Diet of Black-legged Kittiwakes (Rissa tridactyla) feeding chicks at two Irish colonies highlights the importance of clupeids

Figures & data

Table 1. Frequency of occurrence of prey items in regurgitates of Kittiwakes during the early chick-rearing period at (a) Rathlin Island, Northern Ireland and (b) Lambay Island, Republic of Ireland in (i) 2009 and (ii) 2010. Sample sizes are given as numbers of birds (b) and numbers of regurgitates (N). Values are given in each column for numbers and percentages are given in parentheses. Data on reproductive success have been extracted from Chivers et al. (2012a).

				Frequency of occurrence (%)
				Clupeids		Sandeels		Gadoids
Colony	Year	(b)	(N)	b (%)	N (%)	b (%)	N(%)	b (%)	N (%)	Reproductive success (chicks fledged nest^−1)
(a) Rathlin	(i) 2009	20	21	20 (100.0)	21 (100.0)	2 (10.0)	2 (9.5)	0 (0.0)	0 (0.0)	1.11 ± 0.11 (N = 37)
	(ii) 2010	3	4	3 (100.0)	4 (100.0)	0 (0.0)	0 (0.0)	0 (0.0)	0 (0.0)	0.45 ± 0.08 (N = 38)
	Subtotal	23	25	23 (100.0)	25 (100.0)	2 (8.7)	2 (8.0)	0 (0.0)	0 (0.0)	0.78 ± 0.10 ( N = 75)
(b) Lambay	(i) 2009	8	8	8 (100.0)	8 (100.0)	1 (12.5)	1 (12.5)	3 (37.5)	3 (37.5)	1.62 ± 0.08 (N = 50)
	(ii) 2010	12	15	8 (66.7)	11 (73.3)	9 (75.0)	10 (67.7)	3 (25.0)	4 (26.7)	0.93 ± 0.05 (N = 390)
	Subtotal	20	23	16 (80.0)	19 (82.6)	10 (50.0)	11 (47.8)	6 (30.0)	7 (30.4)	1.28 ± 0.07 ( N = 440)
	Grand total	43	48	39 (90.7)	44 (91.7)	12 (27.9)	13 (27.1)	6 (14.0)	7 (14.6)	1.03 ± 0.08 ( N = 515)