Behaviour of leatherback sea turtles,Dermochelys coriacea, during the migratory cycle

Abstract

Leatherback sea turtles, Dermochelys coriacea, undertake broad oceanic movements. While satellite telemetry has been used to investigate the post-nesting behaviour of female turtles tagged on tropical nesting beaches, long-term behavioural patterns of turtles of different sexes and sizes have not been described. Here we investigate behaviour for 25 subadult and adult male and female turtles satellite-tagged in temperate waters off Nova Scotia, Canada. Although sex and reproductive condition contributed to variation in migratory patterns, the migratory cycle of all turtles included movement between temperate and tropical waters. Marked changes in rates of travel, and diving and surfacing behaviour, accompanied southward movement away from northern foraging areas. As turtles approached higher latitudes the following spring and summer, they assumed behaviours consistent with regular foraging activity and eventually settled in coastal areas off Canada and the northeastern USA. Behavioural patterns corresponding to various phases of the migratory cycle were consistent across multiple animals and were repeated within individuals that completed return movements to northern waters. We consider the potential biological significance of these patterns, including how turtle behaviour relates to predator avoidance, thermoregulation and prey distribution.

Prey landscapes help identify potential foraging habitats for leatherback turtles in the NE Atlantic

“…The seasonal presence of leatherback turtles in midlatitude North Atlantic habitats has been previously recorded (Bleakney 1965, Brongersma 1972, Godley et al 1998). More recently migratory movements into mid-latitude habitats have been demonstrated with satellite tracking (Ferraroli et al 2004, Hays et al 2004, James et al 2005a, Eckert 2006. The occurrence of leatherback turtles in habitats with sea temperatures that induce lethargy in hard-shelled species (Davenport 1997) supports the premise that leatherbacks have an endothermic capacity, thus remaining active in cool prey-rich waters (Davenport 1998, McMahon & Hays in press).…”

“…Surface currents can aggregate forage along coastal margins (Graham et al 2001) and within embayments (Houghton et al in press). The recorded behaviour of leatherback turtles in neritic (Eckert et al 1989) and pelagic habitats (Hays et al 2004, James et al 2005a suggest diving plays an important function in enhancing prey capture especially when epipelagic availability of gelatinous forage is poor (Davenport 1988). Leatherbacks exhibit a diel periodicity in diving behaviour, inhabiting shallower habitats by night and deeper habitats by day, presumably in response to vertical tracking of their diel migrating prey (Eckert et al 1989).…”

“…Movement studies using electronic tagging have offered significant insights into the selected habitats of fish (Sims et al 2003, Block et al 2005, reptiles (James et al 2005a, Eckert 2006 and birds (Croxall et al 2005). Assessing predator distribution with respect to the attributes of the environment encountered (e.g.…”

Evidence of migratory movements of olive ridley turtles (Lepidochelys olivacea) along the Brazilian coast

“…These facts, together with the present report, have lead us to believe that L. olivacea could be regularly migrating to the northeastern coast of Rio de Janeiro state, probably using this area as a feeding ground since the northeasterly winds prevailing during the spring-summer generate coastal upwelling (COSTA;FERNANDES, 1993;VALENTIN, 2001). Upwelling areas are often important as sea turtle feeding grounds (POLOVINA et al, 2004;JAMES et al, 2005;AMOROCHO;REINA, 2007). Also, the input of organic matter from the Paraíba do Sul River (21 o 36'57''S -41 o 00'50''W) could contribute to make the north-eastern coast of Rio de Janeiro state an important foraging ground for sea turtles.…”

Pre-nesting Movements of Leatherback Sea Turtles, Dermochelys coriacea, in the Western Atlantic

“…The foraging grounds of Atlantic Canada have been identified as critical habitat for mature leatherbacks (James et al, 2006), and both morphometric and physiological indicators have been used to determine that leatherbacks are capital breeders (James et al, 2005b;Davenport et al, 2011;Plot et al, 2013). Throughout the nesting season, leatherbacks rely on energy stores and become anorexic (Plot et al, 2013).…”