Project

Ashy Plover

Pluvianellus socialis

Scope of the project

Most of the breeding distribution is subject to some kind of livestock exploitation. The nests, built on the ground, suffer a high risk of egg loss due to trampling. The Río Gallegos estuary is the most important site for the conservation of the species. In this context, unleashed dogs and pollution of the estuary are a threat to the survival of the plovers.

habitat and behavior

Coasts with low vegetation and good visibility in lagoons, lakes, rivers and even in the sea. During the breeding season it is found in the south of Santa Cruz, north of Tierra del Fuego and in the region of Magallanes in Chile. In the winter season it migrates to the northeast along the Atlantic coast, even reaching the south of the province of Buenos Aires.

feeding

It digs with its feet to search for macroinvertebrates in the sediment, which is an unprecedented behavior among shorebirds. It also forages in the manner of other birds: it picks up rocks and detritus with its beak like a stonecatcher, skims the water line like a sandpiper, and makes short runs like a plover.

reproduction

Pairs form during the spring. They lay 1 or 2 eggs in a simple nest, which is usually a natural cavity and/or excavated in the coastal sediment lined with small stones. Often among the rocks to protect it from the wind and favor the crypsis of eggs, chicks and adults. Both parents take care of the chicks until they become independent.

curiosity

1) It is not a Plover! Paradoxically, the Cory's Plover is closely related to the Antarctic Pigeons. In fact, two fossils were discovered in Australia and New Zealand that suggest that both families are evolutionary relicts of a group that was more diverse millions of years ago.
2) The species was discovered in Tierra del Fuego in the 1840s, however it already had a name for the local Selk'nam people: Toish-te.

context

Project Ashy Plover

The Cory’s Plover is one of the most charismatic species of Southern Patagonia. It is one of the most sought after species by birders, but it is also a mystery. Very little known, with scarce and punctual information, without exhaustive works that allow us to know it in depth, either its ecology or the state of its populations. The Patagonia Program has been interested in this species since its inception, monitoring its populations, as well as other shorebird species. Although until a few years ago we did not carry out specific work focused on the species, since 2010 we have collected extremely important information to generate a baseline that we are currently beginning to take advantage of, with joint research and management strategies to know the real conservation status, the impact of the proposed threats and, above all, to test management actions that allow us to favor the conservation status if they are necessary to apply.

patagonia in action program

Lines of research

Determinants of Cory's Plover distribution from the perspective of trophic availability complemented by spatial analysis of citizen science records.

Responsible

John M. Krapovickas

State

Completed

Target

The overall objective of this line of research is to understand the distribution of the Cory's Plover through resources and ecological niche determinants at two different spatial scales. In particular, we seek to generate a model based on citizen science data and satellite imagery that allows predicting the potential distribution of the Ashy Plover. Also, to compare the trophic availability between a site with records of Cory's Plover, such as the Strobel Lake plateau, with another site without records, such as the Buenos Aires Lake plateau (ecologically similar and only 150 km to the north).

methodology

Data were obtained from lists uploaded by birders to the eBird citizen science platform contained within the range of the Ashy Plover in the period 2010-2021. Specifically, we used the EBD(eBird Basic Dataset) and SED(Sampling Event Dataset) products to obtain both lists that detected plovers and those that did not. On the other hand, we used satellite images (MODIS MCD v006), with a global resolution of 500 m, to calculate the percent ground cover around the locality of each list. We did this following the soil classification system proposed by the University of Maryland. Then, under the hypothesis that potential habitat for plovers exists at sites where it was not recorded, we used a species distribution model to predict their encounter rate as a function of land cover throughout their range. To characterize trophic availability we collected sediment cores (i.e. samples) from 34 ponds between January and February 2021 and 2022. In the Strobel Lake plateau eleven lagoons with presence of Cory's Plover and twelve lagoons without presence. On the Lake Buenos Aires plateau eleven lagoons with similar characteristics to the 22 surveyed on the Lake Strobel plateau. To make the sampling sites comparable, samples were taken immediately adjacent to the feeding site of plovers or other shorebirds (e.g., sandpipers of the genus Calidris spp. and plovers of the genera Zonibyx sp. and/or Anarhynchus sp.). These samples were sieved in situ and the macroinvertebrates found were preserved in 70% alcohol where, once in the laboratory, they were identified under binocular magnification. Once the database was formed, and with the hypothesis that the trophic availability is determinant for the distribution, we performed a three-part analysis: 1) first a multivariate analysis to evaluate how the ponds are ordered according to the taxa surveyed; 2) we calculated Shannon and Simpson diversity indices for each group of ponds; and 3) we elaborated univariate models to compare the means of abundance and taxonomic richness among the groups of ponds.

SCOPE AREA

The study area covered the entire extensive geographic distribution of the Cory's Plover, spanning more than 2000 km north-south and covering diverse environments from the Andes to the Atlantic coast. In its extension of approximately 100,000 ^km2 it partially includes five Argentine provinces (Tierra del Fuego, Santa Cruz, Chubut, Río Negro and Buenos Aires) and the region of Magallanes, in Chile. At the phytogeographic level, it stands out for its diversity, covering two regions, three domains, six phytogeographic provinces and thirteen vegetation units. However, the habitat suitable for the Plover in this huge territory is distributed in a restricted way, only some coasts (of lakes, lagoons, rivers, streams or even the sea) would be suitable to host the species.

