Cory's Shearwater (Calonectris borealis) spatiotemporal information in the southeastern waters of Gran Canaria (Canary Islands)

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Cory's Shearwater (Calonectris borealis) spatio-temporal information in the
southeastern waters of Gran Canaria (Canary Islands)
Gustavo Tejera1 & Alejandro Delgado2
1 Canary Islands´ Ornithology and Natural History Group (GOHNIC)
2 Independent researcher
Method
Introduction
(1) Carboneras, C., Lorenzo, J.A., 2003. Pardela cenicienta Calonectris diomedea, in: (Martí, R., Del Moral, J.C.E. (Ed.), Atlas de Las Aves Reproductoras de España. SEO/BirdLife, Madrid, pp. 84–85.
(2) Reyes-González, J. M.; Zajková, Z.; Morera-Pujol, V.; De Felipe, F.; Militão, T.; Dell’Ariccia, G.; Ramos, R.; Igual, J. M.; Arcos, J. M. y González-Solís, J. 2017. Migración y ecología espacial de las
poblaciones españolas de pardela cenicienta. Monografía n.º 3 del programa Migra. SEO/BirdLife. Madrid. (3) Abramic, A., García Mendoza, A., Haroun, R., 2021. Introducing offshore wind energy in
the sea space: Canary Islands case study developed under Maritime Spatial Planning principles. Renew. Sustain. Energy Rev. 145. (4) Thomas, L., S.T. Buckland, E.A. Rexstad, J. L. Laake, S. Strind-
berg, S. L. Hedley, J. R.B. Bishop, T. A. Marques, and K. P. Burnham. 2010. Distance software: design and analysis of distance sampling surveys for estimating population size. Journal of Applied Eco-
logy 47: 5-14. DOI: 10.1111/j.1365-2664.2009.01737. (5) SEO/BirdLife, 2014. Trabajo de aves marinas durante el Proyecto LIFE + INDEMARES : Pasos hacia una red de ZEPA marinas consistente y
bien gestionada Trabajo de aves marinas durante el LIFE + Proyecto INDEMARES: Pasos hacia una red de ZEPA marinas. (6) Krüger, T., Garthe, S., 2001. Flight altitudes of coastal birds in relation to
wind direction and speed. Atl. Seabirds 3, 203–216. © Watercolour of Atlantic Shearwater: Francisco Rodríguez.
Discussion and Conclusion
Bibliography
©
Results
Canary Islands
Gran Canaria
Atlanc Ocean
• Cory's Shearwater is present in the Canary Islands between spring and autumn. These dates agree with their reproductive phenology on the islands, which
begins in March with the arrival of the bulk of the population and ends in November with the chicks leaving the burrows and leaving for southern waters (2).
• The densities recorded in the southeast of Gran Canaria are the first obtained in the waters surrounding this island. The values are similar to those obtained
in other areas of the Canary Islands (5).
• The flight height of the shearwaters is positively related to the wind intensity (6). The shearwaters rise due to the push of the wind and then descend in order
to cover greater distances, so that they manage to move with the minimum energy expenditure.
• The information generated in this work is useful to assess the potential risks of OWF on this species.
Methodology
• For data collection, censuses were carried out from a boat. The design
of the itineraries and the density analyses performed using the Distance
software, version 7.3 (4). We sampled through 57 km of zigzag
transects, covering a total area of 58 km² where three areas or group of
transects were identified: coastal, central and outer.
• The surveys were carried out from 10 am to 4 pm at a speed of about 6
-7 knots (11-13 km/h). Censuses were undertaken in eight pelagic trips
distributed through the year (two censuses per season).
• To estimate the density of shearwaters, different models were built
considering the functions that explain the loss of detectability with
distance. Akaike Information Criterion (AIC) was used to choose the
model that best fit the data and obtain the density value.
• The relationship between the flight height of the shearwaters and the
wind intensity according to the Beaufort scale was analyzed.
Study Site
The study area is located off the coast of Arinaga (Agüimes), Pozo Izquierdo
(Santa Lucía de Tirajana) and Castillo del Romeral (San Bartolomé de
Tirajana), located on the southeast of Gran Canaria (Las Palmas, Canary
Islands, Spain, Figure 1). The area has been chosen for its potential for the
installation of OWF due to the predominant wind intensity with an annual
average wind velocity of 11 m/s (3).
Data
• 225 Cory's Shearwater were detected in six of the eight censuses ca-
rried out. The species was not detected in one visit in autumn and one
in winter (from December to February).
• The density of Cory's Shearwater was similar in the three areas, with
an average value of 3.64 birds/km2 (95% CI: 2.14-6.20).
• A correlation coefficient of 0.58 between the flight height of the
shearwaters and the wind intensity was estimated. The correlation
test showed a significant association (t = 10,679, df = 224, p < 0.05),
although the regression analysis showed little predictive power (linear
coefficient of determination of 0.34, Figure 2).
Pelagic birds spend most of their lives at open sea and, therefore, their morphology is perfectly adapted to life in marine environments. Cory's Shearwater
(Calonectris borealis) is the most abundant seabird in the Canary Islands, with an estimated population of around 30,000 breeding pairs (1). The Canarian
populations of this specie carry out well-known migratory movements, which use the surface wind regime of the atmospheric circulation to reach their wintering
quarters in the waters of the South Atlantic Ocean (2).
The objectives of this work are to provide new information on the seasonality of the species in the Canary Islands, to estimate its density and to assess the
flight behavior in relation to the intensity of the wind. This information is very useful in view of the multiple installation projects for offshore wind farms (OWF)
planned off the southeastern coast of the island of Gran Canaria, following the Canary Islands sustainable energy strategy.
Figure 1. Location of the study area (southeast of Gran Canaria, Spain) sho-
wing zig-zag transects sampled by boat.
Figure 2. Relationship between flight height of the shearwaters and the wind intensity.
Jittered points are showed for handling overplotting caused by discreteness.
Pozo Izquierdo