Movement patterns and habitat preference of oilbirds (Steatornis caripensis) in the southern andes of Colombia

Abstract

Habitat use and movement patterns in animals are usually determined by the availability of food, morphological and physiological traits, social systems, and safe sites to complete vital cycles. The objective of this study was to estimate the home-range area, daily traveled distance, and patterns of space use by Oilbirds (Steatornis caripensis), and the factors that can affect them in Cueva de Los Guacharos National Park (Huila, Colombia). We attached GPS devices to five individuals and recovered information from three. Home ranges were estimated by minimum convex polygon (MCP), 95 and 50% kernel methods. Traveled distances were estimated as the sum of the linear distances between sampling points (every 30 min), and patterns of habitat use were evaluated through ecological-niche factor analysis (ENFA), including forest cover, altitude, and degree of fragmentation. Analysis of habitat preference was done using 25 vegetation plots established in frequently used areas and species richness, and the proportion of consumed plants was compared with other locations within their distribution range. Home-range area was estimated to be 4517 km2, possibly an underestimation due to reduced sample size. The average traveled distance per night was 55 km (range: 0-112 km). Analyses of habitat use showed a clear preference for areas with higher forest cover. Height above sea level was also largely associated with frequencies of habitat use, indicating a low use of areas above 3000 m, while the degree of fragmentation was not a strong predictor of habitat use. Finally, vegetation plots in frequently used areas showed a higher abundance of fruiting trees consumed by Oilbirds than control plots. Overall, Oilbirds have amazing movement capacity, being able to use distant landscape elements, and showing a clear preference for areas with forest cover, lower altitude, and areas with a high representation of the plant species they consume.