We are using cavity-nesting birds to test predictions from ecological risk analyses performed at Los Alamos National Laboratory, New Mexico, USA. The site contains more than 2000 locations where radionuclides, heavy metals, and other contaminants were released to the environment. A simple model was used to predict exposure of Western Bluebird Sialia mexicana to contaminants. The estimated exposure then was compared to reference toxicity values at approximately 4000 soil sampling locations to produce an index of hazard. Inorganic contaminants (Ba, Cd, Cr, Cu, Hg, and Pb) were most likely to produce high hazard index values. PCB and DDT hazards were also identified at a few locations. Radionuclides had relatively low hazard indices. We used the resulting index values to rank the relative hazard across the study area, and then placed nest boxes along the putative hazard gradient. A second iteration of modelling is being used to refine estimates of bluebird exposure around individual nest boxes. Our updated estimates of exposure and results from nest box monitoring are being analysed by semi-parametric Cox model regression. This analysis assumes that the probability of a nest failing during a small time interval is correlated with the hazard index values. Other measurements believed to be correlated with fitness, such as nestling growth rates, immune response, and blood parasite loads, also are being used to identify adverse effects of contaminants. 

Key words: pollution, risk assessment, spatial modelling, Sialia mexicana, Cox model regression

Birds are exposed to chemicals that can cause developmental defects. Most studies examine effects in the laboratory, or report levels in wild birds, but the relationship between dose, tissue levels and effects is seldom examined. We summarise a 10-year research program that uses herring gull chicks to examine the relationship between dose, tissue levels, and response to lead in the laboratory and nature; and compare levels that cause deficits to those that occur in wild birds. Laboratory studies show that lead affects neurobehavioural development. There are critical periods for the effects of lead, and different behaviours have different critical periods. Response latency may be affected most when exposure occurs at one age, while accuracy of response may be affected more at a different age. There is not necessarily a correlation between impairment and recovery trajectory. Field experiments show similar lead-induced neurobehavioural deficits, but recovery occurs sooner in the field compared to the laboratory. Parents partially compensate for the behavioural deficits and succeed in getting chicks to a similar fledging weight as control chicks. Although survival is lower in lead-injected chicks in the wild, it is not as low as predicted because of parental behaviour. These impairments result in lower survival. Data on exposure, as indicated by lead levels in feathers of birds, suggests that some bird are at risk of neurobehavioural impairment from lead. Lead toxicodynamics also are affected by exercise. This work provides a model for studying the neurobehavioural effects of any chemical on wild populations. 

Key words: bioindicator, neurobehavioural, development, extrapolation, risk

Western Malagasy deciduous forest is highly fragmented, degraded in many areas and under great pressure from subsistence agriculture. Its bird community includes several species not found elsewhere. Bird conservation initiatives need to be focussed on the species under the greatest threat. Transect surveys were conducted to evaluate variation in the bird community between sites. Forest degradation was measured by forest structure changes. DECORANA analyses of bird community and forest structure variation showed that inter-site variation, for forest structure as well as the bird community, over a large latitudinal range, was less than that between adjacent degraded and non-degraded sites. Diversity and species richness were about equal in primary and secondary forest, although species turnover was almost complete between these forest types. Secondary forests having similar structure to primary forests held few or no primary forest species. Malagasy endemic species were almost entirely restricted to primary forests. Many primary forest species were absent in forests having less than 60% canopy cover. Terrestrial and understorey insectivores were most sensitive to disturbance. Extensive tracts of primary western Malagasy deciduous forest will be required to conserve this remarkable and characteristic bird community. 

Key words: Madagascar, forest birds, bird communities

Tropical rainforests face the danger of being either cleared completely or degraded. And yet, not much is known about the consequences of these human activities in terms of loss of the biological diversity. In this paper, I analysed and compared data obtained from intensive and extensive bird surveys of various isolated forest fragments and degraded forests in Uganda. These data were collected between 1988 and 1993. The relative importance of each habitat type was examined by the level of species loss and population decline. Results indicate that the effects of forest fragmentation outweigh that of degradation. Conservation efforts should aim at halting forest fragmentation and restoration of degraded forests. 

Key words: avifauna, fragmentation, degradation, conservation

Since the 1970s, there have been serious declines in many of Britain's farmland bird populations. In 1992, a European Community initiative designed to reduce farm surpluses led to considerable areas of arable land being ‘set- aside’, that is, left uncultivated and untreated with pesticides for periods of between one and five years. Could these areas prove beneficial to wildlife in the short-term? In 1996 and 1997 we measured the relative spatial distributions of 32 bird species on 90 farm plots across England, with respect to the availability of different field types, including set-aside. A compositional analysis reveals preferences for set-aside by a broad range of foraging species (including insectivores, seedeaters, passerines and non- passerines), while ordination techniques identified responses to environmental gradients on set-aside itself. One implication is that birds respond quickly and positively to the introduction of low-intensity farming regimes. Methods to integrate these within intensive landscapes are recommended to help maintain farmland biodiversity. 

Key words: conservation, biodiversity, cropping, distributions

Breeding skylark populations have halved between 1968 and 1995 on lowland British farmland. We examined whether differences in skylark density, productivity and habitat use on organically and conventionally managed farms supported the hypothesis that agricultural change has caused the decline. Organic fields and land set-aside from production supported higher densities than conventionally cropped fields. Nests were built in vegetation 20 to 50cm tall. Breeding success was lowest in conventional cereals, where most instances of starvation occurred, and highest in set-aside and organic cereals. Foraging adults preferred set-aside land and grass covers, but avoided conventional cereals. Our data suggest that skylark pairs must make two to three nesting attempts per season to sustain population levels. Mixed farms with diverse crop mosaics allow skylarks to make multiple nesting attempts without territory enlargement or abandonment. Recent farm specialisation, loss of crop rotations, autumn-sowing of fast-growing crop varieties, and increased agrochemical inputs are likely to have reduced the density of skylarks that can be supported on lowland farmland, and their breeding productivity. 

Key words: Skylark, conservation, agriculture, intensification, demography

Recently, tourism to seabird breeding localities has commenced in South Africa, and it is likely that the seabird ecotourism industry will grow rapidly in the future. The Jackass Penguin Spheniscus demersus is an endemic species of conservation concern, and is fast becoming a very popular tourist attraction. It is vital that tourism to the breeding localities of seabirds is sustainably managed, based on sound scientific advice. This study examines the potential impact of disturbance by tourists to the Jackass Penguin colony at Robben Island. By means of simulation modelling, the population dynamics of Jackass Penguins under different scenarios of disturbance are examined. In addition, the impacts of disturbance on reproductive performance were measured at Robben Island by comparing disturbed areas with control sites. Statistical analysis of data collected at Robben Island from 1990 to 1997 indicates that tourism to the penguin colony was maintained at a sustainable level during these years. Based on model predictions and monitoring work, recommendations are given for the future sustainable management of ecotourism to this breeding colony of Jackass Penguins. This is important as a major increase in number of tourists to the colony is planned from 1998. 

Key words: Jackass Penguins, ecotourism, management, disturbance, impacts.