The Sea Empress oil spill (Wales, UK): effects on Common Scoter Melanitta nigra in Carmarthen Bay and status ten years later.

Carmarthen Bay, UK, regularly supports internationally important numbers (>16,000) of non-breeding Common Scoters Melanitta nigra. The spill of 72,000 tonnes of crude oil from the Sea Empress in 1996 affected birds both through direct mortality and likely pollution of key food resources. Numbers were greatly reduced following the spill, whilst changes in the distribution of birds within Carmarthen Bay suggested that potentially sub-optimal foraging zones were used. However, ten years after the incident, numbers of Common Scoter were no different to those recorded immediately before the spill. Compared to some other spills, rapid revival is evident. Numbers increased to pre-spill levels within three winters and distributional changes suggested a concurrent return to previously contaminated feeding areas, implying that the ecosystem had regenerated sufficiently to support its top predator. The importance of prolonged, standardised monitoring of bird numbers and distribution as indicators of ecological recovery from environmental damage is emphasised.

Accurate route demonstration by experienced homing pigeons does not improve subsequent homing performance in naive conspecifics.

We describe an experiment that uses the grouping tendencies and navigational abilities of the homing pigeon (Columba livia) to investigate the possibility of socially mediated information transfer in a field setting. By varying the composition of paired-release types, we allowed some naive birds to receive an accurate demonstration of the home route whilst others were paired with similarly naive conspecifics. After this 'paired phase', we predicted that if any learning of spatial information occurred then naive members of the former pairs would outperform their untutored conspecifics when re-released individually during the subsequent 'single phase' of the experiment. This prediction was not confirmed. Neither homing speed nor initial orientation was superior in individually released tutored versus untutored birds, despite the fact that both performance measures were better in the earlier 'paired phase' with experienced demonstrators. Our results suggest that although naive homing pigeons clearly interact with their experienced partners, they are unable to transfer any individually useful spatial information to subsequent homing flights.

Prenatal delta-9-tetrahydrocannabinol in the rat: effects on auditory startle in adulthood.

Either 15 or 30 mg/kg of delta-9-tetrahydrocannabinol (delta-9-THC) was administered to pregnant rats by gastric intubation from Day 2 through Day 22 of gestation. Pair-fed and nontreated groups served as controls and all treated and control litters were surrogate fostered at birth to untreated dams. When treated and control male and female offspring were tested for differences in auditory startle at 57-60 days of age, no effects were observed among any of the groups. These findings are compared with other neurobehavioral studies of adult offspring prenatally exposed to cannabis.

Prenatal delta-9-tetrahydrocannabinol in the rat: effects on postweaning growth.

Either 15 or 30 mg/kg of delta-9-tetrahydrocannabinol (delta-9-THC) was administered from Day 2 through Day 22 of gestation. Pair-fed and nontreated groups served as controls and all treated and control litters were fostered at birth to untreated dams. When weighed at 57-60 days of age, pair-fed controls were significantly heavier than the nontreated, whereas the treated animals were intermediate between the controls. These findings are discussed with respect to nutritional studies that have reported postnatal growth enhancement following prenatal maternal undernutrition and the possibility that prenatal delta-9-THC inhibits this effect.

Prenatal phencyclidine in rats: effects on apomorphine-induced climbing.

Either 5 or 10 mg/kg of phencyclidine (PCP) in saline was administered by subcutaneous injection to gravid dams during the last two weeks of gestation. A pair-fed control group was administered the vehicle alone and allowed to eat and drink only the amount consumed by the 10 mg/kg group on the same gestation days. A nontreated control group was left undisturbed during pregnancy. All treated and control litters were fostered at birth to untreated dams. Among the dams receiving 10 mg/kg of PCP, food and water intake was initially reduced to 33-43% of nontreated controls, but then returned to control levels. Surprisingly, after 3 days of drug administration, water intake of PCP-treated dams exceeded that of the nontreated dams by approximately 15%. Compared with the nontreated dams, both PCP groups and pair-fed control dams gained significantly less body weight from conception to term. PCP had no significant effect on number of implantation sites or number of live births, however, PCP produced an apparent selective embryolethal effect on males and body weight reduction in all groups at birth. Prenatal PCP did not alter the sensitivity to apomorphine-induced climbing behavior during the second postnatal week. These results are discussed with respect to published animal and clinical studies of PCP exposure during pregnancy.