An investigation on the relationship between the number of Barn Swallow (Hirundo rustica) and environmental parameters in Jelebu, Peninsular Malaysia

Swallows (Hirundo spp.) inhabit a variety of habitats in both tropical and temperate zones. Barn Swallows (Hirundo rustica), in particular, frequently roost in large numbers and construct mud nests on buildings, causing nuisance to humans. At the Glami Lemi Biotechnology Research Centre (GLBRC), which is located in Peninsular Malaysia, there are certain structures that are frequently utilised by a large number of swallows for perching and resting. This results in the defacement of the exterior walls caused by their droppings. Hence, the analysis presented in this paper delves into the factors influencing their presence and numbers. The objective of this study was to examine the fluctuations in the number of perched Barn Swallows and their relationship with three environmental parameters: temperature, relative humidity, and light intensity. Three hours of observation were conducted in two different sessions (i.e., morning and afternoon) three times per week for one year. The results showed that the number of Barn Swallows perched appeared to be stable throughout the year, except for November and December, when it increased tremendously and reached its peak. A Spearman rank analysis was conducted to investigate the correlation between the number of swallows perched and the environmental parameters. The analysis was restricted to only periods when the birds were present. A significant effect of relative humidity and temperature was observed for the morning session, promoting the relationship between the environmental parameters and the perching/resting behaviour of this species. This situation is parallel with the afternoon session, where all three environmental parameters showed a significant effect on swallows' numbers. This study not only provides valuable information to the GLBRC's management to effectively anticipate appropriate steps to mitigate the influx of Barn Swallows but also enhances our knowledge of the perching/resting behaviour of this species.