Summary
Highlights
The episode begins by questioning how animals navigate vast distances without getting lost, prompted by a listener's query. It sets the stage for a two-part special, with this episode focusing on where animals go and why they migrate.
David Barrie, author of 'Incredible Journeys', discusses various migrating animals, from the Arctic tern's 100,000 km annual trip to the humpback whale and the bogong moth. He explains that migration was a controversial idea until the 19th century, with bizarre theories like swallows sleeping in ponds. The discovery of a stork in Germany with an African arrow provided early hard evidence of migration.
Professor Tim Guilford of Oxford University explains that migration is not universal, but in seasonal regions, it's a trade-off between the energetic costs and risks of travel versus the rewards of exploiting abundant resources in different locations, essentially seeking an 'endless summer'. He highlights the extreme adaptations, such as bar-tailed godwits digesting internal organs to become lighter for long flights.
The episode describes the classic bird ringing (banding) technique, which started in the late 19th century. Thousands of volunteers attach small metal rings with unique IDs to birds, and the recovery of these rings helps scientists map migratory routes and timings over decades. The team travels to Belize to witness this process firsthand.
In Cockscomb Basin Wildlife Sanctuary, Abidas Ash and her team demonstrate bird banding. They use mist nets to catch birds, extract them carefully, and collect data on their age, sex, and condition. The goal is to monitor bird populations and understand their migratory patterns. They successfully catch and band a rufous-tailed hummingbird.
The team finds a Greycap bird that was banded three or four years prior, illustrating the long-term value of banding data. This individual had likely made multiple trips to Belize, highlighting the importance of the sanctuary as a wintering ground due to its abundant food resources. Data from banding stations like Cockscomb are crucial for conservation efforts, informing organisations like the MoSI programme.
Tim Guilford returns to discuss miniaturised technology revolutionising bird migration research. GPS devices track foraging journeys, while geolocators (tiny light-registering devices) are fitted on leg rings. By analysing dawn, dusk, and day length, researchers can reconstruct a bird's entire migratory path, revealing previously unknown hotspots like a marine protected area in the North Atlantic.
Professor Kristen Ruegg of Colorado State University explains how genetic analysis, even from a single feather, can identify a bird's breeding population of origin. This 'ancestry website for birds' helps determine genetically distinct populations crucial for targeted conservation, especially for endangered migratory species. It also helps in studying genes linked to migratory timing, which is vital for understanding adaptation to climate change.
The episode concludes by teasing the next instalment, which will focus on how animals navigate. It highlights the mystery of how creatures like sea turtles travel between continents and return to the exact same beach. The team will join researchers tracking sea turtles off the coast of Florida on the RV Luminia to understand their movements and the conservation challenges they face in the marine environment.