TY - JOUR
T1 - Differences in foraging location of Mexican and California elephant seals
T2 - Evidence from stable isotopes in pups
AU - Aurioles, David
AU - Koch, Paul L.
AU - Le Boeuf, Burney J.
PY - 2006/4
Y1 - 2006/4
N2 - Female northern elephant seals, Mirounga angustirostris, from Año Nuevo (AN) in central California feed offshore in mid-latitude waters (40°-55°N). Migratory patterns and foraging locations of seals from Mexico are unknown. Rookeries on San Benitos (SB) islands in Baja California Sur, Mexico, are ∼1,170 km south of AN. Although the colonies are similar in size, seals from SB begin breeding earlier and have an earlier breeding birthing peak than seals from AN. To determine if the foraging location of seals from Mexico was similar to that of seals from California, we measured δ13C and δ15N values in the hair of 48 suckling pups at SB and 37 from AN, assuming that their isotopic signatures reflected those of mothers' milk, their exclusive diet. The mean δ13C and δ15N values for SB pups (-16.1‰± 0.9‰ and 17.7‰± 0.9‰, respectively) were significantly higher than those for AN pups (-17.6‰± 0.4‰ and 15.6‰± 1.0‰, respectively). From data on environmental isotope gradients and known behavior of SB and AN populations, we hypothesize that the isotope differences are due to females in the SB colony foraging ∼8°south of seals from AN. This hypothesis can be tested by deployment of satellite tags on adult females from the SB colony.
AB - Female northern elephant seals, Mirounga angustirostris, from Año Nuevo (AN) in central California feed offshore in mid-latitude waters (40°-55°N). Migratory patterns and foraging locations of seals from Mexico are unknown. Rookeries on San Benitos (SB) islands in Baja California Sur, Mexico, are ∼1,170 km south of AN. Although the colonies are similar in size, seals from SB begin breeding earlier and have an earlier breeding birthing peak than seals from AN. To determine if the foraging location of seals from Mexico was similar to that of seals from California, we measured δ13C and δ15N values in the hair of 48 suckling pups at SB and 37 from AN, assuming that their isotopic signatures reflected those of mothers' milk, their exclusive diet. The mean δ13C and δ15N values for SB pups (-16.1‰± 0.9‰ and 17.7‰± 0.9‰, respectively) were significantly higher than those for AN pups (-17.6‰± 0.4‰ and 15.6‰± 1.0‰, respectively). From data on environmental isotope gradients and known behavior of SB and AN populations, we hypothesize that the isotope differences are due to females in the SB colony foraging ∼8°south of seals from AN. This hypothesis can be tested by deployment of satellite tags on adult females from the SB colony.
KW - Carbon
KW - Elephant seal
KW - Feeding areas
KW - Isotope
KW - Migration
KW - Mirounga angustirostris
KW - Nitrogen
UR - http://www.scopus.com/inward/record.url?scp=33645302407&partnerID=8YFLogxK
U2 - 10.1111/j.1748-7692.2006.00023.x
DO - 10.1111/j.1748-7692.2006.00023.x
M3 - Artículo
SN - 0824-0469
VL - 22
SP - 326
EP - 338
JO - Marine Mammal Science
JF - Marine Mammal Science
IS - 2
ER -