Breeding habitats, phenology and size of a resident population of Two‐banded Plover (Charadrius falklandicus) at the northern edge of its distribution

Abstract

The central‐peripheral hypothesis states that the demographic performance of a species decreases from the centre to the edge of its range. Peripheral populations are often smaller and tend to occur under different and suboptimal conditions from those of core populations. Peripheral populations can also coexist during part of their annual cycle with populations from the core of the species’ range. Studies on peripheral populations are thus valuable for broadly understanding ecological and evolutionary processes. The Two‐banded Plover (TWBP, Charadrius falklandicus, Charadriidae) is an endemic South American shorebird that breeds in Argentine and Chilean Patagonia and migrates northward during the Austral winter. There are breeding records, however, from Lagoa do Peixe National Park in southern Brazil. In this study, we (i) mapped TWBP nests, (ii) characterised their reproductive biology and nesting habitats, (iii) colour‐marked birds and evaluated their seasonal occurrence patterns and (iv) estimated the size of the Brazilian population by combining supervised habitat classification analyses and generalised additive models. We estimated that the Brazilian population has 55 (95% CI: 44.1–66.6) breeding pairs and found that the length of their breeding season was roughly 5 months, spanning the Austral spring and summer. The population’s nesting habitat differed, and their apparent reproductive success was lower than that of core populations. Unlike more southerly populations, the results of our mark‐resighting efforts demonstrate that the Brazilian population is sedentary. Taken together, these results indicate that the Brazilian TWBP population seems geographically isolated from the species’ southernmost core populations, resulting in a heteropatric distribution. Furthermore, differences in nesting habitat and year‐round residency indicate that this peripheral population is ecologically distinct. The marked behavioural and ecological differences combined with the small population at the northern edge of the TWBP distribution support the central‐peripheral hypothesis in a Neotropical system.

Trends and population estimate of the threatened Buff-breasted SandpiperCalidris subruficolliswintering in coastal grasslands of southern Brazil

“…Stratoulias et al 2015). These bands have been previously used for saltmarsh habitat classification in southern Brazil (Nogueira and Costa 2003, Faria et al 2021). We used supervised classification models based on a maximum-likelihood algorithm to classify habitat types (i.e.…”

Updated bird list of Lagoa do Peixe National Park, one of the most important South American wetlands

“…Another group of species often displays the opposite pattern, coming from the southern parts of South America to escape from the harsh and cold weather conditions of the austral winter. They use LPNP as a stopover or foraging area during these times, as occurs for the Two-banded Plover Charadrius falklandicus Latham, 1790 and South American Tern Sterna hirundinacea Lesson, 1831 (Branco, 2003;Faria et al, 2021), despite some of them, as occurred with the Two-banded Plover, already being recorded breeding in the area (Faria et al, 2021). The opposed regimes of migration and displacement of these species avoid the extra competition for resources during the year since they often use the park in different periods: the northern species use the area during the austral spring and summer, meanwhile, the southern species come to the park during the fall and winter period in the southern hemisphere (Greenberg et al, 1994;Ahola et al, 2007).…”

Population estimates of shorebirds on the Atlantic Coast of southern South America generated from large-scale, simultaneous, volunteer-led surveys

“…Then, because no good remote sensing tools exist to differentiate among the habitats systematically, we visually classified each section as restinga , rocky beach, sandy beach, or ‘unsuitable’ (artificial buildings such as harbors/piers, industries, and cliffs). For the habitats with polygon-based surveys, we generated multispectral images with spectral bands 8, 4 and 3, as near infrared is efficient at differentiating among vegetation types as well as detecting exposed soil/water (Stratoulias et al 2015, Faria et al 2021). In addition, we created polygons bordering all estuaries and cities (e.g., areas with >10 ha of buildings and streets rather than simply areas within legal jurisdictional limits) along the coastline.…”