HELP WANTED PLEASE

The Raven’s loud, far carrying “cronk” call, often accompanied by a tumbling display flight, is the most evocative sound of the uplands in late winter and early Spring. The pair wheel and soar together, their flight so synchronised that the wings appear to be joined at the tips. Ravens breed very early, and most eggs are laid before the end of February.

Pairs are very territorial, and nests are widely spaced, so the population is still small, although it is increasing rapidly. The County population grew from around 50 to around 175 breeding pairs during the 1990s. It has continued to increase since, to around 250 pairs by 2003.

Mortality is high – most Ravens die before they are two years old – so many young birds are needed to ensure that enough reach breeding age. Therefore there are always more immature birds, three years old or less, than there are adult breeding birds.   Flocks of up to 80 are now being seen. Large flocks (over 10) should be reported to the County Bird Recorder, please, as these are evidence of continued breeding success and population growth.

Ravens are omnivorous, and mainly eat carrion. The population growth is attributed mainly to a better food supply from the increase in carrion left lying round the uplands – sheep carcasses used to be removed and taken to the knackers yard, but the financial incentive for this disappeared when the Government changed the regulations governing the use of materials reclaimed from carcasses, to combat the spread of BSE, in the early 1990s. Increased carrion from lambing out on the hillsides (dead lambs, and after-birth) has helped increase the number of young birds fledging, and milder winters and reduction in illegal poisoning have also reduced mortality.

The Shropshire Raven Study Group has been following the fortunes of Ravens in the County since 1994.  Little is known about how long they live in the wild, how old they are before they start breeding, and how far they move from their natal area to their adult breeding site. To answer these questions, part of the Group’s work included putting a coloured ring on one leg of each chick while it was still in the nest. Colour-rings were put on 781 nestlings from 223 nests in Shropshire , plus 20 nestlings from 6 Herefordshire nests, in the six years 1994-1999.  There is a different coloured ring for each year, and every ring has two unique letters.  

Group members are now visiting all known Raven nest sites, and trying to find new ones, to find out where the colour-ringed birds are turning up in the breeding population. If either of the nesting birds has a colour-ring, observing the colour, and reading the letters, tells us how old the bird is, and where it came from.

In 2004, 45 adult breeding Ravens were found with colour rings, with an average age of 7 years old. We managed to read 40 of them. Both birds had rings at 7 sites. In 2005, 45 were found again (38 were read), but 15 were different birds. The average age was almost 8 years old. Since the Project started, we have read the rings on 167 occasions on 70 different individuals.

A female Raven which fledged from a site close to the Welsh border in 1994 has been nesting within a couple of miles of Church Stretton for the last few years.  In 2004, she became the first wild Shropshire bird proved to reach 10 years old. In addition to this female, another 10-year-old, a male from near Ratlinghope, still had a nest near Cardington. Both these birds returned to their breeding sites as 11 year olds in 2005. Six birds ringed in 1995 were found as 10-year-olds at nest sites in 2005.

We are thus building up a picture of how old young birds are when they first breed, their life span, and how far they move. Most birds are at least three years old before they nest, usually older, and it appears that females move further from their natal site than males – presumably a natural selection defence against inbreeding. This is a nationally-important Study, as evidenced by grants from the British Trust for Ornithology, and sponsorship from Swarovski Optik (provision of a telescope to read the rings).  With your help we can learn much more.       

We need more help to check known nest sites and find new ones, please. The Raven population is increasing, and their range is expanding, so there must be many nest sites with colour-ringed birds that we do not know about.  Raven nests might be found anywhere in the County now, where there are suitable large trees for nests.

Even if you cannot help with the fieldwork, you could still provide important information. We particularly want breeding season records between February and May.  Please let us know immediately if you find:-

·        Evidence of a nest – the most commonly observed evidence of an active nest is seeing Ravens drive off other predatory birds (particularly Buzzards), but pairs displaying in February, repeated territorial calling, being aggressive to humans, or carrying nest material or food, are equally good evidence.

·        Ravens in places where they have not been seen or heard previously.

·        Ravens with colour rings on (it is possible to see whether or not a bird has a colour ring in good light, through binoculars, if it is perched, or feeding on the ground, or flying low directly overhead. A telescope is necessary only to read the letters on the ring, and we can do that for you.

We will come and check the nesting pair for colour-rings, and, if either bird has one, we will be able to tell you its life history

If you know of a Ravens’ nest, or suspect one, please don’t assume we know about it already, even if it has been there for several years!  Offers of help, and reports of Ravens, as soon as possible, please, 

to Leo Smith Tel. 01694 720296    email: leo@leosmith.org.uk

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