Meeting Abstract
The “rate of living” theory suggests a tradeoff between metabolism and survival and is supported by inverse correlations between metabolic rate and survival rates. Charadriiform seabirds are exceptions to this pattern because they live exceptionally long despite having sustained high metabolic rates. We investigate the tradeoff between metabolic rate and survival in Thick-billed Murres (Uria lomvia). Reproductive success increased with age between 7-11 years of age, before leveling off, with experience being a better predictor for reproductive success than age during the first 12 years of life. Reproductive success was lower during the final year of life compared to previous years and baseline cort higher, suggesting that death may be related to health effects evident in the last year of life. Hematocrit and metabolic rate appeared to decrease linearly with age, perhaps as a strategic adjustment to reduce the effect of heart disease in old age. Foraging ability appeared to be independent of age. When foraging conditions were experimentally worsened, time spent at the colony increased with age, with 33% of the youngest birds abandoning altogether. Furthermore, cort response levels to handling were higher in younger birds. We concluded that young birds were “prudent parents”, and willing to sacrifice future reproductive success for current offspring leading to an increase in reproductive success with age, while old murres showed signs of deteriorating health when 20-25 years.
