Loggerhead turtle nest site selection 155


TABLE 2 Nest scattering distance (km) in female loggerhead turtles for which at least three nesting events were observed on Maio Island, Cabo Verde, during 2012–2019.


Distance of re-nesting events (km) 0.00–0.99


1.00–4.49 4.50–14.99 15.00–52.00


No. of females (%) 169 (15.9)


323 (30.5) 327 (30.8) 241 (22.8)


10.2% and south-south-east 25.2%; χ2 = 127.09,df = 7, P,0.0001,n = 1,606; Fig. 1, Table 1). Females that changed areas between successive nests most often moved to the east coast (Fig. 1, Table 1). Analysis of recaptured females between different nesting seasons demonstrated a similar rate of re- nesting in the same area (187/286 = 65%) to recaptured females within the same nesting season (1,606/2,769 = 58%; χ2 = 3.89, df = 1,P = 0.05,n = 2).


Intra-beach nest site selection The mean width of the study zones was 11.8 ± SD 7.6 m(38.3%) for the high-risk flood zone, 6.8 ± SD 3.7 m(22%) for the medium-risk flood zone and 12.2 ± SD 4.2 m(39.6%) for the low-risk flood zone. Female loggerhead turtles did not re-nest randomly across the three flood risk zones; both those that re-nested in the same geographical area and those that changed area tended to re-nest disproportionately in the medium-risk


zone (Table 3). Re-nesting proportions differed signifi- cantly amongst the flood risk zones (same geographical area χ2 = 59.89,df = 2,P,0.0001,n = 762; different geographic- al areas χ2 = 62.45,df = 2,P,0.0001,n = 459), being lower in the high-risk zone. In contrast, the proportions of females re-nesting within the low-risk and medium-risk zones were much greater than expected (Table 3).


Discussion


Geographical distribution of nesting We conducted a comprehensive 8-year survey of individual re-nesting site selection in one of the most important logger- head turtle nesting colonies, on Maio Island, Cabo Verde (Patino-Martinez et al., 2022a). The study focused on the regional and intra-beach spatial scales. Our findings confirm that loggerhead turtles tend to have


lower beach fidelity and use broader environmental niches than other sea turtle species (Dodd, 1988;Hays&Sutherland, 1991;Pike, 2013).We found that re-nesting site selectionwithin thesamegeographicalarea(notalwaysonthe same beach) accounts for 58–65% of re-nesting events. This is consistent both within and between nesting seasons, supporting the theory of consistent inter-seasonal nest site selection (Miller, 1997). Approximately 77% of the total number of nesting femaleslaidtheir nestswithin 15 km of their previous nests.


TABLE 3 Observed and expected numbers of re-nesting events between intra-beach flooding risk sections used by loggerhead turtles on Maio Island, Cabo Verde. ‘From’ is the flood risk zone (low, medium or high) selected by females for one nesting event and ‘To’ is the location of the next nesting event. Re-nesting events within and between geographical areas are shown separately.


Flooding risk From


To Low Medium High


Medium High Low


Medium High Low


Medium High


Low Medium High


Medium High Low


Medium High Low


Medium High


Expected no. of nests


Re-nesting in the same geographical area Low


250.9 139.0 242.1 296.9 164.6 286.5 89.7 49.7 86.5


Re-nesting in a different geographical area Low


153.6 85.1


148.2 215.1 119.2 207.5 92.9 51.4 89.6


Observed no. of nests


356 222 54


303 371 74 81


110 35


190 167 30


219 244 79


103 106 25


387 542 234 181.6 210.2 105.4 2 2 2 ˂ 0.0001 ˂ 0.0001 ˂ 0.0001 n 632 748 226 χ2 239.6 416.7 104.6 df 2 2 2 P ˂ 0.0001 ˂ 0.0001 ˂ 0.0001


Oryx, 2023, 57(2), 152–159 © The Author(s), 2022. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605321001496


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