Friday, 22 December 2006

22nd Whales, shags, ruddy ducks et al

Heysham Obs
In the absence of a geek and cheeky girl, the local press have concentrated today on a dead whale spp washed up at Red Nab/Ocean Edge. The species is currently not known but it is about 12 feet long and is decomposed. See,12762 for picture

Outfalls/Red Nab
2 x 1st W Little Gull, Ad Kittiwake

Harbour/north wall
c20 Shag and Ad & 1st W Med Gulls

One Brambling 'pished' but none at Barley Bank (nr Lowgill) nor any Xbill in fog-bound Thrushgill (upper Hindburndale)

Here is the latest from DEFRA on Ruddy Ducks. The hybridisation section is interesting.

UK Ruddy Duck Eradication Programme – Protecting the White-headed Duck
Briefing issued on behalf of the Oxyura Project Advisory Group

22nd December 2006

The white-headed duck is threatened with extinction by hybridisation with the North American ruddy duck – introduced to the UK in the 1940s. In 1992, the Government set up a task force to investigate the most effective way for the UK to help conserve the white-headed duck. Between 1992 and 2005, the Government commissioned research on a range of control methods including a three-year, extensive control trial. This showed that eradication of the ruddy duck was feasible and that shooting was the most effective means of control. Following the three-year trial, in March 2003, the then Environment Minister, Elliot Morley, announced that the Government agreed in principle to the eradication of the ruddy duck in the UK. Funding for the eradication programme was confirmed in October 2005. The programme began in autumn 2005 and is expected to last five years, with the aim of eradicating ruddy ducks from the UK. The control is being carried out by specially trained staff of the Central Science Laboratory (an Agency of Defra), with the General Directorate for Biodiversity in Spain as a partner organisation. The eradication project is co-financed by the EU-Life Nature Programme and Defra, with each providing about half of the total project cost of £3.337million.

Key briefing points
It has been suggested that there has been a great reduction in UK ruddy ducks moving to Spain. The figures describing numbers of ruddy ducks/hybrids shot in Spain do not support this conclusion. Annual numbers have never been large – in the last 10 years, numbers of ruddy ducks in Spain have fluctuated between 7 and 27 birds annually – but could easily become so should no action be taken to curb the increase in the UK population. Hybridisation occurs even at these low levels, and would increase with more ruddy ducks reaching Spain. The Spanish authorities believe their task will become progressively more difficult and ultimately impossible if ruddy ducks are allowed to increase in the UK and continental Europe.

It has been suggested that milder winters in the UK will cause ruddy ducks to become permanently resident. There is no guarantee of this. We cannot predict exactly how ruddy ducks will react to milder winters, especially in the context of an increasing population subject to no control action. Should winter food resources become limiting, for example, movements onto the continent might be expected. One major incursion could provide ruddy ducks with a foothold in Spain – which the Spanish authorities have, until now, denied them. The only sensible and sustainable course of action is to eradicate ruddy ducks from the UK and elsewhere in continental Europe.

It has been suggested that ruddy ducks arriving in Spain originate from European countries other than the UK. It is highly likely that the majority of ruddy ducks arriving in Spain originate from the UK, which holds the bulk of the breeding population. At present, the number of ruddy ducks breeding in the wild on the continent is small and may not be self sustaining. However, there is a danger that this will change if there are increasing numbers reaching the continent from the UK or if birds escape from captivity.

It has been suggested that only a few countries are taking action to control ruddy ducks. In fact, by 2004, at least 14 countries in the Western Palearctic had taken some action to control ruddy ducks (Belgium, Denmark, France, Hungary, Iceland, Ireland, Italy, Morocco, Netherlands, Portugal, Spain, Sweden, Switzerland, and the UK). This compares with only six countries in 1999. At least 472 ruddy ducks and hybrids have been controlled in six countries excluding the UK (Denmark – 1, France - 246, Iceland - 3, Morocco - 2, Portugal - 3, and Spain - 217) and a further three countries have indicated that attempts will be made to shoot birds if they occur (Hungary, Italy and Slovenia). Concerted eradication programmes are in operation in four countries (France, Portugal, Spain and the UK) and one is planned in Morocco.
It has been suggested that the UK eradication programme is unlikely to meet its targets. Between 1993 and 2005, the UK Government undertook extensive research to determine the most effective techniques for controlling ruddy ducks. This research confirmed that eradication of the ruddy duck from the UK was feasible and that shooting was the most effective means of control. The eradication programme began in autumn 2005. In the first year, 1,500 ruddy ducks were culled on 40 sites in England and Wales, representing approximately 34% of the total UK population. A co-ordinated count at the top 50 ruddy duck sites in the UK in December 2006 suggested there had been a significant reduction in the national population. However, this needs to be confirmed by a further coordinated count in January 2007.

It has been suggested that the Spanish population of white-headed ducks has recovered to 3000-5000 individuals. The population, which recovered from a low point in the late 1970s, is around 2,500 individuals (Hughes et al. 2006). Following a peak of 4,489 white-headed ducks in Spain in autumn 2000, peak annual counts between 2001 and 2005 averaged 2,470 birds. In global terms, it is the only expanding population, thanks to significant and sustained efforts by the Spanish authorities and conservationists leading to habitat protection and a ban on hunting. The global population is estimated at fewer than 15,000 individuals (Hughes et al. 2006). Ruddy ducks are also spreading eastwards towards Turkey and central Asia where they will threaten the largest remaining population of white-headed ducks. Local control in Turkey would probably be impossible because of the huge area of wetland. It is therefore essential that prompt action be taken to prevent ruddy ducks from becoming established in Europe.

It has been suggested that the threat posed by hybridisation with ruddy ducks is receding as numbers of white-headed ducks increase in Spain. Hybridisation remains the most important threat to white-headed ducks. An understanding of the species’ respective mating strategies confirms than an increasing population of white-headed ducks in Spain is no guarantee against extensive hybridisation. Male ruddy ducks are not territorial and many mate without forming stable pair bonds with females. Males attempt persistently to mate with females, of both their own and other species. Dominant male white-headed ducks form stable pair bonds, defending a territory containing their mate or mates. Because of these naturally differing mating behaviours there is a strong probability that, when hybridising freely, male ruddy ducks will experience much higher mating success than male white-headed ducks. The white-headed duck is in danger of becoming genetically ‘swamped’. In such situations it is well documented that extinction can result (Rhymer 2006). The mallard, which has a similar breeding strategy to the ruddy duck, now threatens seven waterfowl taxa with extinction through hybridisation and competition. Of these, the New Zealand Grey Duck is already nearly extinct. The ruddy duck’s mating behaviour means that males are likely to out-compete white-headed duck males in the mating stakes – resulting in a rapid transfer of ruddy duck genes into the white-headed duck population. Once ruddy ducks are established on mainland Europe, it will be too late to contain the problem and therefore, the precautionary principle must apply.