Patrol or monitor nesting beaches
Overall effectiveness category Awaiting assessment
Number of studies: 7
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Background information and definitions
Female sea turtles are vulnerable to poaching during the nesting season. Human presence on beaches at night can prevent female sea turtles from emerging from the sea to nest or interrupt females while egg laying so that they return to sea. Once laid, nests are vulnerable to human disturbance and illegal egg collection. Patrols may be carried out at frequent intervals specifically to deter human activities. Scientific monitoring programmes may function as a similar deterrent through the regular presence of officials on a beach.
Many studies report anecdotal evidence of reduced poaching while beaches are being patrolled, but few studies actually test the effect of patrols formally.
See also: Threat: Human intrusions and disturbance – Use nest covers to protect against human disturbance.
Supporting evidence from individual studies
A study in 1981–1994 on a sandy beach in St Croix, US Virgin Islands (Boulon et al. 1996) reported that when nightly beach patrols were carried out, incidents of poaching of leatherback turtle Dermochelys coriacea nests declined. Results were not statistically tested. In 1981 when patrolling began, incidents of poaching were highest (11%); then ranged from 0–2% in 1982–1985; then remained at 0% from 1986–1994. The authors reported anecdotes that before the study began, poaching of nests approached 100% annually (no data presented). In 1981–1994 the beach was patrolled hourly between 20:00–05:00 h every night from 1 April until no new nests had been discovered for 10 days. In 1982–1994, all nests in erosion-prone areas were relocated to stable parts of the beach immediately after laying.Study and other actions tested
A study in 1991–1992 on a sandy beach in Guanacaste Province, Costa Rica (Chaves-Quirós et al. 1996) found that while a combination of periodic beach patrols for turtle nest protection; beach patrols for research; and education programmes with local communities were taking place, there was a decrease in the percentage of leatherback turtle Dermochelys coriacea nests lost to poaching. Results were not statistically tested, and the effect of the different actions cannot be separated. The percentage of nests lost to poaching was 91% (49 of 54 nests) in October when patrols began; 51% (102 of 199 nests) in November; and 0–2% (of around 500 nests) in December–March. The beach was patrolled nightly for research purposes from October 1991–March 1992. Additional patrols were carried out by rural guards for three weeks in November and December, and periodically during January and February. In October–November 1991, an education and communications programme was carried out with local communities that involved organising trips to see the turtles, the chance to help with turtle research, lectures, lessons, slideshows, and local distribution of a brochure on leatherback turtle biology and conservation. Activities were also carried out with scout groups and the National Museum of Costa Rica (dates not provided).Study and other actions tested
A before-and-after study in 1988–1997 on a beach in Playa Cuixmala, Mexico (García et al. 2003) found that after limiting human access to the beach and introducing patrols, along with moving nests to an on-beach hatchery, numbers of olive ridley Lepidochelys olivacea nests poached were lower. Results were not statistically tested. After limiting human access to the beach and introducing regular nightly beach patrols during the nesting season, two of 2,335 olive ridley turtle nests were poached in five years, compared to >90% of 59 nests poached in the two years prior to protections being introduced. A 3 km long beach was controlled by blocking human access and conducting night patrols at 3-hour intervals during the nesting season (July–March) in 1990–1997. At the same time, a proportion of nests were collected and transported to beach hatchery. Prior to this, nesting activity and poaching was monitored on the beach in 1988–1989.Study and other actions tested
A study in 1990–2004 on one sandy beach on the Caribbean coast of Costa Rica (Chacón-Chaverri et al. 2007) found that patrolling beaches resulted in a decline in poaching of leatherback turtle Dermochelys coriacea nests. Results were not statistically tested. Incidents of poaching declined over the 14-year period when beaches were patrolled, from 55% of nests poached in 1990, to 13% in 1995, 9% in 2000 and 1% in 2004. The authors reported that most poaching events took place close to public access points to the beach. In February–July 1990–2004, the beach was patrolled every night for a total of 8 h (20:00–04:00 h). The main purpose of patrols was to locate nesting female turtles and to relocate nests laid in high-risk areas to an on-beach hatchery.Study and other actions tested
A before-and-after study in 2003–2007 on three beaches on Vamizi Island, Mozambique (Garnier et al. 2012) found that a community-based turtle monitoring project appeared to reduce egg collection and hunting of adult green turtles Chelonia mydas. During the four years of a community turtle monitoring project, no egg collection (122 nests were laid/year on average) or hunting of female turtles was recorded. The authors reported that prior to the turtle monitoring project beginning, egg collection and hunting of adult female turtles was common within the local fishing community. Following the formation of two fishing village committees to manage local fishing resources and implement regulations, the committees created a turtle sanctuary around the north-east of the island to protect turtle breeding and feeding grounds. Three nesting beaches were monitored nightly for several months/year by 15 local turtle monitors supervised by a marine biologist in January–July 2003–2007.Study and other actions tested
A before-and-after, site comparison study in 2005–2012 on a beach in Costa Rica (James & Melero 2015) found that relocating olive ridley Lepidochelys olivacea turtle nests to an on-beach hatchery with 24-hour monitoring or camouflaging them on the nesting beach tended to lead to similar hatching rates and lower egg poaching rates. Results were not statistically tested. In total, 79% of nests relocated to the hatchery and of nests camouflaged on the beach successfully hatched. Egg poaching reduced from 85% in 2005 to 10% of eggs in 2005–2012. The emergence rate of hatchlings from hatchery nests was 77%, compared to 71% of hatchlings from camouflaged nests. Nesting activity was monitored by nightly beach patrols (4x 4 hours/night) in July/August–December in 2006–2012 (958 nests were laid, 98–177/year). Nests were either relocated to an on-beach hatchery (363 nests, 38%), or camouflaged (595 nests, 61%) to discourage illegal collecting. Relocated nests were randomly allocated a 1 m2 plot in the hatchery and dug into the sand. The hatchery was monitored 24 hours a day during the nesting season. Hatchlings were monitored on emergence and nests were excavated after hatching due dates to check hatching success.Study and other actions tested
A replicated, controlled study in 2008–2009 on five sandy beaches in southwest Dominican Republic (Revuelta et al. 2015) found that when beaches were patrolled regularly during the nesting season, leatherback turtle Dermochelys coriacea nest hatching success was higher than when nests were relocated for artificial incubation. Results were not statistically tested. Over two years, hatching success of nests left in situ on a beach with limited human access and regular night patrols was 74–85% compared to 34–58% for nests moved to hatcheries. Eggs were relocated from five beaches in a national park (1,374 km2). In March–August 2008–2009, the beaches were surveyed during the day and night for signs of nesting (daily – at least every other week) and nests were relocated. On beaches with high pressure of illegal collecting, 35 nests (all nests found) were relocated. On beaches with more limited human access, 31 nests were relocated and 43 were left in situ and monitored to hatching. Eggs from relocated nests were placed with sand in polystyrene boxes and moved to wooden huts near the nesting beaches. On beaches where nests were left in situ, nightly patrols were carried out by government rangers 2–3 nights/week in April–May. Beaches with all nests relocated were also patrolled regularly at night, but as all nests were removed from these beaches, no in situ results were reported.Study and other actions tested
Referenced paperRevuelta O., León Y.M., Broderick A.C., Feliz P., Godley B.J., Balbuena J.A., Mason A., Poulton K., Savoré S., Raga J.A. & Tomás J. (2015) Assessing the efficacy of direct conservation interventions: clutch protection of the leatherback marine turtle in the Dominican Republic. Oryx, 49, 677-686.
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This Action forms part of the Action Synopsis:Reptile Conservation
Reptile Conservation - Published 2021