By Sara Westhead

BZS/Steinhoff Scholarship recipient Miguel Mejias, a Biology student at Memorial University in St. John’s, Newfoundland, has been undertaking some very interesting and exciting research on White-tailed Tropicbirds (Phaethon lepturus catesbyi), better known to most Bermudians as the “Longtail”. Central to his study is the use of small, light-based geolocators to track the movements of Longtails when they are not in Bermuda during the breeding season.

The study will be central to his MSc thesis, where he will be looking at answering three questions: (1) identifying the timing of migration and routes used by Longtails to and from Bermuda; (2) identifying key areas used by Longtails during the non-breeding season; and (3) describing the behavior (i.e., time spent flying, foraging and resting on the water) of Longtails during the non-breeding season.

“I became interested in the project primarily because I knew it was an aspect of Longtail ecology that we knew nothing about. Up until now, we had ‘hunches’ of where Bermuda’s Longtails migrate over the winter, but no definitive proof,” Mr. Mejias said. “Also, Jeremey Madeiros did a similar study with the Bermuda “Cahow” Petrel (Pterodroma cahow), so the opportunity to conduct similar research was too tempting to pass up. With this technology, I’ll be addressing the three primary questions of my MSc thesis.”

The study began in 2014 with the goal of capturing 30 adults while they were in their nests, and equipping each with a small (less than 1g in weight) geolocator on their leg. The start, however, was less than ideal and fraught with challenges. Firstly, the geolocators did not arrive until early July, which is when breeding season is almost finished, during which time the adults spend no more than five to ten minutes in their nests, because the chicks are large enough to regulate their own body temperature and only require infrequent meals. Secondly, Miguel had heard stories that previous attempts to tag Longtails had not been successful as the birds had been known to pull the tags off their feet. In spite of these challenges, the team were finally able to successful tag 30 late nesting adults by early August, though there was no guarantee that the tags would stay on, let alone whether the birds would survive and/or return to the same nest.

“I returned to Bermuda on April 10th and I’ve been tirelessly revisiting the nests of the birds tagged in 2014,” Miguel shared. “I am pleased to say that as of May 15th, I have successfully recovered 21 of the 30 tags I deployed last year – a 70% recovery rate in just a month! All of the tagged birds appeared to be in good health; their weights were taken upon recapture and will be statistically compared to their respective pre-tagging weights for any effects of wearing tags.”

“Just as exciting is that all 21 tags were fully functional and provided exciting tracks of the Tropicbirds movements and data on the amount of time each bird spent on the water versus flying – all very exciting results to report! And from what I can see, none of the tags we deployed last year have fallen off, meaning that the remaining 9 tags are from birds I have yet to encounter in 2015. These birds have either not been in the nest during my checks, have yet to return, or have died over the winter periods.”

BZS/Steinhoff Scholarship recipient Miguel Mejias has been
tracking longtails as a part of his MSc thesis. Photo supplied.

It is still too early to determine the full extent of the data being collected, however Miguel and his team are already uncovering some amazing data, particularly in terms of how far these birds actually travel during migration. The information is also helping scientists identify key foraging areas of seabirds during the winter months, allowing them to see where these areas may overlap with ‘danger zones’ and help to identify potential threats to the species.

“Conservation is based largely on a ‘value system’,” Miguel explained. “In other words, we as humans wish to protect the things we deem as precious. The reality is that Bermuda, as a country, will continue to persist, regardless if Longtails were to become extinct or not. However, on the other side of the argument – the side my mentors, colleagues and I firmly stand on – is that protecting the remnants of Bermuda’s native species is extremely important.”

“Since the arrival of man in the 1500s, the native flora and fauna suffered extinction, extirpation and severe reduction in population size. In respect to seabirds, the actions of man have reduced the once large number of breeding seabird species on the island to merely three: The Bermuda Cahow, Longtail, and Common Tern (Sterna hirundo), the latter, ironically, being the rarest of the three in Bermuda. Humans are solely responsible for the decimation of our island’s seabirds.

“Now that species like Longtails are no longer subjected to subsistence hunting, I personally feel that we, as Bermudians, are obligated to help undo the damage done to our biodiversity by our predecessors and hold on to the few things that make Bermuda unique.”