General Comparative Analysis of Bird-Bat Collisions at a Wind Power Plant in the Department of Rivas, Nicaragua, between 2014 and 2022

Abstract

From 2014 to 2022, eight monitoring campaigns have been carried out, documenting 119 collisions of birds belonging to 25 species corresponding to 14 families. Of the total collisions, 35 individuals could not be identified because only remains of the animal’s body (feathers) were found, due to the presence of day and night predators. Of the bird species identified, 17 are resident, three are migratory species, two are transient species, one species with transient populations that migrate south, and two species with both resident and migratory populations. During these years, no species with an important conservation category according to the IUCN were reported. Three species are on Nicaragua’s Red List, the migratory species Blackburnian Warbler (Setophaga fusca) and the resident species Mangrove Cuckoo (Coccyzus minor), both with the Near Threatened category; and the only migratory hummingbird for Nicaragua, the Ruby-throated Hummingbird (Archilochus colubris) with the Vulnerable category. The family with the highest frequency of collided bird species is the pigeons (Columbidae), these being very significant (X2 = 345.20, p < 0.01). The species with the highest frequency of collisions is the Common Ground-Dove (Columbina passerina) species, with these collisions being very significant (X2 = 72.05, p < 0.01). Collisions per month and year show very significant differences, especially for April 2016 (X2 = 41.60, p < 0.01). Tower T13 shows significant collisions in these eight monitoring campaigns (X2 = 36.48, p < 0.05). Bird collision distances show very significant collisions between 0 and 5 m away from the turbines (X2 = 268.96, p < 0.01). No differences were found regarding collisions between large and small birds (X2 = 2.09, p > 0.05). The granivore group presented a very significant frequency of collisions (X2 = 84.00, p < 0.01), as well as a very significant frequency of collisions in the non-passerines birds (X2 = 42.26, p < 0.01). Very significantly higher fatality frequencies were observed in 2016 (X2 = 60.16, p < 0.01). For the period 2014 to 2022 in bats, 134 collisions of bats belonging to 18 species corresponding to four families were observed. Of the total number of collisions, 24 individuals could not be identified because they were in poor condition. No species with important conservation criteria have been recorded according to the IUCN or the Nicaraguan Red List. The Molossidae family is the group with the highest number of very significant collisions (X2 = 53.61, p < 0.01), with the Pallas’s Mastiff Bat (Molossus molossus) being the one that presented very significant collisions (X2 = 199.69, p < 0.01). Very significant collisions occur, with a peak in November 2015 (X2 = 75.19, p < 0.01). Tower T15 presents the highest frequency of collisions, which is very significant (X2 = 39.04, p < 0.01). The frequency of collisions remains very significantly higher in the three distance categories closest to the towers, from 0 to 14.9 m (X2 = 43.64, p < 0.01). The highest frequency for very significant collisions of bats is that of insectivores (X2 = 222.10, p < 0.01). A very significant frequency of collisions was observed in 2015 (X2 = 68.75, p < 0.01). Key periods like fall and spring bird migration should be prioritized when planning collision monitoring plans. Standardized monitoring protocols and implementation of estimated mortality formulas that compensate for the search effectiveness of observers, the search area, and the removal of collisions are also important for not underestimating bird and bat collisions.