Mating ecology of a lek-breeding antelope

From a Darwinian viewpoint, life is about surviving long enough to reproduce. Across the animal kingdom, many systems have evolved for males and females to find and attract suitable mates. Lekking—in which males gather in a single area to court visiting females—is a spectacular and rare example of such a mating system. With aerial videography, spatial modelling, and deep learning algorithms, we are conducting the first-ever study of a lek-breeding system that incorporates fine-scale social interactions of every individual on the lek. By doing so, we will unravel structural and social drivers of mate choice and mating success in this unique system.

Emergent properties of the lek

A lek is an aggregation of displaying males that are each seeking to attract mates. Females visit leks to avail the apparently low-cost opportunity of sampling mates. Although rare, lekking species are present in nearly all animal classes—from insects and reptiles to fish, amphibians, birds, and mammals.

On leks, only few males mate with almost all of the females, setting the stage for strong sexual selection. How do females choose their mates? And which males are preferred over others? Decades of sexual selection research on leks has uncovered factors—such as male-male competition and mate-choice copying in females—that are associated with mating success of certain males. Now, thanks to recently available technology, we can expand our view beyond mate pairs to encompass the entire lekking collective.

The aim of the project is to understand, in mechanistic detail, how the social interactions of all individuals in the lek drives patterns of mate choice and mating success. Our study system, the blackbuck (Antilope cervicapra), is one of <2% of mammal species to adopt lekking as a breeding system. Blackbucks are widely distributed throughout India, but lekking in the species is extremely rare, occurring in only two populations.

We study the only two populations of lekking blackbuck—located in the states of Rajasthan and Gujarat—using multiple, simultaneously-flying Unmanned Aerial Vehicles (i.e. drones) that record leks throughout the season (a few weeks in March). We have developed a pipeline to capture bird’s-eye-view video of the entire lek for long periods of time, and then to map the simultaneous movements of all individuals. This involves spatially capturing an area, temporally aligning the videos collected by multiple drones, and finally determining the trajectories of all individuals in global coordinates.

Mechanisms of mate-choice on leks

As a result, we can quantify the spatial and temporal dynamics of local interactions on the lek. This allows us to test various mechanisms contributing to emergent properties on the lek. For example, recent work has shown that incorporating the dynamic aspects of spatial decision-making—specifically accounting for time-varying geometry—offers crucial insights for comprehending the interplay between movement and choice in animals. By quantifying individual movement within the lek, we not only capture these time-varying geometries for all individuals but also map the social interactions in which they engage, such as intrasex competition among males and mate-choice copying in females. Through this approach, we can unravel the structural and social drivers of mate choice and mating success in this unique system.

Data from the lek

The project’s object detection algorithm shows males (green), females (lime) and animal shadows (yellow bounding boxes). The circular patches are territorial markings that males defend.

Connecting human and animal societies

Our project Mating Ecology of a Lek-breeding Antelope goes by the name ‘MELA, which is more than an abbreviation. In hindi, the word refers to a gathering of people at a fair or a public event organised to celebrate a special occasion. The local communities around Velavadar National Park (one of our two study sites) call the blackbuck lek a ‘mela,’ or a gathering of the antelopes.

Alongside the science, a central aim of the MELA project is to improve the practice of knowledge dissemination within the communities who live alongside the blackbucks. To that end, we have established collaborations with the art institution Akademie Schloss Solitude, as well as forest officials and local universities. Through these collaborations, we hope to build capacity in conservation, and engage the local communities with the scientific quest to understand the animals and their unique mating system.

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