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.

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.

Biología reproductora de la tortuga boba (Caretta caretta Linneo, 1758) en la isla de Boavista, archipiélago de Cabo Verde

[ES]Este trabajo analiza diversos aspectos de la biología reproductora de la población nidificante de tortuga boba (Caretta caretta) en el archipiélago de Cabo Verde. Se estudiaron datos relacionados con la temporada de anidación, con la morfometría de las hembras, con el éxito de las salidas a tierra, con el tiempo de incubación y con el éxito de los nidos.

Satellite tracking of adult loggerheads (Caretta caretta L.) around waters of Cape Verde Archipielago (Western Africa)

[EN] During the 1999 nesting season (from June to October), four satellite transmitters were attached to two males and two females of Caretta caretta from Boavista Island (Cape Verde Archipelago, western Africa), where density of nesting females is the highest in the whole archipelago. Transmitters did not work as well as expected, resulting in a low number of locations, possibly due to the neritic behavior of adult loggerheads at reproductive habitat, with the antennae exposed to continuous rubbing. Therefore, we establish a conservative hypothesis about movements of C.caretta in Cape Verde.

Productivity of females loggerhead from Cabo Verde Islands

[EN] The nesting colony of Caretta caretta has been recently described for the island of Boavista (Cabo Verde, 500 km off the coast of Senegal, Western Africa, FIGURE 1). Although more data is needed, it represents one of the most important populations in the North Atlantic (Brongersma, 1982; López-Jurado & Andreu, 1998; Ross, 1995). Since 1998, a tagging and management campaign was established in Boavista to study this nesting population. We present next data on reproductive biology of nesting females of Caretta caretta in Boavista during the year 2000 nesting season, in which we obtained twice as much than those tagged in 1998 and 1999 seasons; we also found some recaptures of females from preceding years, our first data on remigration interval.

Manual for the monitoring of sea turtles in the Cape Verde Islands

[ES] To actively protect sea turtles on their nesting beaches, it is essential to obtain knowledge about trends in abundance. The way sea turtles live makes it extremely difficult to identify how many individuals there are in a population at any point in time. Due to practical problems, given their entirely marine life with limited visibility and great oceanic dispersal, counting males or juveniles is currently quite difficult and imprecise. Counting females and nests on beaches during the nesting season is the best feasible but still imperfect method, since only an unknown portion of adult females nest every season. It is impossible to know the real number of females in the population by merely counting females and nests in a given year.

Injuries observed in nesting females of loggerhead turtles on Boavista island (Cabo Verde Archipelago)

[EN] Different kinds of physical anomalies are frequently observed in any sea turtle breeding population. Nesting beaches are an excellent place to study the injuries and defects that occur in adult females. The archipelago of Cape Verde is situated about 500 km of Senegal, West Africa. Boavista is the eastern most island and may constitute the most important nesting area for the loggerhead turtle in the archipelago. The studies conducted from 1998 to 2004 indicate that Cape Verde might account for one of the most important loggerheads populations in the eastern Atlantic. The nesting females in Boavista were surveyed during the 2004 season, in order to (1) know the health status of the population (2) determine the effects of physical anomalies on nesting behaviour and (3) determine the possible origin of the injuries observed.

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.

Injuries observed in nesting females of loggerhead turtles on Boavista island (Cabo Verde Archipelago)

[EN] Different kinds of physical anomalies are frequently observed in any sea turtle breeding population. Nesting beaches are an excellent place to study the injuries and defects that occur in adult females. The archipelago of Cape Verde is situated about 500 km of Senegal, West Africa. Boavista is the eastern most island and may constitute the most important nesting area for the loggerhead turtle in the archipelago. The studies conducted from 1998 to 2004 indicate that Cape Verde might account for one of the most important loggerheads populations in the eastern Atlantic. The nesting females in Boavista were surveyed during the 2004 season, in order to (1) know the health status of the population (2) determine the effects of physical anomalies on nesting behaviour and (3) determine the possible origin of the injuries observed.

Preliminary approach to the hatchlings sex-ratio of a population of Caretta caretta of Boavista island, Cape Verde Archipielago (Western Africa).

[EN] A nesting population of loggerhead sea turtles Caretta caretta has recently been described for Boa Vista Island, Cape Verde Archipelago (Western Africa). Since 1998, “Projecto Cabo Verde Natura 2000” has monitored three beaches during the turtle breeding season. The beaches being monitored - Calheta, Errata and Ponta Cosme - are located in the southeast part of Boa Vista Island. This work intends to give a first insight into the Boa Vista Island sea turtle population’s sex ratio using a histological approach, as sexual determination in sea turtles is known to be temperature-dependent (TSD or temperature-dependent sex determination).

Monitoring and conservation of the largest loggerhead turtle (Caretta caretta) nesting population in Africa: successes and challenges.

[EN] The Republic of Cape Verde is situated about 500 km off the coast of Senegal, West Africa. The islands of Sal, Boa Vista and Maio constitute the Eastern group and harbour the most important nesting beaches for loggerhead turtles in the Archipelago. During 1998-2004 nesting seasons, fieldwork has been focused on the eastern beaches of Boa Vista and, occasionally, in other beaches of Boa Vista and in the islands of Maio, Sal and Santa Luzia. The main study area includes a total extension of 3.1 km of suitable nesting beaches. All through these years, a tagging program has been carried out, alongside recording of biological data and monitoring of nests.

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.

Genetic characterization of hawksbill juveniles foraging at Cape Verde islands indicates major undiscovered nesting populations in the region

[EN] The hawksbill sea turtle (Eretmochelys imbricata) is a circumglobal tropical species listed as Critically Endangered by the IUCN. While it is known that at least one stock occurs around the rookeries of São Tome and Principe and Bioko Islands, the eastern Atlantic remains genetically unexplored. We present the first analysis of mitochondrial DNA (mtDNA) sequences (n = 28) of hawksbill juveniles in a foraging aggregation at the Cape Verde Islands, an archipelago located in the eastern Atlantic. The mean size (minimun curve carapace length) of the studied individuals was 42.45 cm.