Hertfordshire News, Comment and Bulletin articles
This month
Coto Donana contamination update
Tree Sparrow Initiative update
Do Lesser Black-backed Gulls breed in Hertfordshire?
Herts Bird Club/BTO Annual half-day Conference
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Coto Donana Contamination Disaster Update
The traces can still be seen on the magnificient oaks that line the River Guadiamar in Southern Spain. The bark on some of the trees is darker is the rest of the trunk to a height of about a metre above the ground - almost as if they have been painted. This colouring is a reminder of one of the worst environmental disasters in Europe. A year ago on the 25th of April a 5-million cubic metre flood of poisonous sludge erupted out of the damaged drainage-basin of a mine and poured over a vast area near the Donana Nature Reserve near Seville. The reserve is Europe's largest bird sanctuary.
In the meantime thousands of tons of contaminated earth have been carted away - 400 lorry loads a day over a six-month period. Nevertheless, recent studies have shown that, a year after the disaster, large areas are still contaminated with heavy metals such as arsenic, zinc and lead. Miguel Ferrer, Head of the reserve's biological group is sure of one thing: "Now the problems really start". Although the poisonous flood of sludge was held back by the dam which runs parallel to the reserve, neither the birds nor the water table recognise artificial boundaries. Scientists now fear that the food chain will become contaminated. The newspaper La Vanguardia reports the results of a survey in which, as an immediate result of the disaster, dangerous levels of lead and cadmium have been measured in more than half of the 40,000 geese which overwinter in Donana.
The WWF accuses... "too little was done too late". The governmental research institute CSIC counters with the statement that it is still far too early to provide concrete proof that the birds have been adversely affected. Nature protectionists claim that Donana has been ".. mortally wounded" but this is not accepted by the Spanish Ministry of the Environment. The tourists do not seem to have been put off and it is claimed that numbers of visitors remain stable.
Environmentalists have also criticised the re-working of the pyrite mine close to the neighbouring town of Aznalcollar, which is run by the Swedish-Canadian concern Boliden Aspira. The authorities have given conditional permission for the re-opening.
This is criticised by Greenpeace as premature. Security measures have hardly been improved. "A new time bomb is ticking" says the environmental organisation. The company rejects this criticism. The mine is the most important local employer and the 6,000 inhabitants of Aznalcollar have greeted the resumption of work.
Many local farmers are waiting in the meantime for financial assistance. The banks of the Guadimar over a length of 40 km, and a total area of 6.000 hectares (some 15.000 acres) - half of which was of productive arable land - were contaminated by the sludge avalanche. Where once grain, sunflowers and soya grew is now a desert. Genetically changed crops, which draw up the contamination, are to be introduced to revitalise the land.
The legal authorities are still occupied with the question of responsibility. The Boliden company claims that responsiblity lies with poor construction of the drainage-basin - built by spanish firms. This is the conclusion of an independent expert opinion. Boliden's Company President Anders Buelow has assured the newspaper Le Pais that his company will win the legal battle. The costs to date of the clean-up are running at 14 thousand million pesetas of which Boliden has contributed roughly one third.
The scientist Cesar Nombela says that we must learn from the catastrophe. "Social consciousness with regard to the environment must be sensitived". The WWF sees this as an urgent necessity - a new study has shown that 328 of the mine drainage-basins in Spain are unstable or have dangerous cracks in them.
Tree Sparrow Initiative update
Thank you to the members who offered to help replenish the winter feeding site for Tree Sparrows at Bowmans Farm, London Colney. Unfortunately it has not been necessary to contact some of you because the sparrows showed no interest in using the feeders for most of the winter.
In the early autumn four large seed feeders, with tray attachments, were bought, along with a generous supply of mixed black sunflower and other seeds, from CJ Wildfoods who kindly gave a special discount for this project. They were sited near a hedgerow where the Tree Sparrow flock is regularly seen, over an area of quite deeply flooded rough ground. Three of the feeders were attached to an old clothes dryer 'merry-go-round' and one was hung in the nearby hedgerow.
