs to the Order Charadriiformes { they were formerly placed in Grallidae} and the Family recurvirostridae} and placed in the genus Recurvisostra. It is a wading bird in the true sense of the meaning.

Their form, their principle habits and their principle haunts are also their distinctive markings make them a singular and fascinating genus.  

The American avocet. Image courtesy of Dan Pancamo CC BY-SA 2.0 {Flickr}

Description and life style of avocets

The avocet is a handsome bird, the plumage close and glossy is usually  black and white giving the bird a neat clean appearance. The legs are very long, but strong and well jointed and situated on the birds body so that the bird walks in a confident and stately manner. The hind toes are little more than rudimentary , but the front three toes are perfectly formed, they are firm, but pliable, so that the bird can rise up on them when such movement is necessary.

The feet are only half webbed but the webs are uniquely formed and they are adapted to walk over soft oozy surfaces and not, as in the case of many other species,adapted for aiding the bird to swim. If the place in which it walks is very oozy the bird plants the breadth of its foot which prevents it from sinking. However, if the place on which it walks is hard and firm or covered with gravel the bird is capable of rising up upon its toes so as the toes rest between the nodules of the gravel thus avoiding injury to its foot. Among all the diverse range of birds feet, there is not one adapted to the place in which the creature feed , than the foot of the avocet.

If it should become necessary the bird can wade out to a considerable depth without wetting a feather for the legs are long and the tibia bare flowers to nearly half their length. The muscles that move the legs are very strong and compact, which enables the bird to wade for a  very long time in water or in sludge without tiring.

The neck of the avocet is long and flexible, but at the same time strong and well supplied with muscles, so that it works properly and powerfully in those directions which the habit of feeding is required.  the head is of a moderate size and the head, neck and undersides are feathered in the same manner as water birds, so they sustain no injury and indeed hardly wetted when emerged in water.

The bill is very distinctive, being long and flexible allowing the bird to find food by touch. However, the peculiarity of the bill is its shape. Most sentient bills { having the power of sense perceptive} are straight or nearly so {snipe and woodcock} and some have a slight inclination upwards, but the bill of the avocet turns upwards with a bold curve, especially towards the tip, the point of the upper mandible projecting a little beyond the point of the upper.

This unusual shape may seem a little strange and indeed clumsy in appearance. However, nature in its wisdom does not produce anything in its world that is of no use, and no matter how it may look to us, this unusual shape is very fit for the purpose for which it is intended. it is not designed for finding food on land,or, for catching fish in water. the avocet feeds when the general surface of the mud is clear of water, and there are only little runs trickling along the hollows. The number of creatures of living creatures that the mud contains or the ooze or light gravel is immense, worms, larvae and crustaceans are abundant as is the immeasurable number of fish spawn.

This accumulation of creatures just beneath the mud are not seen by birds that feed by sight, and are not stationary enough to be bored or dabbled for, are the harvest of the avocet.  it moves along the runs with slow but somewhat lengthy steps and scoops the ooze or mud in sweeps left and right as it proceeds. during this scooping process it does not use the  bill alone  but its whole body. The fixed point of this joint action is the feet, positioned to enable the bird to employ a wide sweep. The bird walks along the centre of the run, or hollow of this small watery course and it swings its beak along it has it moves along. it feeds by walking against the current so food is constantly being brought towards it then stretches and depresses the neck and gives it a twist, so that the extremity of the bill, which is on a level with the ooze, is turned to the other side. Once the food has been scooped it raises its head and bill for the purpose of conveying the food to the gullet.

Avocet

Courtesy of Andreas Trepte CC BY-SA 2.5 License.

Avocets are birds of retirement, birds which inhabit places far away from man and his buildings. The birds have no weapons of defence whatever, apart from flight, they tend to inhabit places of seclusion, or concealment. When their habitat is under threat for example by drainage or other industrial  projects the avocet disappears once they have left they seldom if ever return.

Recurvirostra avocetta the species found in the UK are 44cm long with a wingspan of 78cm and they weigh 280g. The female lays 3-4 eggs which are incubated for 23-25 days. The single brood fledges at 35-42 days. 

Recurvirostra avocetta pair.

Courtesy of Tim Strata  CC BY-SA 2.0 License originally posted to Flickr.

Conservation Issues.

Avocet numbers in the UK have fluctuated for many years. The first recording of these birds were in 1666. Once relatively common they were persecuted to almost extinction and with the loss of habitat due to fragmentation and drainage schemes and from being hunted. They recolonised certain areas when coastal marshes were flooded. They have since been recorded mainly in the southern and south eastern counties of the country. There are isolated pairs in the north west of England.

They are placed on the Amber list of conservation concern { losses of population numbers/distribution of between 25-50% over the last 40 years or so} . Avocets are continually monitored for population numbers and their distribution. Avocets now number around 1,500 pairs in Britain.

European numbers are estimated at 37-54,000 pairs, here they are not considered to be threatened.

                 Figures courtesy of the BTO.

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