Clutch Frequency of the Michoacán Green Seaturtle

Alvarado-Dí­az, Javier; Arias-Cóyotl, Ethel; Delgado-Trejo, Carlos

doi:10.1670/0022-1511(2003)037[0183:cfotmn]2.0.co;2

Cited by 13 publications

(14 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The number of green turtles estimated through tagging and recapture during the 1996/1997 season qualifies Bioko as the second most important nesting area for this species along the Atlantic coast of Africa, after the rookery of Guinea Bissau (Catry et al 2002). We feel that this estimate is robust as: (1) close to 100% of successful nests were recorded, and (2) although beach surveys typically under-estimate clutch frequency (Tucker 2010) our estimated ECF is similar to the one reported in other green turtle nesting studies elsewhere (reviewed by Hirth 1997;Broderick et al 2002;Alvarado-Diaz et al 2003). Following the fieldwork supervised by the author (JT), no systematic surveys were undertaken for two nesting seasons before the work of Rader et al (2006) where a similar methodology was used although there was no resident specialist collating and quality assuring data.…”

Section: Importance Of the Site For Sea Turtle Conservation In Africasupporting

confidence: 79%

Bioko: critically important nesting habitat for sea turtles of West Africa

Tòmàs

Godley

Castroviejo³

et al. 2010

Biodivers Conserv

View full text Add to dashboard Cite

We evaluate the conservation status and threats faced by sea turtle nesting populations at Bioko Island, Equatorial Guinea (Central Africa). Beaches were monitored to obtain a detailed sea turtle nest census and, where possible, tagging of adult females was undertaken. Four sea turtle species were found nesting in the area: the green turtle (Chelonia mydas), the leatherback (Dermochelys coriacea), the olive ridley (Lepidochelys olivacea) and the hawksbill (Eretmochelys imbricata); with the former two species nesting in regionally important numbers. Nesting activity was concentrated between November and February, with a peak in December-January. Tagging and recapture of green turtles in two consecutive seasons suggested an estimated 560 (interquartile range: 420-1,681) and 414 (interquartile range: 190-1,255) nesting females in the area, respectively. Estimated numbers of nesting leatherbacks ranged from 123 to 215 and 243 to 293 in the first and second season, respectively. The other two species were less abundant (olive ridley: 19-29 and 28-43; hawksbill: 4-10 and 2 turtles). Data were compared with more recent surveys in the area and contextualised with information on human related threats. Despite the size of nesting stocks, ongoing permitted and illegal take of adult turtles at the nesting site constitutes a serious threat for these breeding aggregations. Additionally, tag returns from throughout the Gulf of Guinea suggest that the level of take in regional fisheries may also be a major threat.

show abstract

Section: Importance Of the Site For Sea Turtle Conservation In Africasupporting

confidence: 79%

Bioko: critically important nesting habitat for sea turtles of West Africa

Tòmàs

Godley

Castroviejo³

et al. 2010

Biodivers Conserv

View full text Add to dashboard Cite

show abstract

“…Mean OIP reported for green turtles is ~13 days (range 12–15 days, Hirth ), and mean OIP previously reported for green turtles in Santa Rosa National Park (Cornelius ) and Mexico (Alvarado‐Díaz et al . ) was 12 days. The average OIP in Cabuyal was ~2 days longer (15.4 days) than the reported mean for the species.…”