The feeders were checked at regular intervals but all remained completely full for some months. The only feeder to have some seeds taken was the one in the hedge (we suspect by the few Blue and Great Tits that venture into this open habitat), so two of the other feeders were moved further along the hedge over dry land. These were immediately stolen. Presumably the deep water prevented the other feeders from the same fate.
Things remained much the same until mid-February, when seed from the hedgerow feeder suddenly started to be taken, followed by that from the remaining feeder. Now the seed is going fast and, whist it is difficult to observe birds on the feeders without disturbing them, it appears to be Tree Sparrows that are taking it. This is presumably due to natural foods becoming scarce at the end of the winter. We hope that now the sparrows have learned to take the seed they may start earlier next year.
A ringing programme has been started by the Maple Cross Ringing Group and so far 23 Tree Sparrows have been ringed. With a largest flock count of 54 in recent times, almost half this figure has now been ringed. The fact that no birds have been retrapped suggests that (unless we have had incredible luck in not catching any ringed birds) the flock could be somewhat larger than suspected.
Last year two pairs of Tree Sparrows bred at Bowmans Farm in natural sites. A number of nestboxes present have been modified slightly and it is hoped that birds may take advantage of these this spring.
We would ask Bird Club members to refrain from visiting the site, which is on private property, to avoid undue disturbance. We would like to thank Mr S Legerton of Bowmans Farms Limited for his kind permission to set up and maintain the feeding site and carry out ringing on his property. We should also thank Gary Elton for taking on the brunt of the work involved in setting up and running the site.
Do Lesser Black-backed Gulls breed in Hertfordshire?
Lesser Black-backed Gulls normally breed in coastal colonies, in sand dunes and on islets, but have also frequently been recorded breeding on tall buildings in city or town centres; this has been recorded in Avon, the West Midlands and London and now, perhaps, in Hertfordshire.
In 1997 a presumed pair of Lesser Black-backed Gulls were seen in Watford town centre on a regular basis (at least weekly) from early May until mid July. I first noted a bird, in mature plumage, perched on the cupola of Clements department store occasionally giving the challenging trumpeting call. The next week what was presumed to be the same bird was present again and this time a second adult was on the parapet of Abbey House, directly opposite and approximately 20 metres distant. This building is a flat-topped office block. The second adult disappeared on to the roof. On a third occasion an adult was seen to leave the cupola perch and, after a brief circuit of the roof tops, alight for a short while on the parapet before disappearing onto the roof of Abbey House. These sightings took place in the first half of May and were followed by views of adults on the cupola and other nearby vantage points, and also on the sports pitches of the West Herts Sports Club some 300 metres distant, during June.
In the first week of July two birds in juvenile plumage were seen closely pursuing an adult around the high-rise buildings of the town centre with a second sighting of presumably the same trio two days later on the cricket pitch of the West Herts Sports Club. The only other record was of an adult causing acute mayhem amongst the nesting Feral Pigeons on the high terraces of the Harlequin Centre which are planted with shrubs on the south-east face of this cliff-like structure. No further sightings of Lesser Black-backed Gulls took place until the return of autumn migrants.
In 1998 two adults were again seen in late April and into May, flying together around the same sites as the previous year and, on one occasion, a bird was seen on the Clements' cupola but no further sightings took place that year.
This year, on 4 February, two adults were seen in flight doing circuits around the same area and it remains to be seen if any further evidence can be gathered to support a breeding attempt.
All these sightings may just be the result of over-summering birds taking advantage of the thrown away take-aways that litter the town centre, but breeding on private buildings is difficult to prove conclusively. Territorial calls, the presence of juvenile birds and the fact that records ended abruptly in July after a continuous presence during spring and early summer, all give an indication that breeding may be occurring.
Birdwatchers are not the usual habitués of town centres so records are likely to be sparse. It is possible that gulls may be occupying other towns in the county I would be interested to hear from anyone who has observations from Watford or elsewhere in Hertfordshire.
Jim Terry, 46 Manor Way, Borehamwood, Herts, WD6 1QY, 0181 905 1461
Herts Bird Club/BTO Annual half-day Conference - "Monitoring methods crucial to conservation"
The theme of this year's half-day event was on why surveys and other monitoring methods are crucial to the conservation of our birds, both nationally and in Hertfordshire.
