Robert Clemens

Many shorebird populations are declining throughout the world, concurrent with declines and degradation of wetland habitats. Such declines necessitate a more consistent approach towards conserving habitats used by shorebird populations. Individuals of many shorebird species congregate in specific areas during their non-breeding season. Worldwide, non-breeding areas are designated as ‘important’ for shorebird conservation based primarily on the abundance of birds found in an area. However, the boundaries of any area are often defined with incomplete information regarding how shorebirds use that habitat. This paper discusses examples in Australia where improved knowledge of shorebird habitat use led to the identification of very different boundaries of important shorebird areas than those identified originally. We highlight how simple questioning of those who count shorebirds in an area, led to an improved understanding of which areas were apparently used by the same local population of non-breeding shorebirds. Subsequent analysis of available count, recapture and/or home range data of particular shorebird species is needed to verify expert opinion regarding most of these boundaries. We review how enhanced boundaries improve the ability of shorebird monitoring to detect population changes; allow management of shorebird habitats at relevant spatial scales; and lead to appropriate designations of important areas. While the kinds of approaches to boundary setting described here are not new, they are not consistently applied worldwide. We suggest additional guidelines to those produced under the Ramsar Convention in regard to designating important areas. We also call for more studies on the movements of migratory shorebirds during the non-breeding season to direct more consistent boundary setting around important non-breeding habitats used by local populations of migratory shorebirds.

"This paper provides an overview of the Australasian Wader Studies Group’s Population Monitoring Program (PMP) over the last 25 years at sites around Australia and comments on its ability to monitor long-term population trends in several species. The PMP provides the only comprehensive long term data set on shorebird numbers available to planners and government agencies. In this analysis, some of the shorebird count data collected as part of the PMP have been used to describe population trends for selected migratory wader species found in southern Australia. Results highlight the declining population trend for Curlew Sandpiper Charidris ferruguinea and suggest
declining trends for several other species. The importance of identifying the underlying demographic causes of these trends is emphasised. The need to identify trends early is suggested as a high priority given the habitat loss and other changes occurring in the flyway. Increasing the sensitivity of the PMP counts and addressing other shortcomings of the program require the development of a more robust and comprehensive monitoring design. Some recommendations are made for a National Shorebird Monitoring project."

Evidence of long-term declines in migratory shorebird populations is reported at two areas in north-east Tasmania. In north-east Tasmania, both George Town Reserve and Cape Portland have featured in National Wader Counts since 1981, although observations go back to the early 1970’s. Compared with the extreme north-west of Tasmania and with many mainland study sites, wader numbers in north-east Tasmania are never large, which makes for relatively easier counting. At George Town, count data indicate long-term population declines from 1974 to 2011 in Eastern Curlew, (Numenius madagascariensis), Ruddy Turnstone (Arenaria interpres), Curlew Sandpiper (Calidris ferruginea), and Bar-tailed Godwit (Limosa lapponica). George Town has also seen a decrease in the number of migratory shorebird species recorded each year, a drop on average from nine to seven, while Cape Portland has seen a larger drop in migratory shorebird species richness from eleven to six. Cape Portland has also experienced long-term declines from 1981 to 2011 in Ruddy Turnstone and Curlew Sandpiper. The reduction in species richness in both areas relates to historically uncommon species no longer being recorded such as Red Knot (Calidris canutus), Lesser Sand Plover (Charadrius mongolus), Greater Sand Plover (Charadrius leschenaultia), Grey-tailed Tattler (Tringa brevipes), Terek Sandpiper (Xenus cinereus) and Grey Plover (Pluvialis squatarola). Trends derived from these two north-east Tasmanian areas are similar to those being reported more widely in Australia, with growing numbers of migratory shorebirds showing evidence of long-term population declines. Threats to the foraging areas of both study sites, which have the potential to compromise their
viability, are outlined. The volume of data available from these areas will allow for more detailed analyses in future.

"Corner Inlet, Victoria, provides habitat for one of the largest and most diverse assemblages of shorebirds in southern Australia. Systematic counting commenced in 1981 and has continued, uninterrupted, to the present (2011). Standardised counts, along fixed boat routes, indicate that numbers in summer of all species combined have declined by 23% over the 30 year count period, from typically 35-40,000 in the earlier years to 25-30,000 in recent times. Ten species – Grey Plover Pluvialis squatarola, Ruddy Turnstone Arenaria interpres, Eastern Curlew Numenius madagascariensis, Red Knot Calidris canutus, Great Knot Calidris tenuirostris, Curlew Sandpiper Calidris ferruginea, Sharp-tailed Sandpiper Calidus acuminata, Common Greenshank Tringa nebularia, Greater Sand Plover Charadrius leschenaulti, and Lesser Sand Plover C. mongolus - have declined, while Sooty
Oystercatcher Haematopus fuliginosus, has increased. Numbers of five other migratory species –Bar-tailed Godwit Limosa lapponica, Whimbrel Numenius phaepus, Red-necked Stint Calidris ruficollis, Sanderling C. alba and Double-banded Plover Charadrius bicinctus and one resident, species, Australian Pied Oystercatcher Haematopus longirostris – have not shown any significant change. Estimated declines in the abundance of
individual species ranged from 47% to 95%. In contrast there was a significant increase in Sooty Oystercatchers of between 1.5 fold (winter) and 3.5 fold (summer). Numbers counted varied widely between years, most likely due to a combination of annual variation in demographic parameters, and possibly detection rates. The cause of longterm changes in abundance at Corner Inlet is not certain, but habitat destruction in staging areas, notably the Yellow Sea regions of China and Korea, is suggested as the main contributor with related changes in adult survival
rates a more likely mechanism than changes in breeding success. Interestingly, declines in several species were most pronounced over one or two years. This study emphasises the benefit of using the same route and observers over long periods to identify trends in abundance."