Section: Discussionmentioning

confidence: 97%

Nesting ecology of East Pacific green turtles at Playa Cabuyal, Gulf of Papagayo, Costa Rica

et al. 2014

View full text Add to dashboard Cite

East Pacific green turtles (Chelonia mydas), often referred to as black turtles, are smaller and exhibit a lower reproductive output than other populations of green turtles in the Atlantic, Indian and Western Pacific Oceans. Knowledge of nesting ecology of East Pacific green turtles is limited to general descriptions. We conducted an exhaustive analysis of the nesting ecology of East Pacific green turtles at Playa Cabuyal, North Pacific Costa Rica. Compared with other populations of green turtles, East Pacific turtles exhibited smaller clutch sizes (mean ± SD: 76.9 ± 18.2 eggs per clutch), but the number of clutches (estimated clutch frequency (ECF): 4.3 ± 2.3 clutches) fell within the upper limit reported for green turtles. Clutch size and seasonal reproductive output (409 ± 135 eggs per female), but not ECF, increased with female size. The observed internesting period (OIP) between consecutive oviposition events (mean ± SD: 15.4 ± 2.9 days) increased as the season progressed and was approximately 2 days longer than the mean OIP reported for the species. Most clutches were laid in the upper vegetated part of beach (zone 3, 75%) and within this zone, tended to be located underneath trees (79%). Hatching success of clutches laid underneath trees was significantly higher (0.89 ± 0.17) than that of clutches laid in the exposed areas of zone 3 (0.75 ± 0.33). Mean duration of the nesting process (3:14 h) was on average 45 min longer than previously reported for the species. Frequency of false crawls was high (49% of nesting activities), and nesting success was low (54% of nesting attempts). Poaching of eggs, tourism and predation by dogs were important threats to this population. Conservation actions were being successfully implemented at the local level due to presence of beach patrollers, but official protection is needed for the preservation of the nesting population into the future.

show abstract

“…The underestimation of these values could affect conservation strategies by overestimating the number of females in a population where number of females is estimated by number of nests. Alvarado-Díaz et al (2003) calculated the number of females nesting per year based on OCF ¼ 2.5 and compared it to the number of females nesting per year obtained by estimating it with ECF ¼ 3.1. As a result, the calculated number of females in the population was lower with a greater clutch frequency given the same number of nests.…”

Section: Discussionmentioning

confidence: 99%

“…For green turtles, clutch frequency in the Atlantic has been reported to be as high as 6 clutches per season (Bjorndal et al 1999). However, a conspecific, the East Pacific green turtle, is reported to have a clutch frequency of 3 or less for a nesting season (Alvarado-Díaz et al 2003). Even though previous research provides information about estimated number of clutches for all sea turtle species, such information is limited because of incomplete coverage of nesting areas, loss of tags, and loss of individual turtles due to occasional lack of fidelity to nesting beaches (Miller 1997).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Reproductive output and ultrasonography of an endangered population of East Pacific green turtles

Blanco

Morreale

Vélez³

et al. 2011

J Wildl Manag

View full text Add to dashboard Cite

Reproductive output is one of the most relevant aspects of life history. We analyzed the reproductive output of the endangered East Pacific green turtle (Chelonia mydas) nesting in Nombre de Jesús, Costa Rica. We supplemented beach patrols with ultrasonography to estimate clutch frequency. With ultrasound scans, we classified the stage of turtle ovaries as: early stage (2 or more clutches), late stage (1 clutch), and depleted ovaries (no clutches). We calculated mean (±SD) estimated clutch frequency (ECF) to be 3.7 ± 1.8 (n = 24) and an adjusted frequency considering individual stage (ECFU; ECF + number of clutches remaining as observed in the last ultrasound) as 5.1 ± 1.3. This is greater than previously described for East Pacific green turtles. Greater individual output could be representative of a healthier population; but could also indicate a decrease in the estimate population numbers previously reported. © 2011 The Wildlife Society.

show abstract

Clutch Frequency of the Michoacán Green Seaturtle

Cited by 13 publications

References 3 publications

Bioko: critically important nesting habitat for sea turtles of West Africa

Bioko: critically important nesting habitat for sea turtles of West Africa

Nesting ecology of East Pacific green turtles at Playa Cabuyal, Gulf of Papagayo, Costa Rica

Reproductive output and ultrasonography of an endangered population of East Pacific green turtles

Contact Info

Product

Resources

About