Unchanging diet in a stable colony: contemporary and past diet composition of black-legged kittiwakes Rissa tridactyla at Helgoland, south-eastern North Sea

Table 3 Occurrence, length (cm) and biomass (g) of fish prey found in stomachs of kittiwake nestlings and adults at Helgoland in 2001, 2002, 2004 and 2006

	Median no.	Max no.	N	N _o	Median fish length		Range fish length		Median biomass		Range biomass
	Median no.	Max no.	N	N _o	Chicks	Adults	Chicks	Adults	Chicks	Adults	Chicks	Adults
Whiting Merlangius merlangus	2	17	113	86	8	10	6–21	5–21	4	6	1–70	1–68
Poor cod Trisopterus minutus	1	1	2	2	14	–	13–15	–	31	–	25–38	–
Gadoid indet.	1	4	21	3	12	–	9–15	–	12	–	5–25	–
Lesser sandeel Ammodytes marinus	1	2	7	7	15	15	13–20	15–16	9	11	7–23	9–12
Great sandeel Hyperoplus sp.	2	2	2	2	22	–	21–23	–	27	–	23–30	–
Sandeel indet.	1	4	19	7	14	21	13–17	21–21	9	30	6–13	30–31
Herring Clupea harengus	1	3	9	6	9	11	9–10	9–14	5	11	4–6	4–17
Sprat Sprattus sprattus	2.5	3	13	12	10	11	6–13	11–12	8	11	7–18	9–13
Clupeid indet.	1	2	12	5	9	–	6–9	–	4	–	1–5	–
Scaldfish Arnoglossus laterna	4	4	4	4	–	9	–	7–11	–	8	–	3–13
Anchovy Engraulis encrasicolus	1	1	2	1	–	15	–	–	–	18	–	–
Goby Pomatoschistus sp.	1	1	1	1	–	6	–	–	–	2	–	–

Fish length and biomass were calculated based on otoliths and thus could not be derived for individuals, e.g. one Dab and one wrasse, identified according to objects other than otoliths
Median no. minimum number of individual fish per stomach containing remains of the respective prey species; Max no. Maximum number of individuals per stomach; N Total number of individuals recovered according to otoliths and other prey remains; N _o Total number of individual fish used for calculations of fish length and biomass

ISSN: 1438-3888