Tracking the Tropicbirds of Sal
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How much do you know about the bird in our logo? Though its elegant white tail streamers and red beak make for striking features that are easy to identify, unless you are climbing high along the coastlines, the Red-billed Tropicbird (Phaethon aethereus) may be hard to find!
Referred throughout the islands of Cabo Verde by its Portuguese name, Rabo-de-junco, this bird is a loosely colonial species that nests in the rocky cliffs where there is easy access to the open sea. Their diet consists primarily of small fish and squid caught by plunge diving. This species is also highly pelagic, spending the majority of their adult lives at sea, only coming to land to breed and normally laying only one egg per year.
It’s in part their breeding patterns that make Red-billed Tropicbirds particularly sensitive to environmental changes. This species often return to the same locations to breed, and remain as a pair throughout their lifetime making them increasingly vulnerable to threats such as predation from introduced species such as cats, rats, and other mammals, as well as human-induced threats such as ocean pollution and poaching of the adult and chicks.
Although they are not listed as threatened by the International Union for Conservation of Nature (IUCN), their populations are in decrease globally. In Cabo Verde there have been registers of predation of adults, chicks and eggs by feral cats and stray dogs. Lately, we found what are clear evidence of human harvesting for consumption, a known threat that we never registered before in Sal.
In 2017, as part of a partnership with the University of Barcelona, Project Biodiversity launched a new programme monitoring Sal’s seabird population in an effort to learn more about the biology, migration and breeding patterns of these iconic birds as part of an effort to help curb an increasing decline in populations. This programme is included within a wider project lead by Birdlife International, Alcyon Project, that aims to protect seabird and marine IBAs (Important Bird Areas) in West Africa.
Our team’s focus is largely on field work, which includes ringing to determine population size, as well as deploying geotags and GPS devices to help study migratory patterns. At the same time, they are analyzing blood samples and uropygial oil to assess the source of food and the incidence of organic and inorganic pollutants. By gathering all of this information, our team is slowly piecing together critical details needed to assess the health of the population in Sal and throughout Cabo Verde.
Over the last two years, the data collection from our biologists has yielded a number of important discoveries, in particular, that the island of Sal is likely one of the most important breeding site for the Tropicbird population in West Africa. Most recently, our team collaborated with the University of Barcelona to publish our initial findings as part of a larger assessment on how migratory data could help inform large-scale management solutions for pelagic species.
On a local scale, this data is providing key insights into the more immediate and specific threats to Sal’s Tropicbird population, and is an essential part of helping our team as we look ahead to design high impact, locally-focused conservation solutions for this iconic species.
In parallel to our work in the field, our team is committed to sharing our insights with others within the field of seabird conservation. On April 9-11th we’ll present our most recent findings at the 5th Annual Seabird Twitter Conference hosted by the World Seabird Union. Log on to Twitter, and follow the hashtag #WSTC5 for the Seabird Twitter Conference and #ConsSesh2 to see our presentation!