Abstract:
Aspects of the breeding biology of two Lake Erie
Herri ng Gull colonies were studied in 1975 and 1976. In 1976 the
incubation attention given 2-egg and 3-egg clutches initiated early
and late in the season was measured. Brood size at one colony was
artificially increased or decreased by addition of chicks shortly
after hatching.
Hatching success was not consistently re~ated to clutch
size but early nesters were more successful than late nes'ters. Differences
in hatching success between 2-egg and 3-egg clutches were a function
of the time of clutch initiation with the clutch size having the
greater proportion of its nests initiated early in the season being
more successful.
The incubation attentiveness of parents of 2-egg and
3-ev,g , and early and late clutches was similar. Most nests were
incubated greater than 95% of the time although t heir hatching
success was similar ' to those incubated less than 75% of the time.
Fledging success, chick growth and weight at fledging
were similar among broods of one, two and three chicks and artificially
increased broods of four and five chicks. Fledging success was
highest for o.e chick broods reduced from two and three chick
broods.
