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The Spoon-billed Sandpiper Calidris pygmaea is a ‘Critically Endangered’ migratory shorebird. The species faces an array of threats in its non-breeding range, making conservation intervention essential. However, conservation efforts are reliant on identifying the species’ key stopover and wintering sites. Using Maximum Entropy models, we predicted Spoon-billed Sandpiper distribution across the non-breeding range, using data from recent field surveys and satellite tracking. Model outputs suggest only a limited number of stopover sites are suitable for migrating birds, with sites in the Yellow Sea and on the Jiangsu coast in China highlighted as particularly important. All the previously known core wintering sites were identified by the model including the Ganges-Brahmaputra Delta, Nan Thar Island and the Gulf of Mottama. In addition, the model highlighted sites subsequently found to be occupied, and pinpointed potential new sites meriting investigation, notably on Borneo and Sulawesi, and in parts of India and the Philippines. A comparison between the areas identified as most likely to be occupied and protected areas showed that very few locations are covered by conservation designations. Known sites must be managed for conservation as a priority, and potential new sites should be surveyed as soon as is feasible to assess occupancy status. Site protection should take place in concert with conservation interventions including habitat management, discouraging hunting, and fostering alternative livelihoods.
The catastrophic declines of three species of ‘Critically Endangered’ Gyps vultures in South Asia were caused by unintentional poisoning by the non-steroidal anti-inflammatory drug (NSAID) diclofenac. Despite a ban on its veterinary use in 2006 (India, Nepal, Pakistan) and 2010 (Bangladesh), residues of diclofenac have continued to be found in cattle carcasses and in dead wild vultures. Another NSAID, meloxicam, has been shown to be safe to vultures. From 2012 to 2018, we undertook covert surveys of pharmacies in India, Nepal and Bangladesh to investigate the availability and prevalence of NSAIDs for the treatment of livestock. The purpose of the study was to establish whether diclofenac continued to be sold for veterinary use, whether the availability of meloxicam had increased and to determine which other veterinary NSAIDs were available. The availability of diclofenac declined in all three countries, virtually disappearing from pharmacies in Nepal and Bangladesh, highlighting the advances made in these two countries to reduce this threat to vultures. In India, diclofenac still accounted for 10–46% of all NSAIDs offered for sale for livestock treatment in 2017, suggesting weak enforcement of existing regulations and a continued high risk to vultures. Availability of meloxicam increased in all countries and was the most common veterinary NSAID in Nepal (89.9% in 2017). Although the most widely available NSAID in India in 2017, meloxicam accounted for only 32% of products offered for sale. In Bangladesh, meloxicam was less commonly available than the vulture-toxic NSAID ketoprofen (28% and 66%, respectively, in 2018), despite the partial government ban on ketoprofen in 2016. Eleven different NSAIDs were recorded, several of which are known or suspected to be toxic to vultures. Conservation priorities should include awareness raising, stricter implementation of current bans, bans on other vulture-toxic veterinary NSAIDs, especially aceclofenac and nimesulide, and safety-testing of other NSAIDs on Gyps vultures to identify safe and toxic drugs.
Populations of Critically Endangered White-rumped Gyps bengalensis and Slender-billed G. tenuirostris Vultures in Nepal declined rapidly during the 2000s, almost certainly because of the effects of the use in livestock of the non-steroidal anti-inflammatory drug diclofenac, which is nephrotoxic to Gyps vultures. In 2006, veterinary use of diclofenac was banned in Nepal and this was followed by the gradual implementation, over most of the geographical range of the two vulture species in Nepal, of a Vulture Safe Zone (VSZ) programme to advocate vulture conservation, raise awareness about diclofenac, provide vultures with NSAID-free food and encourage the veterinary use in livestock of a vulture-safe alternative NSAID (meloxicam). We report the results of long-term monitoring of vulture populations in Nepal before and after this programme was implemented, by means of road transects. Piecewise regression analysis of the count data indicated that a rapid decline of the White-rumped Vulture population from 2002 up to about 2013 gave way to a partial recovery between about 2013 and 2018. More limited data for the Slender-billed Vulture indicated that a rapid decline also gave way to partial recovery from about 2012 onwards. The rates at which populations were increasing in the 2010s exceeded the upper end of the range of increase rates expected in a closed population under optimal conditions. The possibility that immigration from India is contributing to the changes cannot be excluded. We present evidence from open and undercover pharmacy surveys that the VSZ programme had apparently become effective in reducing the availability of diclofenac in a large part of the range of these species in Nepal by about 2011. Hence, community-based advocacy and awareness-raising actions, and possibly also provisioning of safe food, may have made an important contribution to vulture conservation by augmenting the effects of changes in the regulation of toxic veterinary drugs.
