Birds of a feather flock together? Winter dispersion of Southern Rockhopper and Magellanic penguins.

BARRIONUEVO, MELINA; MORGENTHALER, ANNICK; LOVOSKI, SIMEON; MARCHISIO, NAHUEL; MILLONES, ANA; FRERE, ESTEBAN

Conferencia; 11th International Penguin Conference; 2023

We studied the non-breeding dispersion of Magellanic(Spheniscus magellanicus, MP) and Southern Rockhopper (Eudyptes chrysocomechrysocome, SRP) penguins with geolocators. We analyzed spatial movementcharacteristics, and phenology and studied spatial- , environmental- andtrophic (via stable isotopes in blood)- niche overlap among : a) three MP’colonies located along the Argentinean coast (n=1 year & 31 penguins), andb) between MP and SRP breeding in close proximity (25km apart, n=3 years &31 penguins). We found similar trip lengths and dispersal distances among MPcolonies. They all headed northwards, which resulted in the northern and thecentral colonies facing similar oceanographic features and exploitingcomparable trophic niches (anchovy domain) in contrast to individuals breedingfurther south that remained in the sprat domain. In fact, central colonyspatial overlap was 44% and 38% with northern and southern colonies, whilenorthern and southern overlap a 19%. Between SRP and MP, there were no differences in the maximum distancereached but in total distances travelled (x̄SRP=1220±36.2km, x̄MP=1135±66.9km) and both headed northwards too.Also, MP departed 12 days earlier than SRP and returned 21 days before,dispersing 9 days less than SRP . The overall interspecific spatial overlap was42.94 % (but in 2021 SRP performed a strange migration which leads to28.51%).   Isotopic niches, at arrival,of SRP and MP did not overlap; SRP was situated on lower trophic levels andexpressed a more pelagic diet/habitat. Our results indicated spatial andtrophic niche segregation among MP`s colonies and between the two speciesbreeding in proximity during post breeding period. ver  libro de resúmenes adjunto. p. 61