Playback survey trial for the Little Owl Athene noctua in the UK

Figures & data

Table 1. Cumulative detection and response rates of Little Owls using nocturnal playback surveys across multiple visits (March to April 2015) to 12 2 × 2 km squares, each containing three broadcast locations (A, B and C) spaced 500 m apart along a linear transect. Detection rates are the proportion of survey squares with known breeding pairs (n = 8 squares) in which Little Owls were seen or heard. Response rates refer to the proportion of playback episodes in each location (n = 12 per visit) in which Little Owls responded vocally across all survey squares. The sample size for detection and response rates for the final visit was 32 and 48, respectively.

	Visits	Broadcast location
		A	B	C	Any
Detection rate	1	0.5	0.75	0.75	1.00
	2	0.88	1.00	0.88	1.00
	3	0.88	1.00	0.88	1.00
	4	0.88	1.00	0.88	1.00
Response rate	1	0.67	0.83	0.75	1.00
	2	0.75	0.83	0.79	1.00
	3	0.75	0.81	0.75	0.94
	4	0.69	0.75	0.75	0.92

Figure 1. The likelihood of detecting Little Owls through response to playback over increasing distance from a known breeding site (nest box). The solid line represents the predicted response from a binomial GLM bounded by the 95% confidence interval (dashed lines).

Figure 2. Mean number (±se) of Little Owl responses to playback calls from four visits (cumulatively) across multiple buffer sizes (m) around occupied nest boxes (n = 8).