Shorebirds are one of the most well-monitored taxa in Australia. In this paper, we review the spatial and temporal coverage of the Australian shorebird monitoring count data currently administered by BirdLife Australia, and comment on the subset of those data likely to be of immediate use for comprehensive trend analysis. Of the 253 shorebird areas known in Australia seventeen in the southern half of Australia had consistent survey coverage over the last 30 years, with summer counts available in over 80% of those years, and with each area holding nationally significant numbers of some shorebird species. Similarly consistent data were available for eight additional shorebird areas, but these generally held fewer birds. Another 21 shorebird areas with nationally important numbers of shorebirds had 15 to 30 years of data with some variation in spatial coverage or changes in methods over time. Our review suggests that Australian shorebird monitoring data are of sufficiently high quality and spatial coverage to permit robust analysis of shorebird population trends across much of Australia.

Global biodiversity continues to decline rapidly, and addressing this situation requires an understanding of both the problems and the solutions. This understanding is urgently required for animals occupying wetlands, among the most threatened of all habitats globally. In this thesis I focus on the ecology and conservation of shorebirds, a group comprising many threatened and declining species dependent on wetlands throughout much of their annual cycle. I focus on threats operating within Australia, where wetland loss and degradation continues due to human activity. Non-migratory shorebird species that travel widely across Australia’s inland wetlands have been reported as declining in eastern Australia, but a national assessment is lacking. Migratory shorebird species that visit Australia from breeding grounds overseas appear to be declining most due to factors beyond Australia’s borders, but it is not clear if threats located in Australia are exacerbating these declines. I make the most of the rich data available on shorebirds in Australia to address these knowledge gaps, in the hopes of better targeting shorebird conservation actions in Australia.
In chapter one I introduce the importance of conserving migratory and highly mobile species. I then review how pulses in resource availability such as those exemplified by Australia’s ephemeral wetlands impact wildlife populations. I also provide an overview of shorebird conservation in Australia. These introductions provide the theoretical underpinning for the work presented later, and highlight the challenges inherent in understanding where and when highly mobile species such as shorebirds have been impacted.
In chapter two I show the benefits of applying a consistent approach to setting boundaries around areas used by migratory shorebirds during the non-breeding season. One of the first steps in identifying where conservation actions are needed for highly mobile species is defining the boundaries of management units where actions can be targeted, and which define the optimal scale for monitoring. I achieved this step by using expert knowledge to define the extent of area being used by the same local population of non-breeding shorebirds. These improved boundaries were at times very different to boundaries identified originally.
In chapter three I analyse available Australian shorebird count data from many areas to determine if spatial variation in shorebird trends relates to local threats. I confirm Australia wide declines in a number of shorebird species, and add a few more to the list of shorebird species showing continental scale declines. I further show that declines are often greater in the south, but find substantial interspecific variation in trends with both latitude and longitude. This suggests large scale patterns in the declines are not explained by local factors. For resident shorebirds I find rates of decline greater at non-tidal wetlands threatened by inappropriate water levels, while local threats do not appear to explain rates of decline in migrants. Results are consistent with other studies indicating wetland degradation in Australia has impacted resident shorebirds, but migrants have been impacted most by factors outside Australia. Heterogeneous trends in migrants do suggest, however, places where habitat management in Australia might have the largest positive impact.
In chapter four I explore whether predictive modelling can improve our understanding of shorebird species’ distributions over time and space in a remote continent characterized by many sporadically available ephemeral wetlands. I view this as a critical first step in understanding the degree to which degradation of Australia’s inland wetlands has impacted shorebird populations. Results indicate that our predictions perform poorly at fine temporal and spatial scales, but they do capture long-term changes in abundance as well as average distribution patterns for 12 species. The models also deliver improved estimates of total population size, and indicate that at times some species experience far greater continental reductions in area of suitable habitat than other species.
In chapter five I investigate whether inland regional or continental wetland degradation has impacted three species of migratory shorebird at three sites in southern Australia which use both coastal and inland wetland habitats. Results confirm that variation in abundance is somewhat explained by inland wetland conditions for Curlew Sandpiper, Sharp-tailed Sandpiper and Red-necked Stint. Juvenile ratios are also explained partially by inland wetland conditions suggesting young birds are even more likely to visit interior wetlands than adults. A small but significant amount of the variation in apparent survival in these species is also explained by inland wetland conditions. Results for Curlew Sandpiper suggest that inland wetland condition may be interacting with deteriorating conditions at stop-over locations resulting in a growing importance of inland wetland conditions for annual survival of this now critically endangered shorebird. These results point toward potential benefits of managing inland wetlands for shorebirds.
In the last chapter I review how the findings presented in this thesis fit within a growing understanding of shorebird population ecology, and how these findings point toward more targeted conservation actions. I further explore the limitations of these studies, and highlight where further research would be most fruitful.