Factors influencing the abundance of wintering western snowy plovers at Crown Memorial State Beach

Survival during the nonbreeding season, when mortality from food shortages and raptor predation is highest, influences shorebird population growth. These selection pressures, as well as anthropogenic influences, can shape wintering shorebird habitat use patterns. The western snowy plover (Charadrius alexandrinus nivosus) is a small shorebird that uses sand-spits, dune-backed beaches, open areas around estuaries for foraging and roosting. The Pacific Coast population of western snowy plovers is listed as a federally threatened species and a California Species of Special Concern. Previous studies suggest humans, dogs and corvids are sources of disturbance to plovers on public beaches. During 2014 to 2019, these disturbance factors were examined at Robert W. Crown Memorial State Beach in Alameda, California. In decreasing order of impact, the beach using public, corvids, and dogs were found to be the major stressors to over wintering plovers. Both the public and corvids respectively, resulted in disturbance and avoidance behaviors by plovers nearly 40% of the time. In 2015, the District created the Plover Protection Zone (PPZ) by installing symbolic fencing, signage, and establishing a volunteer team to monitor plovers and educate the public. In 2016, the potential prey abundance within the plover protection zone and areas directly north and south were examined using core samples and sticky traps. Statistical analysis showed a significant difference in the amount of macro-invertebrate prey available in the area used by the plovers as compared to other locations. Habitat choice and prey availability are vital to wintering shorebird. During this study, the wintering population of western snowy plovers increased from six to over 54 individuals.

Slow and Steady: Gradual Drawdown of Private Wetlands Supports Shorebirds During Northbound Migration.

The Grasslands Ecological Area is the largest contiguous wetland complex in California's Central Valley and is a stronghold for hundreds of thousands of waterbirds. Primarily managed for waterfowl habitat and forage production, privately-owned seasonal wetlands in the Grassland Ecological Area are typically flooded in fall and dewatered the following spring in February and March. These wetlands support large populations of nonbreeding shorebirds and other waterbirds in winter. When the number of migratory shorebirds using the region peaks in mid-April, most wetlands have already been dewatered. The mismatch in the timing of available habitat and the habitat needs of migrating shorebirds contributes to the observed deficit of shorebird habitat in the Central Valley in spring. Working with private landowners, we developed and tested a wetland management practice designed to increase the amount of shallow water habitat available to shorebirds in April by delaying the drawdown and reducing water levels more slowly (gradual drawdown) relative to the traditional management practice. On average, we found that wetlands managed with gradual drawdown provided over twice as much shorebird habitat, contributing up to 26% of the overall shorebird habitat objective for the Central Valley. Wetlands managed with gradual drawdown supported up to 21 times more migratory shorebirds during peak migration and a greater number of shorebird species than traditionally-managed wetlands. Our results demonstrate the potential of working with private landowners to implement small changes in wetland management that can have a large impact in meeting regional conservation objectives for migratory shorebirds.

Distances walked by beach users and protecting shorebird habitat zones from disturbance

ABSTRACTHuman population growth along Australia’s coast is increasing development and recreation pressures on beaches and shorebirds. This study observed human recreation on 18 beaches on the far north coast of New South Wales in February and March 2019. The far north coast supports the largest numbers of beach-resident Australian Pied Oystercatchers Haematopus longirostris in the State. The most frequent activities observed were walking (29%), dog walking (21%) and swimming (16%). Walkers covered greater distances compared to other beach users. For beach walkers and dog walkers combined, the mean along shore distance walked from an access point was 809 m and the 95th percentile was 1990 m. Noting that human recreation disturbance is a major conservation threat to beach nesting birds and that pro-environmental behaviour is uncommon among beach users, large separation distances between beach access points and shorebird habitat zones are recommended to reduce human intrusions into those zones. This spatial zoning and passive human exclusion strategy can be applied to long and less-developed beaches.

Mapping foraging habitat for migratory shorebirds in their Australian non-breeding grounds and prioritising sites for conservation and management

Shorebird populations are declining worldwide as a result of the loss of the intertidal habitats upon which they depend. Conservation status is particularly dire for shorebirds on the East Asian–Australasian Flyway. While the flyway transects many international boundaries and involves numerous bilateral conservation agreements, management of remaining habitat at a local scale is imperative to conserving these species. Coastal habitat is affected by multiple anthropogenic stressors, including loss and degradation due to increasing demand for coastal land. In Australia, migration coincides with the summer holiday season when shorebirds are significantly impacted by human disturbance. Managers are frequently required to make trade-offs between wildlife conservation and anthropogenic land uses and when specific quantitative shorebird habitat data and mapping are absent, human interests will naturally take precedence. This paper demonstrates a method for mapping and prioritising management of shorebird non-breeding habitat using an Australian coastal site, the Richmond River estuary. Foraging habitat was surveyed and mapped using GIS with a range of attributes including habitat types, foraging values, disturbance levels and specific foraging distribution of each species. The results highlighted several important foraging areas that were impacted by disturbance and would require intervening management actions to reduce impacts on shorebirds. The GIS data created provide local managers with an effective tool to consider shorebird habitat in the decision-making process. This method could be replicated at other important shorebird habitat sites, leading to enhanced conservation of these declining species.