Do wire cages protect sea turtles from foot traffic and mammalian predators?

Published source details Mroziak M.L., Salmon M. & Rusenko K. (2000) Do wire cages protect sea turtles from foot traffic and mammalian predators?. Chelonian Conservation and Biology, 3, 693-698.
Share Tweet Email

Actions

This study is summarised as evidence for the following.

	Action	Category
	Use nest covers to protect against human disturbance Action Link
	Protect nests and nesting sites from predation using artificial nest covers: Sea turtles Action Link

Use nest covers to protect against human disturbance

A replicated, controlled, paired study in 1996 in beaches in Florida, USA (Mroziak et al. 2000) found that covering loggerhead Caretta caretta turtle nests with individual cages did not improve hatching success in areas with high or low human footfall. Hatching success was similar between caged and uncaged nests in areas of high footfall (caged: 66–67%, uncaged: 66–71%) and low footfall (caged: 75–76%, uncaged: 66–76%). In May–October 1996, fifty-eight paired sea turtle nests were either uncovered or covered with square wire cages (76 cm square, 107 cm tall, 5 x 10 cm mesh) anchored 30 cm in the sand in both low (66 total nests, 4,209 caged eggs, 3,888 uncaged eggs, 20 beach users/hour, two beach zones) and high traffic beaches (50 total nests, 3,678 caged eggs, 4,991 uncaged eggs, 50 beach users/hour, two beach zones. Hatching success was determined by excavating nests three days after hatchlings emerged to count successfully hatched eggs.

(Summarised by: Katie Sainsbury)
Protect nests and nesting sites from predation using artificial nest covers: Sea turtles

A replicated, controlled, paired study in 1996 on a beach in Florida, USA (Mroziak et al. 2000) found that loggerhead Caretta caretta turtle nests covered with cages had higher predation rates compared to uncovered nests. Caged sea turtle nests had higher predation rates (high predation beach sections: 42–47% nests predated, low predation beach sections: 15–22%) compared to uncaged nests (3–4% and 0–3% respectively). Approximately one third of predated nests were completely destroyed whether nests were caged (11 of 29 nests) or uncaged (1 of 3 nests). Decoy cages (with no nests) were predated in high and low predation beach sections (high: 10 of 18 nests, low: 6 of 14 nests), in some cases multiple times (high: 7 of 10 nests predated >once, low: 2). Hatchling numbers from unpredated caged or uncaged nests were similar (80 hatchlings/nest) and higher than hatchling numbers from partially predated nests (50 hatchlings). Racoons Procyon lotor caused 88% of predation, grey foxes Urocyon cinereoargenteus 11% and spotted skunks Spilogale putorius 1%. In May–October 1996, sea turtle nests were covered with square wire cages (76 cm square, 107 cm tall, 5 x 10 cm mesh) anchored 30 cm in the sand or left uncovered in pairs in two low (40 nest pairs) and two high predation beach sections (50 nest pairs). Nest pairs were laid within 2 days of each other and in their natural position (<15 m apart, 53 pairs) or relocated to create a pair (>4 m apart, 37 pairs). Thirty-two decoy cages not covering actual nests were placed on the beach (high predation: 18 cages; low predation: 14). All nests (including decoys) were checked daily for signs of predation until October and the likely identity of the predator. Nests were excavated three days after emergence to count successfully hatched eggs.

(Summarised by: Katie Sainsbury)