Managing supplementary feeding for avian scavengers: Guidelines for optimal design using ecological criteria

Current European sanitary laws are promoting the concentration of domestic livestock carcasses in limited locations called ‘vulture restaurants’ or supplementary feeding stations in order to safeguard human health. However, this type of food concentration could lead to monopolization by a few, large dominant species. Management guidelines are urgently needed to ensure that potentially less competitive and more endangered scavengers can also benefit from this resource, considering that once abundant carcasses are now absent from the field. Here, we assess factors affecting the abundance of six avian scavenger species at 17 feeding stations in northern Spain, considering aspects such as carrion availability, physiographic features, humanization, presence of heterospecifics and densities of scavengers during both winter and summer seasons. Results indicate that conditions for interspecific facilitatory processes are possible at low numbers (<100 individuals) of griffon vultures (Gyps fulvus). Otherwise, the other avian scavengers are excluded. In a few cases, spatio-temporal patterns of segregation become apparent. Differences in the size of carcasses supplied to feeding stations as well as the local characteristics influence the balance of species at these points and, therefore, how species of conservation concern use feeding stations. Future legislation should encourage the opening of numerous feeding stations supplied with low quantities of food to mimic the original condition of temporal and spatial unpredictability of carcasses and to maintain ecological relationships within the scavenger guild.     

Fate and consumption of discarded by-catch in the Spencer Gulf prawn fishery, South Australia

Discarded by-catch in prawn fisheries is likely to affect trophic balance including the population structure and function of both the exploited species and scavengers on discards. The Spencer Gulf prawn fishery consists of 39 trawlers operating about 60 days a year with a management system allowing large differences in spatial effort. Such a system provides opportunities to study spatial effects of fishing in relation to habitat and fishing effort. In this study, the occurrence and consumption of scavengers on the Spencer Gulf prawn fishing grounds were studied at five sites subjected to different historical fishing effort and further estimated through field and laboratory experiments. Baited video experiments showed that the most common scavengers on discarded by-catch were Degens leatherjacket (Thamnaconus degeni), blue crabs (Portunus pelagicus) and sealice (a group of several species of isopods and amphipods), notably Natatolana woodjonesi, with variable abundances between sites and day/night. Scavenger abundance and consumption was higher at night than during the day. Total abundance and consumption during the day showed a negative correlation to historical trawl hours, while during the night showed a positive correlation. In the laboratory, in contrast to groups, individual leatherjackets showed little interest in bait. Consumption rates for both leatherjackets and blue crabs showed a logarithmic trend depending on bait species. The results showed that during the day blue crabs and leatherjackets were the dominating scavengers while during the night it was Port Jackson sharks and in particular sealice. The effects of site, historical trawl hours and relative importance of the scavenging species are discussed.     

韭菜种子老化因子初探

常温下贮藏1年的韭菜种子活力显著下降,膜透性明显增加,表现为浸泡液电导率升高,可溶性蛋白质、糖、无机磷和有机酸渗漏量的加大,与此同时,过氧化物和MDA含量显著增高。韭菜种子活力与膜脂过氧化程度及膜透性呈负相关,膜脂过氧化作用被认为是韭菜种子贮藏期间活力下降的原因之一。老化种子经自由基清除剂(如谷胱甘肽)处理后,发芽率有不同程度的提高,