The spoon-billed sandpiper Calidris pygmaea, a migratory Arctic-breeding shorebird, is one of the rarest birds and its population has declined since the 1970s. We surveyed its most important known wintering area in the Upper Gulf of Mottama in Myanmar to estimate recent (2009–2016) changes in its numbers there. The total number of small shorebirds present in the Upper Gulf was counted and the proportion of them that were spoon-billed sandpipers was estimated from sample scans. These two quantities were multiplied together to give the estimated number of spoon-billed sandpipers in each of 4 years. Total numbers of combined small shorebird species tripled from 21,000 to 63,000 between 2009 and 2016, coincident with efforts to reduce hunting pressure on waterbirds. However, the proportion of small shorebirds that were spoon-billed sandpipers declined and their estimated absolute numbers fell by about half, from 244 to 112 individuals. It is probable that loss of intertidal habitat and shorebird hunting elsewhere on the migration route of the spoon-billed sandpipers wintering at Mottama is causing a continued decline, although this is occurring at a less rapid rate than that recorded from Arctic Russia before 2010. The number of spoon-billed sandpipers wintering on the Upper Gulf of Mottama remains the highest single-site total for this species from any known wintering site. Preventing resurgence of illegal shorebird hunting and ensuring long-term protection of the intertidal feeding habitats and roost sites in the Gulf are high priorities if extinction of this species is to be averted.
Populations of the White-rumped Vulture Gyps bengalensis, Indian Vulture G. indicus and Slender-billed Vulture G. tenuirostris declined rapidly during the mid-1990s all over their ranges in the Indian subcontinent because of poisoning due to veterinary use of the non-steroidal anti-inflammatory drug diclofenac. This paper reports results from the latest in a series of road transect surveys conducted across northern, central, western and north-eastern India since the early 1990s. Results from the seven comparable surveys now available were analysed to estimate recent population trends. Populations of all three species of vulture remained at a low level. The previously rapid decline of White-rumped Vulture has slowed and may have reversed since the ban on veterinary use of diclofenac in India in 2006. A few thousand of this species, possibly up to the low tens of thousands, remained in India in 2015. The population of Indian Vulture continued to decline, though probably at a much slower rate than in the 1990s. This remains the most numerous of the three species in India with about 12,000 individuals in 2015 and a confidence interval ranging from a few thousands to a few tens of thousands. The trend in the rarest species, Slender-billed Vulture, which probably numbers not much more than 1,000 individuals in India, cannot be determined reliably.
The spoon-billed sandpiper Calidris pygmaea is a Critically Endangered shorebird that breeds in the Russian arctic and winters in coastal and estuarine habitats in South-east Asia. We report the first formal estimate of its global population size, combining a mark–resighting estimate of the number of leg-flagged individuals alive in autumn 2014 with an estimate of the proportion of birds with flags from scan surveys conducted during the same period at a migration stop-over site on the Jiangsu coast of China. We estimate that the world breeding population of spoon-billed sandpipers in 2014 was 210–228 pairs and the post-breeding population of all age classes combined was 661–718 individuals. This and related methods have considerable potential for surveillance of the population size of other globally threatened species, especially widely dispersed long-distance migrants.
