The Sea Turtle Rookery at Gnaraloo Bay, Western Australia: Using Nocturnal Observations to Validate Diurnal Track Interpretations

Thomson, Jordan A.; Hajnoczky, Nora; Hattingh, Karen
December 2016
Chelonian Conservation & Biology;Dec2016, Vol. 15 Issue 2, p187
Academic Journal
Critical gaps remain in our understanding of many sea turtle nesting aggregations in remote or undeveloped regions. Here, we summarize the first 8 yrs of systematic monitoring of the rookery at Gnaraloo Bay, Western Australia. Diurnal track surveys on this approximately 7-km mainland beach were conducted daily during nesting seasons 2008/09 to 2015/16. The total number of emergences (i.e., nests and failed nesting attempts) recorded per season ranged from 480 to 813 (mean = 679.0, SE = 49.1), whereas the number of nests ranged from 305 to 522 (mean = 376.0, SE = 26.7). Peak nesting activity occurred between mid-December and late January, with approximately 70 emergences and 35 nests recorded on average per week during this time. The majority (97%) of emergences and nests were from loggerhead turtles ( Caretta caretta), whereas the remainder (3%) were from green turtles ( Chelonia mydas). The number of loggerhead turtle emergences recorded per season declined significantly over the course of the study, wheras the number of nests did not, although we suspect that nest detection errors contributed to the difference between trends. We conducted nocturnal surveys (i.e., direct observations) during parts of seasons 2010/11 to 2015/16 to validate diurnal track interpretations and assess potential biases in the diurnal data set. Diurnal nest counts for loggerhead turtles were underestimates in all seasons but one, with an average nest detection bias of −13.0% (SE = 3.0). After accounting for this bias, we estimate that approximately 405 nests are dug by 85 female loggerhead turtles in the Gnaraloo Bay survey area annually. A similar or slightly lower amount of loggerhead turtle nesting activity occurs at the Cape Farquhar survey area, also located on the Gnaraloo coast; thus, this region contains previously underreported nesting aggregations of this species. The Gnaraloo rookeries may play an important role in the dynamics of the southeast Indian Ocean loggerhead turtle subpopulation and may still be depleted relative to historic levels due to historical predation by introduced foxes. Monitoring, research, and the protection of Gnaraloo beaches are, therefore, critical at this juncture.


Related Articles

  • Status of Marine Turtles in the Gulf of Mannar, India. BHUPATHY, SUBRAMANIAN; SARAVANAN, SHANMUGAM // Chelonian Conservation & Biology;May2006, Vol. 5 Issue 1, p139 

    Lepidochelys olivacea was the most frequent sea turtle documented in the Gulf of Mannar during 2000–2001, whereas during the 1970s it was Chelonia mydas. Reduction in overall proportions of C. mydas and its size classes is attributed to exploitation of eggs, turtles, and incidental catch...

  • Endangered Species; File No. 16134. Payne, P. Michael // Federal Register (National Archives & Records Service, Office of;9/5/2012, Vol. 77 Issue 172, p54566 

    The article presents information that a five-year permit has been issued to Virginia Aquarium and Marine Science Center Foundation in Virginia which allows them to take several species of turtles for the purpose of scientific research. The species includes Chelonia mydas, Lepidochelys kempii,...

  • What happens to wildlife in a city that never sleeps? Jones, Therésa // Wildlife Australia;Winter2019, Vol. 56 Issue 2, p6 

    Highlights from the article: In animals, as day turns into night, diurnal (day active) species reduce their activity or go to sleep and the nocturnal (night active) animals commence the nightshift. The presence of night lighting may determine which species or which individuals within a species...

  • BOX A: SEA TURTLE CLASSIFICATION AND BIOLOGY.  // Gems & Gemology;2006, Vol. 42 Issue 1, p38 

    The article focuses on the classification of sea turtles. There are two families of contemporary marine turtles and these are Cheloniidae and the Dermochelyidae. Sea turtles with shells are classified under the Cheloniidae family. There are a total of six species categorized under this family...

  • OCEAN SUPERSTAR. MUSGRAVE, RUTH A. // National Geographic Kids;Mar2012, Issue 418, p16 

    This article offer information on several species of sea turtles. Green sea turtles have ways to remove algae, barnacles and parasites from their shells and skin. The Kemp's ridley sea turtles are quick in digging a nest compared to other species. The leatherback sea turtle measures at an...

  • Eight species of sea turtles. Kalman, Bobbie // Endangered Sea Turtles;2004, p8 

    This article focuses on the eight species of sea turtles. They are the Kemp's ridley sea turtle, the olive ridley sea turtle, the hawksbill sea turtle, the flatback sea turtle, the black sea turtle, the loggerhead sea turtle, the green sea turtle and the leatherback sea turtle. The Kemp's ridley...

  • Stopover optimization in a long-distance migrant: the role of fuel load and nocturnal take-off time in Alaskan northern wheatears (Oenanthe oenanthe). Schmaljohann, Heiko; Korner-Nievergelt, Fränzi; Naef-Daenzer, Beat; Nagel, Rolf; Maggini, Ivan; Bulte, Marc; Bairlein, Franz // Frontiers in Zoology;2013, Vol. 10 Issue 1, p1 

    Introduction: In long-distance migrants, a considerably higher proportion of time and energy is allocated to stopovers rather than to flights. Stopover duration and departure decisions affect consequently subsequent flight stages and overall speed of migration. In Arctic nocturnal songbird...

  • Swimming to oblivion. Sharpe, P. // Texas Monthly;Jun88, Vol. 16 Issue 6, p102 

    Marine scientists have struggled for ten years to establish a new colony of ridley sea turtles on South Padre Island in Texas. However, the program has yet to show results, and unless it is renewed, this summer's transfer of turtle eggs to the island will be the last. INSET: Shrimper's nets...

  • Fishing quays threaten turtles. Kumar, Sanjay // New Scientist;4/2/94, Vol. 142 Issue 1919, p7 

    Reports on the threat posed by four fishing quays to the nesting ground for olive ridley sea turtles on India's east coast. Estimated number of eggs laid by the female olive ridleys per year; Operational capacity of the quays; Estimated number of fishermen operating in one of the quays; Number...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics