Comparing call-playback to an observation-only method to survey Grey Partridge Perdix perdix on hill farms in northern England

Abstract

Capsule: Call-playback in spring can be a practical method to survey Grey Partridges Perdix perdix in rough grasslands with abundant cover. However, further research is required to investigate movements and other responses to call-playback.

Aims: To compare call-playback with an observation-only method to survey Grey Partridges in rough grasslands with abundant cover, and to undertake a pilot study to consider whether bird behaviour conforms to point distance sampling assumptions.

Methods: Grey Partridges were surveyed using two separate methods: call-playback and observation-only, at 10 equally spaced points along 14 independent 4 km routes at 3 study sites in northern England. Surveys were undertaken at dawn and dusk in spring (March and April) and again in summer (August and September).

Results: In spring, call-playback registered at dusk fourfold and at dawn almost twice as many Grey Partridge encounters as the observation-only method. Methods did not differ in summer. In spring, using call-playback registered three times more encounters in rough grasslands with tall, dense cover than the observation-only method. Methods did not differ in summer. Grey Partridge encounter density estimates did not differ significantly between methods or seasons.

Conclusion: Using call-playback in spring increased the numbers of Grey Partridge encounters and can be a practical survey method, but further research is required to compare results against known populations and to investigate movements and other responses to call-playback, which may violate distance sampling assumptions.