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Seasonal and temporal-spatial distributions of green turtle (Chelonia mydas) nesting activity were assessed at Aldabra Atoll Seychelles, the second largest green turtle rookery in the Western Indian Ocean (WIO), based on morning counts of fresh turtle tracks conducted during 1980-2011. The datasets used in the analyses are derived from an average of 3-4 surveys per month at two index sites representing ~30%-42% of total annual nesting during 1980-1989 and ~58% during 1995-2011; and monthly surveys conducted at another two remote sites, which accounted for an additional 20% of annual nesting (total ~78%) during 2002-2011. Turtles engaged in year-round nesting during the season defined as December to November and characterized by patterns of high intra- and interannual variation. In some seasons, nesting peaked primarily during February to May, and in others during May to September, but on average during 1995-2011, a clear unimodal pattern emerged with nesting activity greatest during February to September, peaking during April to June, and lowest in November-December. The two Primary Index Sites situated 2.2 km apart on the west coast and separated by a lagoon entrance had mean peak nesting dates that consistently differed by more than a month. Possible explanations for the differences are discussed. At Aldabra, the timing of the 1997-1998 ENSO event coincided with a disruption in normal nesting cycles during 1998 through 2002 and the highest levels of nesting recorded at Aldabra to date during the 2000-2001 season. Comparison of seasonal median peak nesting dates at five green turtle rookeries in the WIO suggests an inverse relationship with latitude among four of them, with those in the lower latitudes peaking during the austral autumn and winter and in the higher latitudes during the austral summer, an indication that temperature may be moderating nesting seasonality in the WIO. [ABSTRACT FROM AUTHOR]

When Aldabra Atoll became a nature reserve in 1968, its endangered nesting green turtle (Chelonia mydas) population was the first to be protected in the Indian Ocean. In 1983, Aldabra became a UNESCO World Heritage Site managed by the Seychelles Islands Foundation (SIF). But prior to 1968, its green turtles suffered intense exploitation documented by trade statistics, historical literature, and a scientific study in 1927. Three population surveys conducted just before, during, and shortly after 1968 provide baseline data by which to assess the long-term population recovery monitored since 1980 using a standardized track count protocol. The 52 nesting beaches distributed along the 83-km outer rim of Aldabra were classified into 6 beach groups (WGT, SETT, DDM, DJL, CC, and North), with total beach length of 5.2 km. During Phase 1 (1980-1994) of the study, 17 index beaches (WGT #1-17) were monitored 4 times per month and other beaches opportunistically. During Phase 2 (1994-2008), index beaches (WGT #1-22 and SETT) were monitored at least 4 times per month and remote beaches monthly. Track counts were converted to estimated egg clutch production using nesting success data. Reproductive output for the atoll rose from a mean annual estimated 2000-3000 clutches in the late 1960s to 15,669 (SD = 2776) during 2004-2008, equivalent to a mean estimated 3100-5225 females nesting annually (assuming an average of 3-5 egg clutches per female). This represents a 500%-800% increase during 40 years of complete protection. During Phase 2, the rate of increase was highest at the Settlement Beach (SETT), which had historically suffered the most intense exploitation. [ABSTRACT FROM AUTHOR]

We report on data collected during the first long-term turtle monitoring and conservation program conducted in the Amirantes Islands Group of Seychelles. Green turtle (Chelonia mydas) and hawksbill (Eretmochelys imbricata) nesting activity was recorded on a daily basis, year-round, over a period of 62 months between November 2004 and December 2009 at D'Arros Island, in the context of a community-based turtle monitoring and conservation program coordinated by the D'Arros Research Centre (DRC). Green turtle nesting occurred year-round with a distinct peak in late March but also evidence of a bimodal pattern with a dominant peak during February to April and a secondary peak in July and August. For hawksbills, nesting peaked in early December, with 94.0% of nesting emergences during the four-month interval from 1 October to 31 January. Along the 5-km nesting beach, the estimated average number of clutches laid annually was 95 for green turtles (range 65-120) and 300 (range 277-318) for hawksbills. Assuming an average of 5 clutches annually for green turtles and 4-5 for hawksbills, this would represent some 20 green turtles and 60-75 hawksbill females nesting annually. This indicates an increase in nesting activity-but not necessarily in numbers of nesting females-from that reported in the early 1970s, early 1980s, and mid-1990s when exploitation was intense. During the 5 years that the DRC turtle conservation and monitoring program was underway, turtle poaching has virtually ceased at D'Arros Island and adjacent St. Joseph atoll. [ABSTRACT FROM AUTHOR]

The diving behavior of immature hawksbill turtles (Eretmochelys imbricata) was recorded by means of direct in-water observations during a period of 8 months over 4 years on a coral reef at D'Arros Island in the Seychelles. For 4 turtles that had become habituated, detailed behavioral observations were recorded and quantified during 148 contact hours during which 187 turtle dives were documented. Mean dive depth and duration were 8.2 m and 27.4 minutes, respectively. Surfacing intervals lasted on average 81.5 seconds and the mean number of breaths was 6.6 per surface interval. Dive duration was positively correlated with dive depth. On average, larger turtles conducted longer dives than smaller turtles and spent more time at the surface. Immature hawksbills at D'Arros averaged longer surface intervals and took more breaths than did those reported at other sites. We attribute this, at least in part, to the increased energy demands required to excavate cryptic food items at D'Arros. Although average foraging dives in this and other studies tended to be shallow (< 15 m) and short (< 30 minutes), the turtles are capable of significantly deeper and longer dives. We propose that immature hawksbills forage well below their physiological dive limits and do not strive to maximize their bottom times. [ABSTRACT FROM AUTHOR]