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Sexual Dimorphism and Foraging Trips of the Laysan Albatross (Phoebastria immutabilis) on Guadalupe Island

1
Centro de Investigaciones Biológicas del Noroeste (CIBNOR), La Paz 23090, Baja California Sur, Mexico
2
Grupo de Ecología y Conservación de Islas (GECI), Ensenada 22800, Baja California, Mexico
3
Cornell Laboratory of Ornithology, Ithaca, NY 14850, USA
*
Author to whom correspondence should be addressed.
Animals 2019, 9(6), 364; https://doi.org/10.3390/ani9060364
Received: 26 March 2019 / Revised: 20 May 2019 / Accepted: 28 May 2019 / Published: 17 June 2019
(This article belongs to the Section Wildlife)
We evaluated the existence of sexual dimorphism in Laysan albatross from Guadalupe Island. Males were larger than females across all the morphological variables analyzed. We created a sex predictor model for Laysan albatross individuals that requires a minimum number of input variables and will considerably reduce the handling times and field costs of future studies. Laysan albatross foraging trips were recorded during their breeding season over multiple years and no significant differences were found between the distances travelled by males versus females.
Sexual dimorphism in the Laysan albatross (Phoebastria immutabilis) on Guadalupe Island was evaluated during the breeding seasons of 2015–2018 by measuring and comparing 10 morphological attributes: cranial length, bill length, nostril length, cranial width, bill height, bill width, tarsus length, closed wing length, opened wing length, and wingspan length in reproductive adults (n = 135). Males were larger than females across all traits (Student’s t-test, p < 0.05, p < 0.05). We created a logistic model using stepwise regression to predict sex based on morphological variables. This model indicated four significant morphological predictor variables (z < 0.05) and was able to successfully predict the sex of P. immutabilis individuals in more than 90% of the cases. Based on these predictor variables, a web app was developed to determine the sex of the Laysan albatross in the field, providing a non-invasive method for rapid data collection that reduces costs and handling times while improving conservation efforts. We tracked Laysan albatross (n = 36) during breeding seasons and found no significant differences between females and males for either trip length (GLMM, F = 0.017, DF = 1, 1, p = 0.917 > 0.05) or maximum trip distance (GLMM, F = 0.374, DF = 1, 1, p = 0.651 > 0.05). Our results suggest that both sexes show a strong preference to travel to highly productive coastal waters northeast of the breeding colony that are influenced by the California Current. The present research will serve to establish a baseline to protect this species on Guadalupe Island and highlights the importance of understanding sexual dimorphism in at-risk seabird species. View Full-Text
Keywords: Laysan albatross; Guadalupe Island; sexual dimorphism; foraging trips Laysan albatross; Guadalupe Island; sexual dimorphism; foraging trips
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Hernández Montoya, J.C.; Juárez-Rodríguez, M.; Méndez-Sánchez, F.; Aguirre-Muñoz, A.; Rojas-Mayoral, E.; Íñigo-Elias, E.; Galina-Tessaro, P.; Arnaud, G.; Ortega-Rubio, A. Sexual Dimorphism and Foraging Trips of the Laysan Albatross (Phoebastria immutabilis) on Guadalupe Island. Animals 2019, 9, 364.

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