Colisão de aves marinhas migratórias em linha de energia no Nordeste brasileiro: avaliação espaço-temporal e descrição da histologia gonadal em áreas não reprodutivas com fins de conservação

Abstract

Among the human impacts suffered by birds, the collisions of these animals in linear structures, especially in power lines, are increasingly frequent and alarming. Studies on this topic, however, are still recent and scarce, especially in South America and Brazil. Migratory birds are animals that usually stand out in this type of impact, among which there are the marine species Sterna dougallii (ROST) and Sterna hirundo (COTE) that migrate to the South American coast during the boreal winter and can be found on the coast of Rio Grande do Norte (RN). Representatives of these two species began to be found by the beach monitoring teams of the Costa Branca Cetacean Project (PCCB-UERN), near a power distribution line, with signs of collision, on a beach on the coast of RN between the years 2010 and 2020. Tissue samples from animals that did not survive were stored in the PCCB-UERN biological sample bank. Because they are birds with a well-defined reproductive seasonality, their gonads undergo periodic changes, but little is known about their histological reproductive biology, as well as about the gonad stage of animals that are impacted by the distribution line in northeastern Brazil. In view of this series, the present research sought to characterize the events of bird collisions on a power line in the municipality of Galinhos/RN, in the face of changes in the environment associated with the construction of a wind farm, as well as to describe the morphology of the gonads and the gonadal stage of individuals involved in the problem. Collision data (place, date, animal biometrics) were collected between 2010 and 2020 daily and uninterrupted by monitoring the beach strip where the distribution line is. The birds found had their coordinates recorded and if they were alive they were sent to the PCCB-UERN Marine Fauna Rehabilitation Center. From the gonads of 62 birds that died, which were fixed in 10% formalin and submitted to laboratory routine for the preparation of histological slides, the reproductive biology was analyzed including gonadal histological description, gonadal stage, and sex ratio. Histological analyzes of the gonads revealed a pattern corresponding to that of other bird species. The ovaries presented the cortex region with follicles in different stages of maturation and also a well-pronounced medullary region; the testes showed seminiferous tubules with narrowed lumens and seminiferous epithelium without sperm production, as well as a well-developed interstitial tissue. As for the records of collisions, this research indicated that there was a significant increase in the frequency of collisions of birds with the power distribution line, coinciding with the installation of a wind farm on a neighboring beach, and which continued even after the installation of markers on part of the line wires. Research shows that wind farms can cause displacement in bird flight paths, which may indicate a possible influence of the park in the increase of collisions. In short, this research points out bird collision events on power lines never before recorded in RN due to lack of monitoring, indicates the possible influence of a wind farm in this process, and elucidates histological aspects of the reproductive biology of the impacted bird species.