The Upper Mustang region of Nepal holds important breeding populations of Himalayan Griffon Gyps himalayensis. Despite this species being considered ‘Least Concern’ on the IUCN Red List, the population in Upper Mustang had declined substantially in the early to mid-2000s. During that period, the non-steroidal anti-inflammatory drug diclofenac was commonly used to treat illness and injury in domesticated ungulates throughout Nepal. The timing and magnitude of declines in Himalayan Griffon in Upper Mustang resemble the declines in resident populations of the ‘Critically Endangered’ White-rumped Vulture Gyps bengalensis and Slender-billed Vulture Gyps tenuirostris in Nepal, both of which are also known to be highly sensitive to diclofenac. Since 2006, the veterinary use of diclofenac has been banned in Nepal to prevent further vulture declines. In this paper, we analyse the population trend in Himalayan Griffon in Upper Mustang between 2002 and 2014 and show a partial recovery. We conclude that the decline is now occurring at a slower rate than previously observed and immigration from areas where diclofenac was either not or rarely used the probable explanation for the recovery observed.
The collapse of South Asia's Gyps vulture populations is attributable to the veterinary use of the non-steroidal anti-inflammatory drug (NSAID) diclofenac. Vultures died after feeding on carcasses of recently-medicated animals. The governments of India, Nepal and Pakistan banned the veterinary use of diclofenac in 2006. We analysed results of 62 necropsies and 48 NSAID assays of liver and/or kidney for vultures of five species found dead in India between 2000 and 2012. Visceral gout and diclofenac were detected in vultures from nine states and three species: Gyps bengalensis, Gyps indicus and Gyps himalayensis. Visceral gout was found in every vulture carcass in which a measurable level of diclofenac was detected. Meloxicam, an NSAID of low toxicity to vultures, was found in two vultures and nimesulide in five vultures. Nimesulide at elevated tissue concentrations was associated with visceral gout in four of these cases, always without diclofenac, suggesting that nimesulide may have similar toxic effects to those of diclofenac. Residues of meloxicam on its own were never associated with visceral gout. The proportion of Gyps vultures found dead in the wild in India with measurable levels of diclofenac in their tissues showed a modest and non-significant decline since the ban on the veterinary use of diclofenac. The prevalence of visceral gout declined less, probably because some cases of visceral gout from 2008 onwards were associated with nimesulide rather than diclofenac. Veterinary use of nimesulide is a potential threat to the recovery of vulture populations.
In the first part of the book, we examined the impacts of climate change on bird populations. We found good evidence that significant changes have occurred in the timing of seasonal events within the annual cycle of birds (Chapter 2). In recent decades, both spring arrival of migratory species and egg-laying dates, as measured for the average individual in a population, have advanced consistently by some 2 days per decade across temperate and boreal latitudes. Phenological changes affecting the timing of the end of the breeding season, and autumn departure dates of migrants have varied much more between species, depending on migration, moult and breeding strategies. A wide range of correlative analyses, supported by a small number of studies of underlying mechanisms, have demonstrated that many of these changes are a consequence of warming. Recent climate change has therefore altered the seasonal pattern of avian life cycles. Although there is currently insufficient monitoring of birds in tropical areas to track their long-term phenological responses to climate change, the studies which have been conducted suggest that here, changes in precipitation, and not temperature, are likely to be the main determinant of the timing of commencement of the breeding season and the movement of individuals. Trends in tropical bird phenology are therefore likely to be related primarily to changes in rainfall patterns.
Having described the impacts that climate change has already had upon birds, their populations, distributions and communities, in this second part of the book, we look now at what can be done to reduce the negative impacts of current and future climate changes on birds. The first stage in attempting to do this is to predict what the consequences of future climate change will be for the conservation status of wild species and populations. Although there are many impacts of climate change which have been documented, few clearly demonstrate a current and urgent threat to particular populations or species. For most species, it is not the climate change which has occurred so far that is the problem, but the magnitude of climate change to come. In this chapter, we attempt to quantify the likely size of that future problem – how severe is the impact of climate change on birds likely to be?
