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Cara J

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  1. Birds are the most diverse group housed by zoos around the world, but zoo-based research tends not to focus on birds. A new article published in the journal Birds, by Dr Paul Rose of the University of Exeter, suggests zoos can improve management of birds by looking at how species live in their natural habitats. Likewise, birds living under the care of humans can also help guide and develop conservation action for those living in the wild. Dr Rose explains: “Research into wild birds is extremely useful for furthering how birds are managed in zoos. For species of conservation concern, zoo professionals can be linked with field biologists to share information on how to best care for these species in captivity and how to develop and formulate conservation actions. We can use proxy species – those common in zoos – to develop practices for conservation that can be used for less familiar species that might be of concern and need help from information gathered through things such as captive breeding. Or we can promote the threats that these not-in-the-zoo species face by using the commoner species as an ambassador. We do this through my work at the Wildfowl & Wetlands Trust, promoting the rarer species of flamingo that are in the wild using the commoner ones we keep in the living collection.” In the review, Dr Rose uses hornbills as an example, a species of bird that is essential to the long viability and sustainability of biodiversity in the rainforest. The helmeted hornbill, a critically endangered species, plays an important role in the dispersal of seeds within pristine, undistributed areas of south-east Asian rainforests. The population decline of the helmeted hornbill has been caused by poaching of the birds for their “ivory,” the large casque on the bird’s head and bill that can be up to 10% of its overall body mass. Whilst the helmeted hornbill is not found in captivity, other species of large hornbill are. By looking at the ecological role of the helmeted hornbill in its natural habitat, zoos have been able to design enclosures that will increase chances of reproduction. For example, by identifying the temperature and humidity range of hornbill nesting sites in the wild which are more likely to hatch eggs, zoos have been able to use this data to enable them to match these environmental conditions as closely as possible. A similar situation happened with the Guam kingfishers, a species that is extinct in the wild and reliant on captive breeding for its survival. Data from the nesting locations of the closely related Pohnpei Kingfisher, found on a neighbouring island, showed that temperatures were hotter than those sometimes provided for captive Guam kingfishers. The findings led to zoos raising the temperature to improve nesting success amongst the species. Zoos have also been able to guide conservation action for hornbills living in the wild by monitoring the behaviour of these birds and discovering that using nest boxes enhances the quality of habitats for hornbills to breed in, which has led to these boxes being built in areas of the helmeted hornbill’s range in Borneo. “The effect of visitors on zoos can also help direct future research questions and increase understanding of birds under human care,” adds Dr Rose. “Developing zoo bird exhibits to theme them around specific conservation messages can be used to promote wider understanding of the threats faced by wild birds specifically and hopefully encourage human behaviour change that benefits ecosystem health.” View the full article
  2. Squeezed by changing ocean conditions that limit their food options and the long-term loss of old forest needed for nesting, marbled murrelets would benefit most from conservation efforts that take both ocean and forest into account, new research by Oregon State University shows. Published in Conservation Letters, the findings are based on two decades of murrelet surveys at nearly 20,000 sites in the Oregon Coast Range and illustrate how the elusive seabird is at risk of its habitat gradually shrinking to the point of local extinctions or worse. Lead author Matt Betts said: “It turns out that the same ocean conditions that influence salmon returns, including the forage fish murrelets need to successfully nest, had a huge influence on the likelihood that murrelets will come inland to breed. Given that these prey items tend to be in lower abundance when ocean temperatures are high, changing climate conditions could reduce prey availability as well as the tendency for murrelets to nest in the future.” Marbled murrelets are closely related to puffins and murres, but unlike those birds, murrelets raise their young as much as 60 miles inland in mature forests. Disturbance in either the ocean or forest environment has the potential to impact murrelet populations. “There aren’t many species like it. There’s no other bird that feeds in the ocean and commutes such long distances inland to nest sites. That’s really unusual,” said study co-author Jim Rivers. The dove-sized bird spends most of its time in coastal waters eating krill, other invertebrates and forage fish such as herring, anchovies, smelt and capelin. Murrelets can only produce one offspring per year, if the nest is successful, and their young require forage fish for proper growth and development. Along the West Coast, marbled murrelets are found regularly from Santa Cruz, California, north to the Aleutian Islands. Their populations have been declining by about 4% a year in Washington, Oregon and California, and the species is listed as threatened under the U.S. Endangered Species Act in those states. “Early on in our work, we noticed strong fluctuations in the numbers of marbled murrelets coming inland to nest, so this study was about trying to get to the bottom of those highs and lows,” Betts said. “We found the first evidence that ocean conditions combined with old-forest nesting habitat influence the murrelets’ long-term occupancy dynamics. In particular, we learned ocean conditions are a key driver of those dynamics.” The finding has potential key implications for forest policy in Oregon, where any state-owned site that goes two consecutive years without murrelet detection is classified as unoccupied and thus available for timber harvest. Rivers says: “Our data show that below-average ocean conditions might last for more than two successive years. That means there could be a scenario where sites on state lands that are suitable for breeding go unused for more than two years which, under current guidelines, would let them be considered available for harvest. Thus, murrelets might be missing from inland sites not because the forest is unsuitable for nesting, but because they have inadequate forage fish during the summer breeding season. That means it is critical that we consider factors that influence both marine food resources and terrestrial nesting habitat when considering how to recover murrelet populations.” View the full article
  3. Changes in climate and habitat on the breeding and non-breeding grounds of migratory birds are both playing an important part in driving their long-term population changes. A new study led by the Department of Biosciences at Durham University, published in the journal Diversity and Distributions, is the first large-scale assessment of how recent changes in both climate and land cover have impacted populations of migrating birds. Global declines in the numbers of individuals of many migratory species are thought to be caused by a combination of climate change and habitat loss on both their breeding and non-breeding grounds, as well as changes to areas they use to refuel whilst on migration. Understanding of which factors are key in causing recent declines, and in which areas changes are having most impact, remains poor. Using data on the long-term population trends of 61 short- and 39 long-distance European breeding migratory birds, the researchers related changes in climate and land cover across their breeding and non-breeding grounds over a 36-year period to their population trends. The study showed that populations of migratory birds were most affected by changes in climate on the European grounds where they stopped to breed but, in the areas that they migrate to after the breeding season, changes in land cover had the greater impact. The combined effects of changes in climate and land cover account for approximately 40% of the variation in the population trends of migratory birds, which means that other factors, such as changes in habitat quality, probably also have a substantial impact on population changes. Professor Stephen Willis, who led the study, said: “For years, people have suspected that climate and land cover changes are major drivers of population trends of migratory birds. Here we show, for the first time that for long distance migrants moving between Europe and Africa, it is a combination of European climate change and African land cover change that are key to the population declines of many such species over recent decades. “In the UK, we have seen major declines in many migratory bird species that come here to breed from their African wintering grounds. For example, the Turtle Dove has declined by 95% between 1992-2017, and the Nightingale has declined by 56% between 1995 – 2018.” Lead author, Dr Christine Howard added: “The relatively minor role of recent climate changes on African non-breeding grounds for long distance migrants was surprising but probably reflects the less extreme climatic changes there compared to Europe. The fact that a lot of variation in population trends remain unexplained in our study suggests that other factors, such as agricultural intensification, are probably also impacting populations, along with changes at migratory stopping points, including hunting.” The researchers say that to stop the declines of European migrant birds, an integrated approach must consider all processes affecting them across the different grounds they inhabit throughout the year. View the full article
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