A Fixed Netting System as a Means of Excluding Birds From a Domestic Waste Landfill

Many bird species are attracted to landfills which take domestic or putrescible waste. These sites provide a reliable, rich source of food which can attract large concentrations of birds. The birds may cause conflicts with human interest with respect to noise, birds carrying litter off site, possible transmission of pathogens in bird droppings and the potential for birdstrikes. In the UK there is an 8 mile safeguarding radius around an airfield, within which any planning applications must pass scrutiny from regulatory bodies to show they will not attract birds into the area and increase the birdstrike risk. Peckfield Landfill site near Leeds, West Yorkshire was chosen for a trial of a netting system designed to exclude birds from domestic waste landfills. The site was assessed for bird numbers before the trial, during the netting trial and after the net had been removed. A ScanCord net was installed for 6 weeks, during which time all household waste was tipped inside the net. Gull numbers decreased on the site from a mean of 1074 per hourly count to 29 per hourly count after two days. The gull numbers increased again after the net had been removed. Bird concentrations in the surroundings were also monitored to assess the effect of the net. Bird numbers in the immediate vicinity of the landfill site were higher than those further away. When the net was installed, the bird concentrations adjacent to the landfill site decreased. Corvids were not affected by the net as they fed on covered waste which was available outside the net throughout the trial. This shows that bird problems on a landfill site are complex, requiring a comprehensive policy of bird control. A supporting bird scaring system and clear operating policy for sites near to airports would be required.

THE CONTROL OF VERTEBRATE PROBLEM ANIMALS IN THE PROVINCE OF THE CAPE OF GOOD HOPE, REPUBLIC OF SOUTH AFRICA

The policy of the Cape Provincial Department of Nature Conservation is based on the concept of "wise management" of wildlife resources. Where crop damage is real, control measures are essential. These, however, must be adapted to the species concerned and applied only where the damage is taking place. Blanket measures which also kill many useful species must be avoided. For this reason, the control of problem animals should be vested in the agency concerned with wildlife conservation.

SIDE EFFECTS OF PERSISTENT TOXICANTS

As you can see from the general tenor of the printed program for this seminar, I am in the unenviable position of trying to discourage you from certain types of chemical control; but my assigned topic "Side Effects of Persistent Toxicants," implies that mission. However, my remarks may be somewhat anticlimax at this time, because it is now generally conceded that we need to reevaluate certain chemicals in control work and to restrict or severely curtail use of those that per¬sist for long periods in the environment. So let me detail my reasons for a somewhat negative attitude toward the use of the persistent hydrocarbons from my experience with the effects of these materials on birds. But first a few words of caution about control work in general, which so often disrupts natural processes and leads to new and unforseen difficulties. As an example, I think of the irruption of mice in the Klamath valley in northern California and southern Oregon in the late '50's. Intensive predator control, particularly of coyotes, but also of hawks and owls, was followed by a severe outbreak of mice in the spring of 1958. To combat the plague of mice, poisoned bait (1080 and zinc phosphide) was widely distributed in an area used by 500,000 waterfowl each spring. More than 3,000 geese were poisoned, so driv¬ing parties were organized to keep the geese off the treated fields. Here it seems conceivable that the whole chain of costly events--cost of the original and probably unnecessary predator control, economic loss to crops from the mouse outbreak, another poisoning campaign to combat the mice, loss of valuable waterfowl resources, and man-hours involved in flushing geese from the fields--might have been averted by a policy of not interfering with the original predator-prey relationship. This points to a dilemma we always face. (We create deplorable situations by clumsy interference with natural processes, then seek artificial cures to correct our mistakes.) For example, we spend millions of dollars in seeking cures for cancer, but do little or nothing about restricting the use of known or suspected carcinogens such as nicotine and DDT.