The afternoon was opened by Trevor James, head of ecology at Hertfordshire County Council, who talked briefly of his personal experiences when recording in Northaw parish from 1962. He and others made weekly counts using the same route over five years which provided useful information on changes and trends for the BTO.
The first session was chaired by Graham White and started with an expansive look at biodiversity action plans by Darren Kindersley, conservation officer with the RSPB. Biodiversity (the variety of both species and habitats) first came to public notice via the Earth Summit in Rio de Janiero in 1992. The aim was to halt, and hopefully reverse, the loss of diversity in the world. Due to limited resources targeting was seen as essential and the phrase 'think globally, act locally' was first vaunted. The Biodiversity Action Plan for the UK was brought out in 1994 and included priorities such as globally threatened bird species (like the Corncrake), those of international importance (for example the endemic Scottish Crossbill), and locally threatened or declining species. Hertfordshire's Action Plan has now been published and progress is already being made. Darren made a point about how critical monitoring is in tracking this progress.
Next was a talk by Andy Wilson on Nightingales. Andy works for the BTO and organised the 1999 Nightingale Survey. Nightingales are at the edge of their range in England and are therefore vulnerable to climate and other changes; there has been a decline in the British population over the last 30 years. This may be due to a number of causes at different stages of the birds' year: during migration (hunting or habitat loss), in winter quarters (climate change in the Sahel region of Africa, bringing about habitat loss and food reduction, and hunting) and during the breeding season (habitat loss and food reduction especially due to increasing numbers of deer browsing). The results of the 19 99 survey are awaited with interest. Money from the BTO Nightingale appeal is going towards additional research into subjects such as food supplies.
During the break for tea, when the Herts Bird Club's AGM was also held, there was time to browse the various displays and stalls in the foyer. These included BTO, Friends of Tring Reservoirs and Herts Bird Club displays and artwork by Ernie Leahy and Jan Wilczur.
Robin Smith introduced the second session, the first talk of which was on ringing and its contribution to population monitoring and migration studies. Dawn Balmer of the BTO outlined the history of ringing from its inception in Denmark 100 years ago. There are currently about 2000 trained ringers in the UK and the BTO processes some 14,000 recoveries each year. Special projects, such as the Constant Effort Sites Scheme (CES) and Retrapping Adults for Survival (RAS) are making great contributions to our monitoring of adult survival, breeding success and population levels of a number of commoner species each year. There are 130 CES sites in the UK and Hertfordshire is joint top with eight. General ringing also provides useful information on individual birds: migration routes and other movements, ages, survival, and changes in population. (Wheatears normally survive 7 years, Coots 15 and Gannets 36.) More information is needed, however, on endangered species. Target ringing can contribute to identifying reasons for decline and at what stages in the birds' life cycle this may be occurring.
The last talk of the afternoon was a duo by Ken Smith (head of the Herts Bird Club scientific committee and a senior research biologist with the RSPB) and Chris Dee (the Bird Club's chairman and our BTO representative) on what we are doing locally to monitor our birds, and what we can do in the future. The first Hertfordshire Bird Report was published in 1908 with about 6-7 people submitting records. These days around 200 observers contribute a growing mass of data each year. Hertfordshire is also involved in many national surveys organised by the BTO. The Corn Bunting survey, for example, showed that the local population had plummeted from 1046 singing males in 1983 to 190 in 1993. There have been reductions and increases in our bird populations, with species such as Lapwing and Willow Tit much reduced while Mediterranean winterers such as Blackcap and Chiffchaff have increased.
It was pleasing to hear that certain bird populations are included as part of John Prescott's indicators of quality of life. Wetland birds are always particularly vulnerable and considerable effort will be needed to reverse the downward trend with breeding Snipe. Bitterns are already receiving special attention and, with improvements in habitat happening in the Lee Valley, future breeding is a real possibility.
Overall, there was much to ponder during the afternnon. The important thread was, however, that continued scientific monitoring, by a wide variety of methods, is the only way we can determine what is exactly happening out there, and give organisations the opportunity to do something about it.
Jan and Mic Wells