Loggerhead nesting trend in three beaches of Boavista, Cape Verde archipelago

[EN] Nesting beach surveys are the most widely implemented monitoring tool in use by the global sea turtle community and are an important component of a comprehensive program to assess and monitor the status of sea turtle populations. These assessments are necessary to evaluate the effects of recovery and conservation activities that are being implemented at all life history stages. Monitoring techniques employed on nesting beaches range from highly structured standardized sampling to “snapshots” of nesting activity within a nesting season. Very long-term nest counts data (more than twenty years) were analyzed for some turtle populations.

Temporary sequences and description of the emergency of newborns loggerhead in the Cape Verde archipelago

[EN] Sea turtles bury their eggs in the sand of the beach, where they incuba te. After a period of approximately two months, hatchlings break the eggshell and remain inside the chamber for three to seven days (Hays & Speakman, 1993). Then they leave the nest and emerge to the surface of the beach, going quickly towards the surf, to begin their pelagic and developmental stage (e.g., López-Jurado & Andreu, 1998). Hatchlings usually do not emerge from the nest as a single group. They emerge in groups at different moments, resulting in more than one emergence per nest during sorne days (Whitherington et al.,4 1990; Hays et al., 1992; Peters et al., 1994).

Comparative study of the epibionts on the pelagic and mature female loggerhead turtles on the Canary and Cape Verde islands

[EN] Marine turtles commonly carry diverse forms of epizoa on their shells. The occurrence of a particular species may ultimately help to clarify certain questions about sea turtle natural life history. This paper gives a detailed and comparative list of epizoic species found on two populations of macaronesian loggerheads: pelagic and juveniles living around the Canary Islands and mature females nesting in Boavista Island, Cabo Verde. For the epizoic flora, the most important genera founded is Polysiphonia (Rhodophiceae); P. carettia for the pelagics and Polysiphonia sp. for the nesting animals.

High plasticity of loggerhead nesting site fidelity: from using repeatedly the same small beach during different seasons to deposit consecutive nests in different islands distant more than 100 km

[EN] Sea turtles exhibit a strong natal homing associated with a high nesting site philopatry. Mark-recapture and genetic studies confirm these patterns suggesting differences among and within species. In the present study, we have analysed the degree of nest site fidelity of a loggerhead population nesting on the islands of Cape Verde and have evaluated the existence of intrapopulational variability in this trait. The loggerhead is the only sea turtle species that nests in Cape Verde, and 15,000–25,000 nests per season have been estimated for the whole archipelago.

Loggerhead nesting trend in three beaches of Boavista, Cape Verde archipelago

[EN] Nesting beach surveys are the most widely implemented monitoring tool in use by the global sea turtle community and are an important component of a comprehensive program to assess and monitor the status of sea turtle populations. These assessments are necessary to evaluate the effects of recovery and conservation activities that are being implemented at all life history stages. Monitoring techniques employed on nesting beaches range from highly structured standardized sampling to “snapshots” of nesting activity within a nesting season. Very long-term nest counts data (more than twenty years) were analyzed for some turtle populations.

The size of the loggerhead nesting females in the Cape Verde islands

[EN] The recently discovered nesting colony of Caretta caretta at the island ofBoavista (Cape Verde Islands, West Africa, FIGURE 1) is being subject ofresearch since 1998. A total number of 1,391 different females have been tagged during the 1998, 1999 and 2000 nesting seasons. Although more data are needed, these islands may represent one ofthe most important populations for the species in the North Atlantic (Brongersma, 1982; Ross, 1995; López-Jurado & Andreu, 1998). The present study shows a comparative analysis between the morphometric data collected at Boavista during the last 2000 nesting season and those recorded in the 1998 and 1999 seasons. These data have also been contrasted with those from other loggerhead nesting populations around the world for possible differences.

Pathogenic effect of microorganisms on loggerhead eggs

[EN] Different types of fungi and bacteria have been isolated from hatched and non-hatched as well as failed and non-failed eggs in natural sea turtles nests (Marco et al. 2006, Phillott and Parmenter, 2001, Phillott et al. 2001). Microbiota infections are common in artificial incubation activities and they seem to have an important negative impact on embryo development (Phillott, 2002). However, no clear evidences of their pathogenic effects have been described. The aim of this study was to investigate whether fungi and bacteria represent pathogenic agents to sea turtle eggs, and to assess whether there exists a specific period during incubation in which eggs are more susceptible to microorganisms.

Effects of light pollution by car headlights on loggerhead hatchlings in Cape Verde

[EN] Many sea turtle nesting areas are experiencing a tremendous growth in tourism during the last decades that will likely continue in the near future. Many touristic activities involve light pollution by the increasing presence of vehicles close or even over the beaches. Vehicles can drive towards or along the beaches and even stay with the lights turned on illuminating during prolonged periods of time significant zones with sea turtle nesting activity. Thus, it is important to evaluate the impact of car light pollution on both nesting females and newborns in their search of the sea.

Experimental study about the impact of artificial lighting on loggerhead female nesting in Cape Verde.

[EN] Artificial illumination of nesting beaches is one of the main threats to endangered sea turtle populations. Nocturnal lighting can impair female nest site selection and nesting success, as well as behavior and hatchling survival in their way from the nest surface to the seashore. The island of Boavista (Cape Verde) hosts the third largest loggerhead nesting aggregation in the world and the only relevant population in the Eastern Atlantic coast. Several threats such as fishing by-catch and female slaughter during nesting are severely threatening its conservation.

Influence of loggerhead egg agregation on survival: why does single eggs buried into natural sand dye in few days?

[EN] The incubation is an essential life period for oviparous species that very often experiences a high mortality. In some reptile species the number of eggs that develop together in the incubation chamber affects survival and hatchling phenotype. Sea turtle eggs develop in underground locations on sandy beaches in large masses that usually have more than 80 eggs. Natural egg mortality seems to vary among species and for the sensitive leatherbacks, external eggs seems to survive better than internal ones within the nest.

Phenotypically linked dichotomy in sea turtle foraging requires multiple conservation approaches

[EN] Marine turtles undergo dramatic ontogenic changes in body size and behavior, with the loggerhead sea turtle, Caretta caretta, typically switching from an initial oceanic juvenile stage to one in the neritic, where maturation is reached and breeding migrations are subsequently undertaken every 2-3 years [1-3]. Using satellite tracking, we investigated the migratory movements of adult females from one of the world's largest nesting aggregations at Cape Verde, West Africa. In direct contrast with the accepted life-history model for this species [4], results reveal two distinct adult foraging strategies that appear to be linked to body size. The larger turtles (n = 3) foraged in coastal waters, whereas smaller individuals (n = 7) foraged oceanically.