Comparison of demographic parameters in Pacific and Atlantic colonies of Black-legged Kittiwakes (mean + SE).
- (a) Data from 1988–91 (Hatch et al. 1993a).
- (b) Average survival from 1955–98 (estimated from Coulson and Strowger 1999).
- (c) Based on the formula (2-m)/2m where m is annual mortality (Lack 1954).
- (d) Data from 1960–89 (Hatch et al. 1993b).
- (e) Data from 1954–82 (estimated from Coulson and Thomas 1985a).
| Parameter | Alaska | England |
| Adult survival (% per year) | 92.6 ± 0.01a | 81.0 ± 1.5b |
| Adult life expectancy (years) | 13.0c | 4.8c |
| Productivity (chicks/pair/year) | 0.3 ± 0.03d | 1.2 ± 0.03e |