Adult Migrations and Habitat Use
229
Solitary nesting also occurs at Rancho Nuevo (Rostal et al., 1997) and other
beaches. A small number of females regularly nest on the Texas coast (Shaver,
1998), and very rarely on western Atlantic beaches such as Florida (Fletemeyer,
1990; Meylan et al., 1990a; Libert, 1998; Johnson et al., 2000), North Carolina
(T. Conant, unpublished data cited in Bowen et al., 1994), and South Carolina.
Nesting has been documented as far south as Colombia (Chavez and Kaufmann,
1974); however, Kemp’s ridleys rarely nest south of the tip of the Yucatan Peninsula
(Marquez, 1994).
After the last clutch is oviposited, females begin postnesting migrations away from
their nesting beach, traveling north or south along the coast (Mysing and Vanselous,
1989; Byles, 1989; Shaver, 1999; 2001). Postnesting migrations have been recorded
as far south as Colombia (Marquez, 1994) and as far north as Virginia; however, most
Kemp’s ridleys migrate to areas concentrated between north Texas coastal waters and
Campeche, Mexico (Chavez, 1969; Pritchard and Marquez, 1973; Byles, 1989; Shaver,
1999; 2001). These long-distance migrations encompass hundreds of kilometers
(Byles, 1989) and occur primarily in shallow waters less than 50 m deep (Byles, 1989;
Renaud, 1995; Renaud et al., 1996; Shaver, 1999; 2001). Females may establish
relatively circumscribed ranges in coastal waters for several months (Byles, 1989;
Byles and Plotkin, 1994), suggesting that resident feeding areas exist.
In contrast to the females, adult males appear to be nonmigratory. Shaver et al.
(in press) tracked 11 adult male Kemp’s ridleys, and most of them remained resident
in coastal waters near Rancho Nuevo for several months after the nesting season.
Only one male migrated away from the breeding grounds; he migrated to the north
Texas coast near Galveston. This is quite different from the generalized pattern that
has been described for male sea turtles (Rostal, 1991). Most males depart the
breeding grounds by the time the greatest number of females emerge to lay eggs
(i.e., when most females have already copulated) (Hendrickson, 1958; Booth and
Peters, 1972; Ehrhart, 1982; Frazier, 1985) and migrate to distant feeding grounds
(Plotkin et al., 1995; 1997; Hays et al., 2001b).
8.5 HAWKSBILL, ERETMOCHELYS IMBRICATA
Hawksbills are distributed in tropical waters throughout much of the Atlantic, Pacific,
and Indian Oceans (Witzell, 1983). Hawksbills live in close association with hardsubstrate communities such as coral reefs, where they forage primarily on sponges
(Meylan, 1988), and may also occur in coastal lagoons and bays. Hawksbills were
once believed to be nonmigratory residents of reefs adjacent to their respective
nesting beaches (Hendrickson, 1980; Witzell, 1983; Frazier, 1985), but postreproductive tagging, telemetry, and genetic studies have revealed that hawksbills do
indeed migrate and that many are highly migratory, traveling hundreds to thousands
of kilometers between nesting beaches and foraging areas (Meylan, 1982; Parmenter,
1983; Broderick et al., 1994; Byles and Swimmer, 1994; Groshens and Vaughan,
1994; Miller et al., 1998; Meylan, 1999; Prieto et al., 2001). Data from one adult
male hawksbill marked and later recaptured indicate that males are also highly
migratory (Nietschmann, 1981).
1123 book.book Page 229 Monday, November 11, 2002 11:11 AM
229
Solitary nesting also occurs at Rancho Nuevo (Rostal et al., 1997) and other
beaches. A small number of females regularly nest on the Texas coast (Shaver,
1998), and very rarely on western Atlantic beaches such as Florida (Fletemeyer,
1990; Meylan et al., 1990a; Libert, 1998; Johnson et al., 2000), North Carolina
(T. Conant, unpublished data cited in Bowen et al., 1994), and South Carolina.
Nesting has been documented as far south as Colombia (Chavez and Kaufmann,
1974); however, Kemp’s ridleys rarely nest south of the tip of the Yucatan Peninsula
(Marquez, 1994).
After the last clutch is oviposited, females begin postnesting migrations away from
their nesting beach, traveling north or south along the coast (Mysing and Vanselous,
1989; Byles, 1989; Shaver, 1999; 2001). Postnesting migrations have been recorded
as far south as Colombia (Marquez, 1994) and as far north as Virginia; however, most
Kemp’s ridleys migrate to areas concentrated between north Texas coastal waters and
Campeche, Mexico (Chavez, 1969; Pritchard and Marquez, 1973; Byles, 1989; Shaver,
1999; 2001). These long-distance migrations encompass hundreds of kilometers
(Byles, 1989) and occur primarily in shallow waters less than 50 m deep (Byles, 1989;
Renaud, 1995; Renaud et al., 1996; Shaver, 1999; 2001). Females may establish
relatively circumscribed ranges in coastal waters for several months (Byles, 1989;
Byles and Plotkin, 1994), suggesting that resident feeding areas exist.
In contrast to the females, adult males appear to be nonmigratory. Shaver et al.
(in press) tracked 11 adult male Kemp’s ridleys, and most of them remained resident
in coastal waters near Rancho Nuevo for several months after the nesting season.
Only one male migrated away from the breeding grounds; he migrated to the north
Texas coast near Galveston. This is quite different from the generalized pattern that
has been described for male sea turtles (Rostal, 1991). Most males depart the
breeding grounds by the time the greatest number of females emerge to lay eggs
(i.e., when most females have already copulated) (Hendrickson, 1958; Booth and
Peters, 1972; Ehrhart, 1982; Frazier, 1985) and migrate to distant feeding grounds
(Plotkin et al., 1995; 1997; Hays et al., 2001b).
8.5 HAWKSBILL, ERETMOCHELYS IMBRICATA
Hawksbills are distributed in tropical waters throughout much of the Atlantic, Pacific,
and Indian Oceans (Witzell, 1983). Hawksbills live in close association with hardsubstrate communities such as coral reefs, where they forage primarily on sponges
(Meylan, 1988), and may also occur in coastal lagoons and bays. Hawksbills were
once believed to be nonmigratory residents of reefs adjacent to their respective
nesting beaches (Hendrickson, 1980; Witzell, 1983; Frazier, 1985), but postreproductive tagging, telemetry, and genetic studies have revealed that hawksbills do
indeed migrate and that many are highly migratory, traveling hundreds to thousands
of kilometers between nesting beaches and foraging areas (Meylan, 1982; Parmenter,
1983; Broderick et al., 1994; Byles and Swimmer, 1994; Groshens and Vaughan,
1994; Miller et al., 1998; Meylan, 1999; Prieto et al., 2001). Data from one adult
male hawksbill marked and later recaptured indicate that males are also highly
migratory (Nietschmann, 1981).
1123 book.book Page 229 Monday, November 11, 2002 11:11 AM