Figure 1.
Breeding intervals of the population of sooty terns on Ascension Island.
Breeding intervals plotted against date of first hatching of the sooty tern populations breeding at Mars Bay (open bars) and Waterside (grey bars) colonies on Ascension Island in the South Atlantic. Short-dashed line indicates a sub-annual breeding interval of 9.6 months while long-dashed line indicates one that is annual.
Table 1.
Summary of investment in, and outputs from, re-capturing adult sooty terns on Ascension Island ringed while incubating between 1996 and 2012 inclusive.
Figure 2.
Breeding intervals of individual sooty terns on Ascension Island.
The frequency distribution of breeding intervals (bar widths of 30 days) of individual sooty terns based upon their re-capture during incubation following their initial ringing (on day 0) as incubating adults on Ascension Island in the South Atlantic.
Figure 3.
Composition of breeding cycles of sooty terns breeding annually and sub-annually.
Relative lengths (in days) of stages (court. – courtship, inc. – incubation, chick – chick-rearing and migr. – migration) in the sub-annual and annual breeding cycles of sooty terns. Data are from this study for sub-annually breeding birds and from Schreiber et al. [32] (and references therein) for annually breeding populations.
Figure 4.
Breeding colonies and day length in sooty tern populations which breed annually and sub-annually.
Annual changes in day length during 2012 at colonies where sooty terns breed annually and at Ascension Island where they breed sub-annually.