This is not a simple question to answer. The foregoing chapters documented the complexity of the effects of climate and climatic change on reproductive and mortality rates of birds, which are the mechanisms by which climate affects their distribution and abundance. Given this complexity, it might be thought that any attempt to predict the effect of climate change on a bird species would require a detailed knowledge of how its demographic rates will be affected, in both the short and the long term. Such knowledge can certainly be very helpful as we shall see later in this chapter, but realistically, is only available for a handful of the 10 000 bird species on Earth. To make an assessment that will be widely applicable, we need to consider alternative approaches, which require less detailed information, to predicting the effects of climate change on bird species. Building on the role of climate in delimiting species’ distributions (Sections 1.8 and 5.2), the most widely used approach is to build a statistical model of geographical variation in the distribution or abundance of a species in relation to climatic and sometimes also to other environmental variables. The spatial association between a species and climate described by that model is then used to make future projections of the impact that climate change may have on that species’ distribution or abundance.
This book is about the impact of global climate change on birds, especially on their populations and conservation status, and what can be done about it. Birds are widespread in their distribution and occur in almost all environments. People enjoy watching them and many are easy to observe. As a result, they have long been studied by both amateur naturalists and professional scientists and they are amongst the best understood group of organisms. Data exist on the migration of birds from ringing (banding) studies and the direct observation of arriving and departing individuals, on their historical distribution from museum specimens, archaeology, literary and other sources, and on the timing and success of their breeding from nest recording that span many decades, or in the case of museum specimens, over a century. More recently, quantitative counting and mapping techniques have provided up to 50 years of standardised population and distribution data collection (Møller & Fiedler 2010). The internet is now being used to collect millions of sightings from bird watchers every year, whilst recent technological advances allow almost real-time tracking of migrating birds. These data provide an unparalleled opportunity first to understand the relationship between climate and species distributions and populations, and second to document changes in those distributions and populations occurring as a result of climatic change. Critically reviewing and documenting these kinds of evidence and what they tell us about the impacts of climate change on birds is one of the main purposes of this book, covered in Part 1.
Unfortunately, popular as they are, many bird species and populations are under threat. Of the 10 064 bird species identified around the world, some 13% are regarded as threatened by extinction within the next 100 years. Another 880 species are near-threatened (BirdLife International 2012a). Populations of habitat-specialists and shorebirds are in particular decline (Butchart et al. 2010). The threat of extinction which these species face is a real one; 103 species have been lost forever during the last 200 years. There is an urgent need for effective bird conservation to halt these trends. Whilst there have been significant conservation successes, these have only slowed, rather than halted, global rates of biodiversity loss (Butchart et al. 2010; Hoffman et al. 2010). Conservationists are winning occasional battles, but seem to be losing the war.
Climate change is anticipated to result in species shifting their distribution to higher latitudes and altitudes (Chapter 6), as has already been observed (Chapter 5). Changes to habitats, and the abundance of food organisms, predators, competitors, parasites and diseases, and the direct effects of climate will alter species’ demographic rates and abundance (Chapters 3 and 4). In parts of the range where population density increases, this is likely to result in an increasing number of dispersing individuals being available to colonise areas of habitat beyond the current range margin. At the retreating range margin, conditions are likely to become increasingly unfavourable, resulting in reduced fecundity and/or survival. Initially, as population density declines, negative effects of climatic change on a particular demographic rate may be at least partially compensated for by density-dependent improvements in other rates. The population in this part of the range may then stabilise at a lower level for some time. However, progressive change will eventually cause population declines, fragmentation of the distribution, local extinctions and finally loss of range. Between the expanding and retreating margins, the same mechanisms may lead to shifts in the distribution of areas with high population density, and changes to the composition of communities (Chapter 5).
