The thick-billed parrot, or cotorra serrano, is a colorful and gregarious species that flies in raucous flocks throughout the high elevations of the Sierra Madre Occidental ranges of Mexico. Historically, the thick-billed parrot’s range once extended as far north as the mountains of southeastern Arizona and possibly southwestern New Mexico.

Sadly, this bird has been extirpated in the U.S. since 1938 due to excessive unregulated shooting, and is now restricted to a handful of sites in Mexico. The parrot is classified as ‘Endangered’ by the IUCN, and its populations continue to decline. Only 1 % of the original old-growth forest that comprises key habitat supporting the parrots remains, and even these last forests are being reduced, degraded and fragmented by logging and from wildfires exacerbated by climate change.

The small size of the remaining parrot populations, combined with the low number of breeding pairs in the remaining forests in Mexico, have made thick-billed parrots particularly vulnerable to catastrophic events.

Thick-billed parrots are long-lived and highly social birds that migrate seasonally from their primary breeding (summering) grounds in the Mexican state of Chihuahua to wintering areas farther south, possibly traveling many hundreds of kilometers between these sites. Unfortunately, the exact locations of their winter habitats are largely unknown and the species is highly data-deficient.

Consequently, efforts to conserve and restore thick-billed parrot populations and the forests that support them will be stymied without better understanding of parrot migratory patterns, resource selection and habitat use. Recognizing the urgency of this conservation challenge, San Diego Zoo Global has partnered in a bi-national project with the Arizona Fish and Wildlife Department (AZDFW), Mexico’s National Commission of Natural Protected Areas (CONANP), and the Mexican conservation NGO Organización Vida Silvestre A.C. (OVIS) to conduct the first formal tracking study of thick-billed parrots in the wild.

We recently traveled to Chihuahua and the picturesque mountain forests of the Sierra Madre Occidental to deploy miniaturized tracking devices on an initial sample of 10 thick-billed parrots. Funding support for the project was generously provided by the San Diego Zoo Wildlife Conservancy.

We carefully attached these small and very lightweight transmitters to the birds using a backpack harness that does not interfere with the bird’s flight, behaviors or survival.

To ensure that the transmitter and backpack design was entirely benign, we first conducted a supervised captive study using a thick-billed parrot named “Sarge” who was transferred to the San Diego Zoo Safari Park from the Living Desert Zoo and Gardens and quarantined at our Harter Vet Hospital. This captive trial also enabled us to customize the best fit of the harness to the parrot’s form, and Sarge has since gone on to happily integrate with the rest of the parrot flock in our Zoo breeding program. Once we were confident with our attachment technique, we then met up with field biologists from OVIS to begin the capture and tagging process using wild birds.

The OVIS team has been busy setting up artificial nest boxes high up on pine trees throughout the thick-billed parrot’s summer habitat to encourage the birds to breed. With the chicks inside the nest boxes now fully grown and on the verge of fledging and leaving, the OVIS biologists were able to climb the trees, carefully secure the birds, and lower them to the ground where we could conduct our health checks and attach the transmitters.

We deployed transmitters on 4 fully grown chicks and 6 adults in the space of just one week. The transmitters are solar-powered and broadcast the bird’s location data to us remotely via a network of satellites, so once the birds are wearing the transmitters we can monitor their movements indirectly without disturbing them. The transmitters have already begun providing high-quality data on the spatial behaviors of the tagged parrots, and as the temperatures in the mountains have begun to drop, the transmitters are showing us how the birds are starting to move south to warmer latitudes as well as the migratory routes they are following.

In the coming months, we hope to build a detailed picture of thick-billed parrot spatial ecology and habitat use and use this new information to directly inform and enhance strategies to conserve this beautiful and increasingly endangered bird.