Nesting by hawksbill sea turtles Eretmochelys imbricata in Barbados, West Indies, has been monitored since 1992. Data from the index beach indicate that the number of nests may have increased as much as 8-fold over this period. The estimated abundance of nesting females on Barbados is 1250, suggesting that this eastern Caribbean island now hosts one of the largest rookeries in the wider Caribbean, with over 230 females nesting on the index beach alone. Given its extreme easterly position and the prevailing north-westerly current flow into the Caribbean Sea, Barbados is likely to be a significant contributor to foraging grounds throughout the region. Primary females, which are untagged and without tag scars, made up the majority of females encountered on nesting beaches in most years, suggesting that reductions in juvenile and sub-adult mortality, both nationally and regionally, are significant to the increase in number of nesting females. Females nest every 2.47 yr on average, although remigration intervals of individual females vary (range: 1 to 6 yr), suggesting environmental influences on nesting periodicity. The average clutch frequency estimated from the index beach was 4.1 nests per female, but that calculated from less intensively surveyed beaches was lower. Primary and Remigrant females differed in length, mass and clutch frequency; the results must be viewed with caution, however, as preliminary laparoscopic examinations revealed that some Primary females were not in fact nesting for their first season, and because differences in nest site fidelity between the 2 groups of females could potentially cause the differences in clutch frequencies estimated.

Somatic growth dynamics are an integrated response to environmental conditions. Hawksbill sea turtles (Eretmochelys imbricata) are long‐lived, major consumers in coral reef habitats that move over broad geographic areas (hundreds to thousands of kilometers). We evaluated spatio‐temporal effects on hawksbill growth dynamics over a 33‐yr period and 24 study sites throughout the West Atlantic and explored relationships between growth dynamics and climate indices. We compiled the largest ever data set on somatic growth rates for hawksbills – 3541 growth increments from 1980 to 2013. Using generalized additive mixed model analyses, we evaluated 10 covariates, including spatial and temporal variation, that could affect growth rates. Growth rates throughout the region responded similarly over space and time. The lack of a spatial effect or spatio‐temporal interaction and the very strong temporal effect reveal that growth rates in West Atlantic hawksbills are likely driven by region‐wide forces. Between 1997 and 2013, mean growth rates declined significantly and steadily by 18%. Regional climate indices have significant relationships with annual growth rates with 0‐ or 1‐yr lags: positive with the Multivariate El Niño Southern Oscillation Index (correlation = 0.99) and negative with Caribbean sea surface temperature (correlation = −0.85). Declines in growth rates between 1997 and 2013 throughout the West Atlantic most likely resulted from warming waters through indirect negative effects on foraging resources of hawksbills. These climatic influences are complex. With increasing temperatures, trajectories of decline of coral cover and availability in reef habitats of major prey species of hawksbills are not parallel. Knowledge of how choice of foraging habitats, prey selection, and prey abundance are affected by warming water temperatures is needed to understand how climate change will affect productivity of consumers that live in association with coral reefs.

A generalized additive mixed modelling approach was used to investigate the somatic growth of hawksbill turtles Eretmochelys imbricata (23.7 to 80 cm curved carapace length [CCL]) on nearshore coral reef sites around Barbados at depths of 12 to 35 m. The effects of body size, sex, sampling year, recapture interval and an indicator of foraging habitat quality on growth rates were investigated. The model accounted for about 60% of the variance in growth rates, but only mean size and sampling year were significant predictors. The growth rate function was nonmonotonic, with peak growth (3.4 cm yr -1 ) occurring in turtles with a CCL between 30 and 35 cm. The lower growth rates recorded for smaller turtles may reflect a period when sea turtles newly recruiting from pelagic to neritic habitats are adapting to a change in diet. The decline in growth rates with sampling year over the 10 yr study may reflect density-dependent effects on growth. Declining growth rates may prompt large juveniles to leave the Barbados foraging ground to settle elsewhere to grow to maturity.KEY WORDS: Eretmochelys imbricata · Growth rate modelling · Barbados · Developmental habitat · Foraging ground · Density-dependent effect · Generalized additive mixed model Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 432: [269][270][271][272][273][274][275][276] 2011 Measurement of somatic growth rates of juvenile sea turtles is a prerequisite for assessment of life-stage durations and age to maturity, and has inevitably focused on the more accessible benthic feeding-phase size classes (but see Bjorndal et al. 2003). To date, modelling of growth has focused on loggerheads (e.g. Bjorndal & Bolten 1988a, Bjorndal et al. 1994, 2003, Chaloupka et al. 2004, Braun-McNeill et al. 2008) and green turtles (e.g. Bjorndal & Bolten 1988b, Limpus & Chaloupka 1997, Bjorndal et al. 2000, Balazs & Chaloupka 2004, Kubis et al. 2009). Growth rate data for juvenile hawksbills have been reported from the US Virgin Islands (Boulon 1994), the Dominican Republic (León & Diez 1999), Puerto Rico (Diez & van Dam 2002), the Bahamas (Bjorndal & Bolten 2010), and the Cayman Islands (Blumenthal et al. 2009a) in the Caribbean region, as well as from Australia (Chaloupka & Limpus 1997, Whiting & Guinea 1998 and Aldabra (Indian Ocean) (Mortimer et al. 2003). Interpretation of growth patterns in several of these studies has, however, been hampered by small sample sizes and short recapture intervals (i.e. <1 yr).A number of factors affect growth rates of juvenile green and loggerhead turtles. Variability has been attributed to habitat type (Balazs & Chaloupka 2004, Kubis et al. 2009, Bjorndal & Bolten 2010, population density (Bjorndal et al. 2000, Balazs & Chaloupka 2004, Kubis et al. 2009), and water temperature (Gibbons et al. 1981), as well as to stock-specific (Seminoff et al. 2002), age-specific (Bjorndal et al. 2003) and sexspecific factors (Chaloupka et al. 2004). León & Diez (1999) and Diez & van Dam (2002) foun...

Because species respond differently to habitat boundaries and spatial overlap affects encounter rates, edge responses should be strong determinants of spatial patterns of species interactions. In the Caribbean, mongooses (Herpestes javanicus) prey on hawksbill sea turtle (Eretmochelys imbricata) eggs. Turtles nest in both open sand and vegetation patches, with a peak in nest abundance near the boundary between the two microhabitats; mongooses rarely leave vegetation. Using both artificial nests and hawksbill nesting data, we examined how the edge responses of these species predict the spatial patterns of nest mortality. Predation risk was strongly related to mongoose abundance but was not affected by nest density or habitat type. The product of predator and prey edge response functions accurately described the observed pattern of total prey mortality. Hawksbill preference for vegetation edge becomes an ecological trap in the presence of mongooses. This is the first study to predict patterns of predation directly from continuous edge response functions of interacting species, establishing a link between models of edge response and species interactions.

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