Temporal Patterns of Cooing Activity of the European Turtle-Dove Streptopelia turtur: Optimising Monitoring Schemes Based on Abundance Indices

Abstract

SummarySurveys based on abundance indices may still be the most cost-efficient method for monitoring programmes that aim to be extensive in time or space, but it is important to take into account differences in activity patterns when combining data collected at different times or from different areas. The European Turtle-dove Streptopelia turtur is a migratory game species that has declined in recent decades and for which identifying efficient and easy-to-apply monitoring schemes to assess changes in abundance is critical for adaptive management. We describe variation in cooing activity to help optimising Turtle Dove abundance monitoring schemes based on point-counts of cooing males. Cooing activity (number of minutes during a ten-minute sampling period when each Turtle Dove was cooing) declined markedly and linearly throughout the morning; in addition, it increased slightly from May to late June, and declined abruptly in the second half of July. The number of different turtle doves detected per ten-minute period significantly declined with time since dawn and was markedly lower after mid-July. Predicted abundance per observation point at dawn on 25 June (from a GLM per region including time and a quadratic relationship with date), correlated tightly (r = 0.95) with the average number of turtle doves detected at each point over multiple visits during the breeding season. Correlation of the latter with the number of birds observed in a single visit during the breeding period was weaker (0.68 ± 0.02). Estimated abundance per point was higher the longer the monitoring bout duration, but five-minute periods allowed detecting c. 80% of birds detected during ten-minute periods. To optimize Turtle Dove abundance monitoring schemes based on abundance indices, we suggest implementing five-minute samplings from mid-May to mid-July during the first three hours after dawn, and transforming the observed values into predicted values considering the date and time at which surveys were made, to obtain comparable results across observation points and years.—Arroyo, B., Moreno-Zarate, L., Fernández-Tizón, M., Sardà-Palomera, F., Bota, G. & Mougeot, F. (2023). Temporal patterns of cooing activity of the European Turtle-dove Streptopelia turtur: optimising monitoring schemes based on abundance indices. Ardeola, 70: 151-168.