Collaborators

- Dr. Luciana Raquel Musmeci - Laboratory of Wetlands used by Migratory Shorebirds (CCT-CONICET, CENPAT).
- Dr. María Sol Porcel - Limnology Laboratory of the Institute of Genetics, Ecology and Evolution (IEGEBA-CONICET) of the FCEN, University of Buenos Aires.
- Dr. Alejandro Gatto - Center for the Study of Marine Systems (CCT-CONICET, CENPAT).
- Dr. Alejandra Patricia Pérez - Photobiology Laboratory of INIBIOMA-CONICET and Universidad del Comahue.

results and progress

The results of this project can be found in the thesis of Juan M. Krapovickas defended in 2023. Specifically, we obtained a spatial model of encounter rate revealed that the presence of the Cory's Plover is associated with grasslands, water bodies, bare ground and elevated places. In addition, the working hypothesis was corroborated since it was found that potential habitat exists on the plateaus of Chenqueniyen (Río Negro) and Lago Buenos Aires (Santa Cruz), sites where it was not recorded before, which are 125 and 780 km respectively from the Strobel Lake plateau (northern end of the breeding range). This result indicates that there are underlying processes that modulate the distribution at other spatial and/or historical scales. The lagoons inhabited by the Cory's Plovers, at the northwestern end of the breeding range, are characterized by a higher diversity and abundance of macroinvertebrates. In addition, they possess distinctive taxa such as Trichoptera, Bivalvia, Bryozoa, Diptera and Ostracoda. These differences in abundance were significant when comparing lagoons with and without plovers within the Strobel Lake plateau, but were not significant when comparing the Strobel Lake plateau (with and without plovers) with those of Lake Buenos Aires (outside the usual range of the Cory's Plover). Higher values of organic matter and intermediate grain size were positively correlated with higher diversity and abundance of macroinvertebrates. Based on these results, the hypothesis that trophic availability is a determinant for the distribution of the plover in the northwestern part of its reproductive range is corroborated.

Improving reproductive success in the Ashy Plover.

Responsible

Technical Team

State

Active

Target

The objective of this line of research and management is to develop a management plan to maximize the reproductive success of the Ashy Plover in the high altitude plateaus of western Santa Cruz, to generate information on its reproductive biology, habitat use, trophic ecology, and movements. We have six specific objectives based on existing information, and especially on the lack of this information. The first is to identify the main breeding sites in the northwestern part of its distribution and to detect breeding events. Then, as a second objective, we want to evaluate the effect of closures for predators and large herbivores on the survival of eggs and chicks in nests. The third objective is to study the recruitment of juveniles, mainly to try to understand the factors that affect the mortality of chicks and juveniles after they leave the nest. On the other hand, we also seek to study aspects of reproductive biology and habitat use, as well as demographic parameters of importance, and as a fifth objective to study migratory behavior and seasonal movements. Finally, we seek to establish a guardian system for the nesting sites of the Cory's Plover.

methodology

Between October and March, that is, during the entire breeding season, the team of technicians and volunteers census shorebirds and waterfowl in the more than 350 lagoons that make up the Strobel Lake, La Siberia and Mata Amarilla plateaus. During this period, monthly censuses are also conducted on the shores of Lago Cardiel in search of Cory's Plovers. After the detection of pairs and individuals, enclosures are installed to protect the nests against terrestrial and aerial predators, as well as to prevent the loss of eggs and chicks by trampling of large herbivores. For this purpose, circular corrals of galvanized mesh (three meters in diameter by one and a half meters high) were installed around the nests of the Cory's Plover. These pens were covered with plastic mesh and equipped with a camera trap. Nesting pairs are also identified and monitored to know the reproductive success of their nests (both those in which the protections are installed and those in which they are not). We also record the presence of potential predators such as gulls, dogs, foxes, armadillos, ferrets and skunks, as well as potential nest trampling agents such as cows, sheep, horses, guanacos and people. To learn about aspects of the ecology and reproductive biology, focal observations and daily monitoring of the nests found were carried out. These observations were used to collect information on the size of the clutch, the incubation time of the eggs, the rate at which the parents feed their chicks and the time spent in the nest. Census data are used to estimate the number of adults on the plateaus (capture per unit effort) and individuals are banded to estimate long-term demographic parameters (capture-marking and recapture). Also, for the study of migrations and movements, adults and juveniles are equipped with PTT and GSM-GPS satellite trackers. Finally, as a conservation action we work with a team of guardians, consisting of at least one technician and one volunteer who are responsible for protecting nests from predation and trampling, monitor the population and use of space, install and supervise closures on nesting sites, and make observations of reproductive behavior.

Scope area

The study was conducted in the province of Santa Cruz, specifically in the thaw lagoon system of the Strobel Lake, Siberia and Mata Amarilla plateaus.

partners

- Shorebird Conservation Initiative, International Conservation Fund of Canada (ICFC).

results and progress

In the first season of work in 2023-2024 they made 29 records of Cory's Plover in 23 lagoons, detecting 83 adults, four incubating nests, 11 chicks and 11 juveniles, with courtships observed in two lagoons and Cardiel Lake. Two successful closures of 12 and 24 days were installed, with 72 hours of focal observations in 16 days, and the installation protocol was perfected. Ten nests were found (nine in Lago Strobel and one in Lago Cardiel), four in incubation produced chicks, and two nests had double chicks; in one closed nest possible predators were observed (Red Fox, European Hare and Kittiwake). The average feeding rate is one event every 9 minutes and 53 seconds and parent replacement incubating every 70 minutes, with closures affecting the absence of parents; 13 individuals were banded, creating a morphological database and the natal dispersal of the species was recorded. PTT and GSM-GPS equipment is expected to be deployed in spring 2024. In 24 days of monitoring, no large herbivores were observed near the nests, attributed to the scaring effect of the guardians, which also helps to collect behavioral observations.

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