Researcher: Pete Hancock
Region: Botswana
Background
The Bateleur (Terathopius excaudatus) is currently regarded as a globally threatened species in Botswana and listed as a “Bird of Conservation Concern”. While Bateleur populations are stable in large national parks and protected areas, outside these areas their population has suffered an 80% decline. The decrease outside protected areas is attributed to habitat loss, secondary effects of poisoning on farms, and a lack of carrion, the Bateleur’s principal food resource. The current population size and recent trends of this species in Botswana are unknown.
This preliminary project will contribute data on the factors influencing the spatial and temporal distribution of Bateleurs, where conservation awareness may be required, and it will contribute to the conservation status of the wildlife management areas (WMA) in Botswana.
Once a species has been identified as requiring conservation concern, BirdLife Botswana formulates a ‘Species Action Plan’ based on the bird’s status, biology and stakeholder participation. The plan involves coordinating habitat research, conservation and education programmes. BirdLife Botswana will thus be able to assess the data collected in this project and update the status of the Bateleur.
Objectives
The principal objective of this study is to assess the spatial and temporal distribution of Bateleur Eagles and determine if there are any negative anthropogenic and natural factors impacting on populations inside and outside conservation areas in Botswana.
Methodology
1) To determine the spatial and temporal distribution of adult and juvenile Bateleurs in Botswana.
- Establish the sex (male and female show sexual dichromatism and are therefore easy to identify in the air) and the age class of every Bateleur seen during the survey. This data may reveal the ratio of adults to juveniles.
- Map the distribution of Bateleurs and display the data geographically with the use of GIS. The distribution maps may indicate productive breeding sites, important habitat requirements as well as any seasonal and local movements for this species in Botswana.
2) To identify Bateleur nesting sites in the Okavango sand tongue regions and Linyanti Concession.
- The observers will survey the woodland tree canopy and record the presence of nests; identify all raptor species, nest contents, nest-tree species; approximate height above ground and above or below tree canopy and the GPS coordinates.
- Map the Bateleur nesting sites for annual monitoring purposes. To date only two Bateleur nesting sites have been identified in Botswana.
3) To determine a population estimate of adults in Botswana.
- Count the number of observed adult and juvenile Bateleurs to establish the key areas of high density and average population density; this may be extrapolated to determine the breeding population status of adults in the concession areas. With the use of this data, any decrease or increase in the Bateleur populations may be monitored on an annual basis.
Aerial Survey
Two gyrocopters will be used to conduct an aerial survey and locate and monitor the Bateleurs and other raptors that are observed. Both aircraft will be flown simultaneously for two hours in the morning and the afternoon during the aerial surveys.Ground Survey
A ground survey of the sand tongue regions of the Delta will be conducted in NG 31 to locate Bateleur nesting sites in January and February 2010. The fieldwork will entail a ground survey on foot in mature woodland. The observer will collect the following data variables: nest site locality (GPS position), presence and number of adult and/or juveniles in the vicinity of the site; age; sex; cream/normal; habitat; species of tree nest site located within; approximate height above ground and above or below tree canopy; bird activity (bird perched on the nest, hunting/scavenging etc); presence of prey/scavenged items; associated bird species; as well as any other incidental data that may be useful to the study. Photographs where possible are to be taken to accompany the data.Updates
Annual Report 2011
The Bateleur (Terathopius excaudatus) is currently regarded as a globally threatened species in Botswana and listed as a “Bird of Conservation Concern.” While Bateleur populations are stable in large national parks and protected areas, outside these areas their population has suffered an 80% decline. The decrease outside protected areas is attributed to habitat loss, secondary effects of poisoning on farms, and a lack of carrion, the Bateleur’s main food source.The principal objective of this study is to assess the spatial and temporal distribution of Bateleur Eagles and determine if there are any negative anthropogenic and natural factors impacting on populations inside and outside conservation areas in Botswana. Certain parts of the Okavango Delta show some of the highest densities of Bateleurs especially in the juvenile and sub-adult age classes – this study aims to gain some insight into why this is the case.
Aerial and ground surveys are taking place within the study area and are looking at spatial and temporal distribution of adult and juvenile birds, as well as their sex and age ratios. Bateleur distribution will be mapped with the use of GIS and nesting sites in the Okavango sand tongue regions and Linyanti Concession identified and plotted for annual monitoring purposes. To date only two Bateleur nesting sites have been identified in Botswana. Overall population density will be determined, to establish key areas of high and average density; this may be extrapolated to determine the breeding population status of adults in the concession areas. With the use of this data, any decrease or increase in the Bateleur populations may be monitored on an annual basis.
Initial ground surveys consisting of road counts have been carried out in Chitabe, Santawane and Moremi Game Reserve during the rainy season.
Once a species has been identified as requiring conservation concern, BirdLife Botswana formulates a ‘Species Action Plan’ based on the bird’s status, biology and stakeholder participation. The plan involves coordinating habitat research, conservation and education programmes. BirdLife Botswana will thus be able to assess the data collected in this project and update the status of the Bateleur Eagle.
March 2010
Information being collected includes sex and age class structure as well as mapping of the distribution of the species, which may indicate important breeding sites, habitat requirements and any seasonal or local movements. Another important aspect of the project is to locate Bateleur nesting sites, of which there are very few known locations in Botswana. Due to the large study area of the Okavango Delta and northern Botswana, data collection is being conducted via aerial surveys from two gyrocopters flying at 70km/h at an average height of 25m above the tree canopy in the morning and the afternoon.This information will be used to inform the Ministry of Environment, Wildlife and Tourism, Botswana’s Department of Wildlife and National Parks and BirdLife Botswana of Bateleur numbers as well as update their status and the trends of adults and juveniles in Botswana
