Tall trees and nest-boxes: a winning combination for Yellow-headed Parrots

December 13th, 2021 | by David Waugh
Tall trees and nest-boxes: a winning combination for Yellow-headed Parrots
Conservation projects

Oh wow, just look at that! The exclamation of dismay emanated from the researchers as they huddled over the gruesome camera-trap image. It showed a Belizean Yellow-headed Parrot chick (Amazona oratrix belizensis) being dragged out of its nest-cavity by a Tayra (Eira barbara), a robust, agile and ferocious predator, cousin to stoats and martens, and widely distributed in South and Central America. In any event the camera-trap solved the disappearance of the chick, but Tayras are natural predators, and the least of the Yellow-headed Parrot’s problems. 

This is an endangered species found in Mexico, Belize, Guatemala, and Honduras, which has undergone a dramatic population decline throughout its geographical distribution, with an estimated reduction of up to 79% from its original size. The densities of this species in Belize may be the highest found throughout its distribution, but although it used to be widespread in Belize’s coastal region, habitat damage and illegal pet trade have now largely confined the species to pine-oak forests of the coastal plains in central and north-west areas.

Adult Yellow-headed Parrot in coastal savannah shrub.

Annual illegal fires are a serious threat to the pine savannas in the southern coastal area which have reduced the presence of natural cavities in dead pines, although large roosts apparently still persist in that part of the country. By contrast, some areas in northern Belize have extensive occurrence of possibly suitable natural nest cavities in Caribbean pines resulting from hurricane-related disturbance.

The field team climbs a tall pine to check one the nests.

To help combat the threats and stimulate the recovery of the Yellow-headed Parrot, a research and conservation project is underway, supported with US$116,730 since it started in 2016 by the Loro Parque Fundación. Expert field biologist Charles Britt initiated the work with his Scarlet Six Biomonitoring Team, in a strong collaborative effort with the Belize Bird Conservancy, Belize Forest Department, Toledo Institute for Development and Environment and the Environmental Research Institute.

Camera-trap image of a pair of Yellow-headed Parrots at their nest entrance.

The project involves the monitoring of the Yellow-headed Parrot population by means of regular census, the finding, monitoring and protection of nests in the February to June breeding season, the evaluation of nesting success, vigilance against nest poaching and burning of habitat, and the return to the wild of individuals under human care.

The clutch size of the Yellow-headed Parrot is frequently three.

An additional element of the project has been to install nest-boxes in suitable habitat. The first artificial nests were quickly occupied by pairs of Yellow-headed Parrots, suggesting a lack of suitable natural cavities. This stimulated a more concerted effort to provide nest-boxes, and the success of these and natural nests has recently been reported by research biologist Fabio Tarazona-Tubens*. Fabio’s work was essentially to identify natural and human causes of nest failure, and to use the information to inform conservation actions to increase recruitment of young parrots into the existing population.

A chick under-going a routine check-up.

He monitored 124 nests (97.6% in Caribbean pines) of Yellow-headed Parrots between six study sites during the 2017 and 2018 nesting seasons, 78 in natural cavities in live trees, 38 in nest-boxes and eight in dead trees. From the total of nests, the average clutch size was 2.57 and average number of fledglings per successful nest was 1.87. The main cause of nest failure was nest depredation (50%), followed by nest abandonment (27%) and nest poaching (20%), The few remaining nests failed either due to structural failure of the cavity or flooding. In addition to the Tayra, other predators identified by cameras at the nest included an unidentified rodent, three bird species, an iguana and a snake. One of the bird species was the Bat Falcon (Falco rufigularis), which could also count as a nest competitor, and perhaps precipitate nest desertion.

The Bat Falcon (Falco rufigularis) is one of the competitors for nest-boxes, this example being recessed into the trunk of the pine tree.

Although most observed cases of abandonment happened during the incubation stage, two nests were deserted during the early nestling stage. Thus, predation and abandonment events were documented earlier in the nesting season, while poaching events occurred later (60.7 days average age of chicks for poached nests) during the average 88-day nesting period. Even though time of the nesting season affected nest poaching, it was also influenced by human-related features such as distance to nearest settlement and distance to road.  Fabio investigated the use by Amazon parrots of two forms of vertical nest-box, one of typical installation standing proud from the tree trunk, the other inserted into a recess cut into the trunk. He also examined the selection requirements of the parrots in relation to vegetation cover around the nest site and characteristics of the nest tree.

Caught in the act. Camera-trap image of a Tayra predating a Yellow-headed Parrot chick.

For this part of his research he had 60 nest-boxes, of which 60% were used by four species of Amazon parrots, the White-fronted (Amazona albifrons) and Yellow-headed Parrots accounting for most use. Increasing height of the nest tree had a strong positive effect on nest selection, and areas with less vegetation cover and greater visibility from the nest were also preferred, but without such a strong effect on selection. Yellow-headed Parrots selected nest-boxes in taller trees, closer to previously successful nests, and it is clear that these trees should be protected from poachers and fire.

This work highlights the success of nest-boxes and their potential broader use as a conservation tool, and the results can be used to establish ways to reduce depredation rates and to anticipate which nests are most vulnerable to poaching based on their location and stage of nest development.

Author: David Waugh, Correspondent, Loro Parque Fundación

Photos credits: Title, 1,2,3,5,6,7 + TITLE – Belize Bird Conservancy; 4 – Charles Britt/BBC

* Fabio L. Tarazona-Tubens (2020) Nest survival of Yellow-headed Parrots and selection of nest boxes by Amazon parrots in Belize. Master of Science thesis, New Mexico State University Las Cruces, New Mexico, USA


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