Sea Turtle Recovery Action Plan for Barbados - WIDECAST

CEP Technical Report No. 12
39 nesting activities, indicating that residents were observing 14-43% (39/90 - 39/270) of the
actual nesting activity. Using public reports for each month, and adjusting each by a factor of
14-43%, the total number of nestings for each month was estimated and, from this, the total
number per year. The estimated number of hawksbill nests in 1987 ranged between 120-362.
Public involvement in monitoring has increased markedly since 1987, with residents reporting
71, 60, and 91 nests in 1989, 1990, and 1991, respectively. Close examination of the dates (eggs
laid fewer than 12 days apart are unlikely to have been laid by the same female) and locations of
these nests suggests that a minimum of 37 individuals nested in 1989, 25 in 1990, and 47 in
1991. Based on five nests per female (per breeding season), an estimated 120-230 nests may
have been made annually between 1989-1991; if so, the public reported roughly one-third of
them.
In addition to valuable monitoring efforts on the part of the general public, an intensive
survey was carried out on 1.5 km of the south coast during 1989-1991 (see also section 4.112).
The number of nests deposited on this beach per year was calculated based on daily early
morning beach censuses. This information was supplemented by reports from hotel nightstaff.
The data indicate that five to seven hawksbills successfully nested on this stretch of beach each
year. Assuming a 2-3 year nesting remigration interval (Antigua: Corliss et al., 1990), an
estimated 15 different females nested over the three year period. The site does, therefore, seem a
good candidate for an intensive tagging study to determine the exact number of nesting females,
as well as their nest site fidelity, nest fate, and inter-nesting and re-migration intervals (section
4.293). Long-term study of this "index beach" is considered vital to any successful effort to
evaluate trends in sea turtle nesting activity in Barbados.
Based on stock monitoring efforts to date, as described above, it is unlikely that the
annual nesting population of hawksbill sea turtles exceeds 50 individuals. The importance of the
national volunteer effort is clear, and continued participation will be encouraged. In addition, a
comprehensive multi-year, island-wide survey should be undertaken as soon as possible in order
to further define essential habitat, monitor trends in nesting numbers and hatch success, identify
significant threats to nesting and hatching sea turtles, and refine estimates of the proportion of
nesting activity actually reported by the public each year (see also section 4.112).
Page 28
4.292 Hatchlings
Data on nesting (natural and relocated) and hatching activities are compiled at Bellairs
Research Institute. The fates of most nests are monitored; nest contents are examined after an
incubation period of 60-65 days. This allows an estimate to be made of hatching success in
different months and on different coasts (see Horrocks and Scott, 1991) and gives an indication
of causes of mortality within the nest. If resources become available, a more in-depth study of
the susceptibility of embryos at different ages to various mortality factors in the nest would be
useful. Bellairs Research Institute is alerted to any episodes of hatchling disorientation by
artificial lighting and records the probable cause of mortality in the case of disoriented
hatchlings; e.g., crab depredation, dehydration. A sub-sample of living disoriented hatchlings
from each nest are measured (SCL and CW) before releasing them.