Glossy Ibis 



The glossy ibis is one of the earlier nesters anong the wading birds 

 (Fig. 38). More data are required for this species especially in the 

 mid-Atlantic region. 



White Ibis 



Only one pair nested in Virginia in 1977. 



SUMMARY 



The nesting chronology of seabirds and waders is quite variable through- 

 out the north Atlantic both geographically and from year to year. Latitudinal 

 differences are not large for most species. At a given colony, differences of 

 2 months in peak egg-laying between consecutive years are quite common in 

 gulls, terns, and herons. Even colonies which are located close together may 

 be quite different in chronology. The factors involved in the timing of 

 reproduction are unclear. For terns, food supply probably influences egg- 

 laying timing more than other environmental factors (I. Nisbet pers. comm.). 

 Food abundance may act as a cue in signalling the optimum time for onset of 

 egg production or it may be the nutritional bottleneck for egg formation in 

 females. For example, in some terns a scarce food supply may delay egg- 

 laying and clutches may be smaller. In addition to environmiental factors, 

 demographic aspects may also affect nesting chronology among colonies. In 

 large, traditional gull colonies, a large proportion of breeders will be 

 older, experienced birds; while at small, new colonies, young birds will 

 often predominate (Kadlec and Drury 1968a). Older birds generally arrive 

 and initiate egg-laying earlier than young birds (Coulson and White 1960). 



With son.e exceptions, wading birds arrive and begin nesting activity 

 somewhat earlier than seabirds, but the overlap is great. Most waterbird 

 nesting activity begins in early flay and concludes by mid to late July by 

 which time the majority of young have fledged. Renesting may occur after 

 initial nesting has failed so that for some species, young do not fledge 

 until August or September. The May to July period is the most important 

 period for nesting waterbirds and protection of nesting areas is most 

 valuable at this time. 



Ill 



