By: Arne Lesterhuis & Joaquín Aldabe
During early September 2021, six teams, including staff from WHSRN Executive Office, scattered throughout the Llanos de Moxos (or Beni Savannas), a vast area of natural grasslands and flooded savannas covering 120,000 km2 in northern Bolivia, to survey for Buff-breasted Sandpipers (Calidris subruficollis). Tracking studies in recent years, coordinated by Richard Lanctot, Alaska Shorebird Coordinator, United States Fish and Wildlife Service (USFWS) USFWS, revealed that Buff-breasted Sandpipers use a narrow migration corridor through these savannas during their southbound migration.
The only reliable shorebird data from the Llanos de Moxos came from the Barba Azul Nature Reserve (Barba Azul). Since 2014, annual monitoring by Asociacion Armonia has indicated that large numbers of Buff-breasted Sandpipers, Pectoral Sandpipers (Calidris melanotos), Upland Sandpipers (Bartramia longicauda) and to a lesser extent American Golden-Plover (Pluvialis dominica) use the savannas of Barba Azul during their southbound migration. Significant counts of the Buff-breasted Sandpiper, representing over 2.5% of the species global population, resulted in the designation of Barba Azul as a WHSRN site of Regional Importance, the first site in Bolivia. Based on the results of the tracking studies and this on-the-ground monitoring at Barba Azul, the Llanos de Moxos were believed to represent critical stopover habitat for the majority of the species’ population.
To further assess the potential importance of the Llanos de Moxos, Asociacion Armonia and WHSRN Executive Office collaborated on a simultaneous survey with multiple teams on the ground. Thanks to Manomet, Environment and Climate Change Canada (ECCC), and the USFWS, funds supported six teams monitoring a large area of the Llanos de Moxos. A survey protocol was developed based on surveys carried out in the Flint Hills, a WHSRN site of Hemispheric Importance in North America and key migration site of the Buff-breasted Sandpiper. The protocol consisted of point counts with a distance of 1 kilometer (km) between each point, along roads throughout the area. 15 participants received training provided by Tjalle Boorsma withAsociacion Armonia, and Joaquin Aldabe and Arne Lesterhuis with WHSRN Executive Office. The training included theoretical presentations and practical training in the field.
Field training by Joaquín Aldabe. Photo: Arne Lesterhuis.
Between September 3and September 12, 2021 a total of 948 km of survey transects were covered by the six field teams and a total of 673 Buff-breasted Sandpipers, representing over 1% of the global population, were counted. In addition, during the same period 1,083 individuals were counted during surveys at Barba Azul, so a minimum of 3% of the global population of the species were present in the Llanos de Moxos during the study periodof virtually all Buff-breasted Sandpipers were found in areas called “Bajios”, which is river-edge short grass. This is also the habitat where at Barba Azul the species is found and appears to be the key habitat for the species in the Llanos de Moxos.
Apart from the Buff-breasted Sandpiper, 11 other migratory shorebird species were observed of which the most common were the Pectoral Sandpiper (452 individuals), Upland Sandpiper (210 individuals), and Solitary Sandpiper Tringa solitaria (153 individuals).
Left: Bajio, Buff-breasted Sandpiper habitat at Llanos de Moxos, Bolivia. Right: Tjalle Boorsma counting Buff-breasted Sandpipers. Photos: Arne Lesterhuis
After the surveys, Joaquín Aldabe, WHSRN’s Ranching and Shorebirds Conservation Specialist visited Barba Azul to provide technical support and learn about their grassland management program that includes ranching. In this reserve, livestock grazing is being used as a conservation tool to provide adequate habitat for grassland shorebirds and other grassland bird specialists. Together with the person in charge of the management of the livestock, Joaquín and Tjalle fully revised the management system and exchanged experiences. As a result, several measurements for several indicators were added to the management protocol, which will improve decision making To support these new indicators, a workshop was conducted on taking abundance estimates using Distance Sampling, along with techniques for data collection and interpretation.
Joaquín Aldabe, Ranching and Shorebird Conservation Specialist from WHSRN Executive Office at the Llanos de Moxos . Photo: Tjalle Boorsma.
Understanding how the Buff-breasted Sandpiper use the Llanos de Moxos and how to manage the grasslands in a way that both the species and the landowners profit is of critical importance. A major threat to area is new land use laws that were approved in 2019. This along with an agricultural development plan for Bolivia’s Beni Department, are rapidly driving the conversion of natural grasslands and wetlands to soy and rice fields, threatening critical habitat for the Buff-breasted Sandpiper and other shorebirds.
The surveys carried out in September 2021 help to better understand habitat use and selection by the Buff-breasted Sandpiper in this natural grassland system, showing a preference for the short grass “bajios”. Future efforts should focus specifically on identifying and mapping all these bajios in the Llanos de Moxos and then studying the fidelity and turnover at these sites to understand the importance of these areas and ensure the protection and management of this critical habitat.
Cover Photo: Buff-breasted Sandpipers at Llanos de Moxos, Bolivia. Photo: Ruben Layme.
