Breeding Biology of the Long-tailed Shrike (Lanius schach) and Its Response to Brood Parasitism by the Asian Koel (Eudynamys scolopaceus)

The Long-tailed Shrike (Lanius schach) serves as a key host for the brood parasitic Asian Koel (Eudynamys scolopaceus). This study aims to investigate the breeding success, nesting patterns, and response to brood parasitism. Surveys of Long-tailed Shrike nests were carried out from March to August 2024, covering the breeding season. We searched for nests or adult shrikes through both walking and bicycle surveys in regions that were dominated by shrike-preferred habitats. Breeding activity peaked in May (37.5%), while the lowest activity was recorded in March, June, and July (12.5%). No breeding activity was observed in August. A total of eight Long-tailed Shrike (LTS) nests were identified, of which six were active and contained at least one egg. In total, 50% of nests were parasitized, and 50% were unparasitized. Breeding success of the LTS in parasitized and unparasitized nests was recorded as 55.56% and 58.75%, respectively, in relation to hatchlings, and also 36.11% and 47.78%, respectively, in relation to fledglings. The highest percentage of nesting materials commonly used by LTS for nest construction was fine grass (34.37%), followed by plastic threads (9.75%), ropes (7.45%), twigs (10.91%), leaves (0.51%), polythene (1.28%), root fibers (3.01%), synthetic nets (1%), cotton (0.22%), plant bark (0.73%), fabrics (1.20%), plastic bags (7.56%), and unidentified material (22%). The majority of nests (75%) were located at the periphery, and a few nests were built in central positions (25%) of the trees. Most nests were found in Mahogany trees, and the LTS primarily used Banana leaves (63.01%) for nest construction, but also used Acacia, Rain tree, and Mahogony leaves. These outcomes help to determine how brood parasitism affects host reproductive success. This study also highlights the urgent need for management of plastic pollution to reduce its integration into bird nests and to protect avian health.