When celibacy matters: incorporating non-breeders improves demographic parameter estimates

Area of Science:

• Ecology
• Population Biology
• Conservation Biology

Background:

• In long-lived species, a significant portion of the adult population may not breed annually.
• Estimating demographic parameters solely from breeding individuals can be misleading.
• Observable non-breeders (ONB) are present but often overlooked in population studies.

Purpose of the Study:

• To demonstrate the importance of incorporating ONB into demographic models.
• To assess the impact of ONB on estimates of survival, return, breeding, hatching, and fledging probabilities.
• To investigate age-dependent effects on demographic estimates when ONB are considered.

Main Methods:

• Utilized multi-state capture-mark-recapture analyses on the wandering albatross (Diomedea exulans).
• Compared demographic estimates from models that included ONB versus those that ignored them.
• Evaluated bias, precision, and accuracy of parameter estimates.

Main Results:

• Ignoring ONB resulted in biased and less accurate estimates of breeding probability and survival.
• These biases were amplified in age-dependent analyses, particularly for older individuals.
• Overestimation of survival at old age and underestimation of reproductive senescence were observed when ONB were excluded.

Conclusions:

• Accounting for ONB is crucial for accurate demographic parameter estimation in long-lived species with partial breeding.
• Inclusion of ONB improves population dynamics models and evolutionary conclusions on senescence.
• This approach is vital for species where non-breeding is common, enhancing ecological and conservation insights.