L
oggerhead Turtles enjoy a widespread distribu-
tion in tropical and subtropical regions, and are
commonly found in coastal habitats, where food is
more plentiful. They are primarily carnivorous, and
have a very varied diet consisting chiefly of bottom-
dwelling marine invertebrates such as crustaceans,
molluscs and urchins; this may be supplemented
with jellyfish, fish, plants and algae. The turtles will
forage during daylight hours, and although most
dives do not exceed 30 minutes, Loggerheads are
capable of staying submerged for several hours,
especially in colder waters. They sleep while resting
on the seabed.
Male Loggerhead Turtles spend their entire lives at
sea, while females emerge onto dry land only briefly
to lay their eggs. Sexual maturity is acquired
relatively late in life, and although some females
first reproduce at 17 years of age, others must wait
until they are at least 30. Receptive females may
attract males using pheromones. The successful
suitor will mount the female, but can expect the
unwanted attention of rivals, who will attempt to bite
him whilst he is in an amorous embrace and may
inflict nasty wounds. Loggerheads are promiscuous
and multiple paternity is common.
In what may represent one of the longest seasonal
migrations of any marine animal, female Logger-
heads are driven to return to the beach where they
were born in order to nest. Some years ago one
female was tracked from Mexico across the Pacific
to a nesting site in Japan – a distance of 14,500km.
In 2015, a female from Western Australia was
tracked for more than 2,000km. The turtles navigate
both by using visual cues and by sensing and inter-
preting the Earth’s magnetic field. This has recently
been proven by correlating subtle changes in the
magnetic field with small corresponding shifts in
turtle nesting sites.
Mature females reproduce only every second or
third year, laying 3-5 clutches of eggs at intervals of
roughly 2-3 weeks during spring and summer. Each
clutch comprises an average of over 100 eggs,
which are deposited in a chamber which the female
excavates with her hind limbs, and later conceals as
carefully as possible. The most important nesting
areas are in Florida and on Masirah Island in Oman.
Estimates vary considerably, and can become
outdated very quickly, but it is probably safe to say
that each of these two sites is home to at least
15,000 Loggerhead nests each year. Australia has
two nesting areas, one of which is centred on the
southern part of the Great Barrier Reef, in Queen-
sland, and the other which stretches along the
Ningaloo coast and includes adjacent islands in
Western Australia. The latter can host up to 2,000
nests during the breeding season, with nesting
activity usually peaking in December.
Loggerhead Turtles exhibit temperature-dependent
sex determination, with an incubation temperature
‘Male Loggerheads spend their entire lives at
sea, while females emerge onto dry land only
briefly to lay their eggs.’
All images courtesy of Karen Hattingh,
Gnaraloo Turtle Conservation Program.