Factors influencing density of the Northern Mealy Amazon in three forest types of a modified rainforest landscape in Mesoamerica

Abstract

ABSTRACT. The high rate of conversion of tropical moist forest to secondary forest makes it imperative to evaluate forest metric relationships of species dependent on primary, old-growth forest. The threatened Northern Mealy Amazon (Amazona guatemalae) is the largest mainland parrot, and occurs in tropical moist forests of Mesoamerica that are increasingly being converted to secondary forest. However, the consequences of forest conversion for this recently taxonomically separated parrot species are poorly understood. We measured forest metrics of primary evergreen, riparian, and secondary tropical moist forest in Los Chimalapas, Mexico. We also used point counts to estimate density of Northern Mealy Amazons in each forest type during the nonbreeding (Sept 2013) and breeding (March 2014) seasons. We then examined how parrot density was influenced by forest structure and composition, and how parrots used forest types within tropical moist forest. Overall, parrot density was high in the breeding season, with few parrots present during the nonbreeding season. During the breeding season, primary forest had significantly greater density of 18.9 parrots/km² in evergreen forest and 35.9 parrots/km² in riparian forest, compared with only 3.4 parrots/km² in secondary forest. Secondary forest had significantly lower tree species richness, density, diameter, total height, and major branch ramification height, as well as distinct tree species composition compared with both types of primary forest. The number of parrots recorded at point counts was related to density of large, tall trees, characteristic of primary forest, and parrots used riparian forest more than expected by availability. Hence, the increased conversion of tropical moist forest to secondary forest is likely to lead to reduced densities of forest-dependent species such as the Northern Mealy Amazon. Furthermore, the species' requirement for primary tropical moist forest highlights the need to reevaluate conservation status of the Northern Mealy Amazon, and implement strategies to reduce forest conversion.Facteurs influant sur la densité de l'Amazone guatémaltèque dans trois types forestiers d'un paysage altéré en forêt pluviale de Méso-Amérique RÉSUMÉ. Le taux élevé de conversion des forêts tropicales humides en forêts secondaires rend impératif l'évaluation des relations entre les paramètres forestiers et les espèces dépendantes des vieilles forêts primaires. L'Amazone guatémaltèque (Amazona guatemalae), espèce menacée, est le plus gros perroquet continental; cette amazone s'observe dans les forêts tropicales humides mésoaméricaines, qui subissent de plus en plus de conversion en forêts secondaires. Cependant, les conséquences de la conversion forestière sur cette espèce, qu'on vient de séparer taxinomiquement, sont mal connues. Nous avons mesuré les paramètres dans des peuplements primaires de forêt tropicale humide d'arbres à feuillage persistant et riparienne, ainsi que dans des peuplements secondaires de forêt tropicale humide dans la région de Los Chimal...

Influence of Landscape Structure on Toucans and Parrots in the Fragmented Landscape of Los Tuxtlas, Mexico

“…Our results are consistent with other studies that demonstrated that forest cover—a proxy of habitat amount and the most used landscape composition variable—has stronger effects on the abundance or occurrence of bird species in tropical forests (Bonfim et al, 2021; Carrara et al, 2015; Cerezo et al, 2010; Morante-Filho et al, 2021). Results from this study also support other studies which have demonstrated that some parrot species are more abundant within preserved sites with highest forest cover (De Labra-Hernandez & Renton, 2017; Legault et al, 2011). An increasing number of individuals of both toucans and parrots with higher amount of forest is likely explained by the high resource availability for large-bodied cavity nesting birds, like toucans and parrots, in forest habitats (Cornelius et al, 2008; De Labra-Hernández & Renton, 2016; Zanette et al, 2000).…”