THE EFFICIENCY OF DETECTING COLOR-BANDED HERRING-GULLS (LARUS-ARGENTATUS) AND LESSER BLACK-BACKED GULLS (LARUS-FUSCUS) AT THE BREEDING COLONY - PRACTICAL IMPLICATIONS FOR THE DETERMINATION OF ADULT SURVIVAL RATES
J. Calladine, THE EFFICIENCY OF DETECTING COLOR-BANDED HERRING-GULLS (LARUS-ARGENTATUS) AND LESSER BLACK-BACKED GULLS (LARUS-FUSCUS) AT THE BREEDING COLONY - PRACTICAL IMPLICATIONS FOR THE DETERMINATION OF ADULT SURVIVAL RATES, Colonial waterbirds, 20(1), 1997, pp. 41-46
The efficiency of finding color-banded Herring Gulls (Larus argentatus
) and Lesser Black-backed Gulls (L. fuscus) during repeated visits to
a mixed species breeding colony on the Isle of May was investigated. T
he most efficient period for finding Herring and Lesser Black-backed G
ulls was May and June, coincident with the main incubation and early c
hick-rearing periods. Ten ''searches'' during that period found 85%-90
% of surviving individuals, while 4 searches found >70%. Additional se
arches produced very few extra birds. When assessing annual survival r
ates from resightings of color-banded individuals, marking a relativel
y large study population is a more efficient method of increasing the
precision of survival estimates than additional effort searching for r
emaining, unseen birds.