For seabirds, producing their next generation requires access to shoals of fish, both for energy to develop eggs and for delivery to hungry chicks that are left onshore while parents fly out to forage.
For that reason, where a population elects to nest can shift depending on where the fish are. This year, part of the Western Australian population of fairy terns chose an elevated beachfront at McKenna Point, within Bunbury’s port. Biologists from the Department of Biodiversity, Conservation and Attractions (DBCA) worked with the Port to monitor the breeding and manage human access to minimise disturbance. Thanks to these efforts, this weekend was finally time to band the chicks that were large enough to scurry away on the beach, but not yet able to fly. Rounding up these “runners” takes a team of volunteers with head torches and fast hands.
Members of the CCWA's Western Australian Fairy Tern Network joined with members of the Bunbury branch of BirdLife WA and staff members from DBCA about an hour before sunset to “scope out the situation”, literally—using spotting telescopes and binoculars to see where the nest scrapes began and ended along the beach, to estimate how many pairs had chicks, and where scrapes (shallow depressions in the sandy substrate that are all that constitute a tern’s “nest”) may still contain unhatched eggs. As the sun set, the volunteers organised into two teams and dispersed to opposite ends of the colony. Moving slowly in a line, using a headlamp beam directed just in front of our feet, we scanned the sand, aiming to scoop up the chicks before they realised that they were being approached. At the same time, we had to watch our steps — tern eggs are patterned remarkably like a coarse beach sand mixed with shell debris and dark bits of vegetation.
Chicks hunkered down on mats of tossed-up sea wrack, scuttled under plants and into the dune grass, or hoped that the artificial shelters placed by DBCA made them invisible; they didn’t. Wrangled runners were collected in a carrying container and we moved out of the wind to mark this year’s birds cohort of young. Each chick that had erupted pin feathers (that will eventually enable it to fly, as opposed to the down which functions to keep them warm once out of the egg) was given an individually numbers ABBBS leg band. The more mature chicks were also give plastic colour bands that will identify them as having hatched on this beach. Different colours are applied at each nesting colony along the WA coast, enabling scientists and citizen scientists alike to identify where these youngsters go once they fledge. While the team applied bands and colour bands to the chicks, the lead scientist captured a few adults which also received identifying bands.
As soon as all the chicks were marked, they were returned to the centre of the colony. A bit confused, but ever hungry, the chicks resumed vocalising, bringing parents in on the wing. Adults can recognise their own chicks’ voices, and releasing the runners in a centralised location facilitates the pairing up of parents and young. Because these young were already out of their nesting scrapes, the parents know that they could be anywhere along the beach, and so finding them in a new location is standard fare for a foraging adult returning with food for its young.
Thanks to cooperation from land and wildlife agents, and citizen scientist volunteers, the CCWA Western Australian Fairy Tern Network is learning more each season about the dynamics of Australia’s tern through reports by volunteers throughout WA. Banding enables anyone to track dispersal through structured and casual resightings of the highly visible colour bands. We can monitor recruitment as breeders and longevity (individual lifespan) when banded individuals are recaptured later in life. Citizen scientists in the Network add their photographic “recaptures”— high-resolution pictures that sometimes even provide individual band numbers. Modern technology has come so far since the age of digital photography began that any science-minded person contributing their bird sighting “records” builds on the available knowledge; we learn more, faster, through volunteers.