Rounding up Rábida's hawks

By Francesca Cunninghame

The aerial broadcast of brodifacoum to eradicate rats from Rábida and several small Galápagos Islands took place in January. This was a Galápagos National Park project with Island Conservation, Bell Laboratories, Charles Darwin Foundation, University of Minnesota Raptor Center and Durrell. Durrell provided staff (that is me, field manager of the Mangrove Finch Project) for Galápagos hawk mitigation. A risk assessment showed these endemic hawks risked suffering from secondary poisoning and to prevent this all the hawks holding territories where bait was to be spread needed to be brought into captivity for at least six weeks. Holding aviaries were built by Park personnel at a secluded spot on Santiago Island.

At the beginning of January we set off to visit all of the islands that were to be targeted. Previous surveys had shown 19 hawks spread over three islands and we spent time with these birds, training them to eat from beside us, to facilitate their capture. Luckily for us, Galápagos hawks are incredibly tame and not particularly difficult to catch. From 4-8 January, we caught a total of 20 birds as a juvenile was captured too and these went by Park speedboat to the aviaries on Santiago. Galápagos hawks are polyandrous and females often hold territories and breed with several males. The 20 birds included only three, adult, females; the juvenile was also a male.

Julia Ponder (in the photo above), from The Raptor Center, was on hand to offer expertise in the hawks’ care and I joined Julia at the hawk camp for 10 days to help her look after the birds. All birds arrived in good condition, though a bit stressed, and were released into the aviaries. Birds from the same territories were held together; resulting in seven aviaries, and took a few days to settle but overall they adjusted well. The first days were full, as all birds were measured and blood samples taken. However, things quietened down as the daily routine became cleaning aviaries in the morning and feeding hawks in the afternoon. The birds’ diet consisted of three day-old chicks three times a week, goat meat three times a week, and dead rats on Sundays. A generator and freezer meant that we could maintain food supplies frozen and all the birds took to the food and maintained capture weights - the main problem was stopping them getting too heavy and we reduced the amount of food. Rats were their favourite! After two weeks the birds were settled and Julia and I left (Julia to return home and myself for Isabela to monitor mangrove finch breeding). Lori, a colleague of Julia’s, took over the shift with a Park ranger.

In February I returned to the hawk campsite to look after the birds until we released them. The temperature had risen, the sea had warmed up (28 degrees), it had started raining and the hawks were ready to be released. Monitoring showed that all the baits had broken down and very few dead rats were evident; those found were severely decomposed. In addition to the 20 captive hawks a group of 2-4 juveniles had started hanging around the campsite, one being a nearly permanent companion on a branch above the cooking stove. We were not feeding these birds but they knew we had a freezer of meat and they made thawing and cutting up food a challenge. On occasions they were even caught stealing onions and eating them - only in Galápagos could one find an onion eating raptor!

The captive birds did well, there were no health concerns and all were a good weight. All adopted individual characteristics; some were nervous and untrusting, whilst some were so tame they took food out of your hand before it was placed on a perch. All the hawks were fitted with radio transmitters, sitting between the wings like a backpack, to determine what happens to them after release.

It’s been a great opportunity to work with the hawks; they really are a special species and, while I’ll miss seeing them each day, I was glad when the time to release was approaching. They are birds that should be flying over the open lava fields, not sitting on perches in small aviaries. For the month following release, the Park will monitor the birds and leave meat for them while they adjust to life back in the wild.