A black-throated blue warbler

Throughout the years, the Department of Natural and Environmental Resources (DNER) has been monitoring native and migratory birds in Puerto Rico.

Between 2008 and 2012, surveillance was established in the state forests of Boquerón and Guánica, capturing birds in mist nets during different seasons of the year. However, the complexity of nature observation and preservation efforts requires more than just the desire to do so: it must be supported by resources and the best scientific methods and technological advances.

By virtue of the research, “The short-term establishment of a monitoring station for neotropical warblers (resident and migratory) in ecotones between the dry forest and the wetland in two tropical wildlife protected areas (T-8),” funded by DNER and the U.S. Fish and Wildlife Service (USFWS), several species documented in the 2005 Puerto Rico’s Comprehensive Wildlife Conservation Strategy were studied.

“The idea was that the new information would be useful to update the population status of these birds in the ‘Puerto Rico’s State Wildlife Action of 2015,’” explained Katsí Ramos Álvarez, DNER biologist and bird specialist, and co-author of the neotropical warblers study.

Since then, DNER scientists assigned to the study have also been collaborating in monitoring these birds using mist nets every winter in the Guánica State Forest, a project led by John Faaborg of the University of Missouri and Wayne Arendt of the U.S. Forest Service (USFS). Through this project, information has been collected for bird surveillance for more than 47 years, along with academics, volunteers and USFS officials, among others.

Ricardo López Ortiz, director of the DNER’s Fisheries Research Laboratory, highlighted that “the last time this collaboration was achieved was in the winter of 2019 because the 2020 sampling was suspended due to the precaution of the earthquake that shook the area of Guánica. This last sampling was achieved despite the federal government shutdown period and the lack of a federally approved budget, which greatly limited the response time to get volunteers.”

During this period there was the collaboration of organizations from other countries, and also the essential collaboration of the Ponce School of Medicine, which opened a new dimension to scientific research. The recent effort was coordinated by Judith Toms of the Canadian Wildlife Service, Ramos Álvarez, and López.

That occasion stimulated additional collaboration, with Vanessa Rivera Amill and microbiologist Pablo López Colón, both from the Research Resource Center of the Ponce School of Medicine, and who evaluated a novel way to more accurately determine the sex of captured birds, revealed López.

Key Scientific Research

DNER Secretary Rafael Marchago highlighted the importance of this initiative. “Being able to accurately determine the sex, age, provenance and habits of the species is important to be able to monitor that the populations remain healthy. For example, a shortage of fertile females can result in a significant population reduction. However, determining sex in species without sexual dimorphism can be very difficult,” he stated.

The term sexual dimorphism implies different forms for each sex, referring to variations in external characteristics, such as shape, coloration, or size between males and females of the same species, the DNER explained.

According to Rivera Amill, the novelty of the work is that the determination of the sex of the birds sampled in Puerto Rico is carried out by examining the DNA of much less than a drop of blood extracted. This blood is obtained from the calamus of carefully chosen feathers so that they do not affect the survival of the specimen. The procedure is minimally invasive because birds shed their feathers regularly.

The genetic sequences are then submitted to GenBank, a database of genetic sequences from the National Health Institute. According to López, by submitting the genetic sequences, researchers from anywhere in the world can use them for their studies. The scientists involved in this research are in the process of writing a scientific publication with the results.

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