Observations of impacts of climate change, and concerns over the impacts projected to come, have stimulated increasingly detailed thinking about what conservationists can do to counter negative impacts through what is termed climate change adaptation: interventions to reduce the vulnerability of species and their habitats to actual or expected climate change effects. Recent advances in conservation science have provided an increased understanding of the precise requirements of species and the impacts upon them of threats such as habitat loss and degradation, overexploitation, persecution and pollution, all driven by expanding human populations and their increased demands for food, recreation and commodities. This understanding has underpinned some successful conservation programmes that have reversed population declines and range losses of some species. We therefore start this chapter with a summary of the tools that conservationists have found to be effective in countering these threats to birds, before considering how they may be adapted for use in the face of climate change.
As we explained in Chapter 1, environmental variables, including the weather and climate, can only influence bird populations if they alter demography: the reproductive or mortality rates and, for the subdivided parts of a closed population, immigration and emigration as well. In the previous chapter we discussed the effects of phenological mismatch on bird populations, but that is just one of the ways in which climate change can have an impact on demography (Table 4.1). These other mechanisms are the focus of this chapter. We will not restrict ourselves only to studies of climate change impacts, but also review the wider range of studies which have looked at the relationships between bird population processes and temperature, precipitation and other weather variables. Whilst many of these will really be examining the effects of annual variation in the weather (as opposed to long-term trends in climatic averages), they may still be useful in helping us understand the impact of climate change upon bird populations in the future.
Long-term studies are necessary in order to adequately describe how populations respond to annual fluctuations in the weather, and especially to see how population size is affected by longer-term changes, including recent climate change (which we regard as a long-term change in those weather variables, ideally over a minimum 30-year period, although many studies putatively demonstrating impacts of climate change span shorter periods). One of the longest such studies is that of the annual heronry census, coordinated by the BTO since 1928, which has been used to demonstrate the sensitivity of grey heron Ardea cinerea populations to cold winter weather (North 1979; Reynolds 1979). The impact of severe winters can be clearly seen leading to periodic population declines, but in response to a run of mild winters from the late 1980s to late 2000s, the population remained high and stable (Figure 4.1). Such large-scale population monitoring programmes are now widely established across Europe and North America, and often use the observations of amateur ornithologists, collected using standardised methods (e.g. Anders & Post 2006; Gregory et al. 2009; Moller & Fiedler 2010) to deliver large-scale monitoring for the production of robust population trend estimates (van Strien et al. 2001; North American Bird Conservation Initiative, US Committee 2011). However, for many species and countries elsewhere, these annual monitoring data do not exist, which is an obstacle to scientific understanding and effective conservation action (Amano & Sutherland 2013).
Preceding chapters have illustrated how temperature, precipitation and other climatic factors affect the breeding productivity, survival and abundance of individual bird species through a variety of mechanisms. As a result, the geographical ranges of species can frequently be well described by the climate, as illustrated with reference to the red grouse in Chapter 1, although that descriptive ability does not show for certain whether the climate has a direct influence, an indirect influence or no real influence at all on species’ distributions (Gaston 2003). There are plenty of examples of biotic factors such as prey availability (Koenig & Haydock 1999; Banko et al. 2002), competition (Terborgh 1985; Emlen et al. 1986; Gross & Price 2000) and predation (Pienkowski 1984; Dekker 1989) being the main proximate factor limiting species’ ranges, but of course, the distribution of many of those other species may also be affected by climate. For example, the northern limit of the distribution of the red fox, which is thought to restrict the range of some wader species (e.g. Pienkowski 1984), is determined by resource (food) availability and therefore ultimately determined by climate (Hersteinsson & Macdonald 1994). The northern limit of Hume’s leaf warbler Phylloscopus humei which feeds on arthropods in tree canopies, is limited by cold temperature, as this causes leaf loss and therefore reduces food availability (Gross & Price 2000). Climate is therefore often regarded as the ultimate determinant of species’ distributions and abundance, even though the precise mechanisms causing the limitation may be unclear (Huntley et al. 2007).