Population trend of Adélie penguins breeding in Hope/Esperanza Bay, Antarctica

Abstract

Several studies reported decreases in populations of Adélie penguins in the north and west of the Antarctic Peninsula. Thus, from 1994 to 2019 we studied the population trend of Adélie penguins at Hope/Esperanza Bay. For such propose, following the CCAMLR-CEMP Methods_A.6-procedure_A-B, we estimated the numbers of breeding pairs, the clutch size, the hatching success, and the survival of chicks to crèche (breeding success). The survival of crèched chicks to adults, and adults? annual survival were obtained from the literature. We constructed a matrix population model to estimate the eigenvalues (λ) as a measure of grow rate of the population. The logarithm of λ1 (dominant eigenvalue) is equivalent to the per capita grow rate (r), so the population grows if λ1 is higher than one, remains stable if is one, and decrease if lower than one. Every two years, using a temporal series of six years, we estimated λ1 for each period; then we compute an average λ1. Survivorships were: eggs to hatching=0.77; guard chicks to fledged chicks=0.87; fledged chicks to two years age=0.26; adults per year=0.89. The estimated fecundity was 1.9 eggs/female, and due the ratio female/male reported is 1:1, the estimation of net reproductive rate (R0) was 0.95. The average value of λ1 was 1.07. Results suggest that during the study period, the colony remained stable. Given that populations are complex systems, to advance in the knowledge of the dynamic of this population it is important to identify which parameters have the higher sensitivity (stronger influence on λ1).