Natal homing in juvenile loggerhead turtles (Caretta caretta).
Juvenile loggerhead turtles (Caretta caretta) from West Atlantic nesting beaches occupy oceanic (pelagic) habitats in the eastern Atlantic and Mediterranean, whereas larger juvenile turtles occupy shallow (neritic) habitats along the continental coastline of North America. Hence the switch from oceanic to neritic stage can involve a trans-oceanic migration. Several researchers have suggested that at the end of the oceanic phase, juveniles are homing to feeding habitats in the vicinity of their natal rookery. To test the hypothesis of juvenile homing behaviour, we surveyed 10 juvenile feeding zones across the eastern USA with mitochondrial DNA control region sequences (N = 1437) and compared these samples to potential source (nesting) populations in the Atlantic Ocean and Mediterranean Sea (N = 465). The results indicated a shallow, but significant, population structure of neritic juveniles (PhiST = 0.0088, P = 0.016), and haplotype frequency differences were significantly correlated between coastal feeding populations and adjacent nesting populations (Mantel test R2 = 0.52, P = 0.001). Mixed stock analyses (using a Bayesian algorithm) indicated that juveniles occurred at elevated frequency in the vicinity of their natal rookery. Hence, all lines of evidence supported the hypothesis of juvenile homing in loggerhead turtles. While not as precise as the homing of breeding adults, this behaviour nonetheless places juvenile turtles in the vicinity of their natal nesting colonies. Some of the coastal hazards that affect declining nesting populations may also affect the next generation of turtles feeding in nearby habitats.
Bowen
Brian W
BW
Hawaii Institute of Marine Biology, University of Hawaii, PO Box 1346, Kaneohe, HI 96744, USA. bbowen@hawaii.edu
Bass
Anna L
AL
Chow
Shaio-Mei
SM
Bostrom
Meredith
M
Bjorndal
Karen A
KA
Bolten
Alan B
AB
Okuyama
Toshinori
T
Bolker
Benjamin M
BM
Epperly
Sheryan
S
Lacasella
Erin
E
Shaver
Donna
D
Dodd
Mark
M
Hopkins-Murphy
Sally R
SR
Musick
John A
JA
Swingle
Mark
M
Rankin-Baransky
Karen
K
Teas
Wendy
W
Witzell
Wayne N
WN
Dutton
Peter H
PH
D000704:Analysis of Variance; D000818:Animals; D001267:Atlantic Ocean; D001499:Bayes Theorem; D017931:DNA Primers; D004272:DNA, Mitochondrial / Q000235:genetics; D003710:Demography; D005247:Feeding Behavior / Q000502:physiology; D014644:Genetic Variation; D006239:Haplotypes / Q000235:genetics; D006702:Homing Behavior / Q000502:physiology*; D009656:North America; D012098:Reproduction / Q000502:physiology*; D017422:Sequence Analysis, DNA; D012726:Sexual Behavior, Animal / Q000502:physiology*; D014426:Turtles / Q000235:genetics / Q000502:physiology*
D017931:DNA Primers; D004272:DNA, Mitochondrial