Predation of nesting Thick-billed Parrots Rhychopsitta pachyrhyncha by bobcats in northwestern Mexico

Abstract

Summary We report on what appear to be increasing predation events on nesting Thick-billed Parrots Rhychopsitta pachyrhyncha. Thick-billed Parrots are classified as ‘Endangered’ and their seasonal breeding range is restricted to increasingly fragmented and degraded high elevation mixed conifer forest habitat within the Sierra Madre Occidental region of north-western Mexico. Predation of established breeding pairs has recently contributed to the ongoing decline of Thick-billed Parrot populations by removing mature birds with high reproductive value, which has associated consequences for future recruitment. We observed increasing predation events on nesting Thick-billed Parrots by bobcats Lynx rufus accompanied by kittens throughout the 2018–2019 breeding seasons, and we speculate that recent reductions in bobcat habitat have pushed them into new ranges where they are supplementing their diet with nontraditional prey items.

Spatial behaviors and seasonal habitat use of the increasingly endangered thick-billed parrot (Rhynchopsitta pachyrhyncha)

“…Availability of nesting cavities in mature trees and snags in the Sierra Madre Occidental has dramatically decreased in recent decades due to destructive clear-cutting and high-intensity timbering of remnant old-growth primary forests. Installation of artificial nest boxes at parrot breeding sites has helped improve nesting success and reduced predation risk (Sheppard et al 2021), although this solution is labor and resource intensive and difficult to sufficiently scale. As of 2023, only 19.6 % of the total thick-billed parrot nesting home range area, 8.5 % of the total overwintering home range area, and 6.4 % of the total area of migratory stopover sites that we calculated are covered by formal regulatory protections, such as a reserve or natural protected area designation (Appendix 4.…”

“…Surveys of thick-billed parrot populations conducted over the past 25 years within their remaining breeding sites show a decline of 20 – 30 %. The most recent surveys indicate there may be fewer than 2000 individual birds extant (Sheppard et al 2021), although this number is dubitable due to the irregularity of survey intensity. This precipitous drop in thick-billed parrot populations has been linked to the decline in suitable nesting resources (Monterrubio et al 2002, Monterrubio-Rico and Enkerlin-Hoeflich 2004), as well as a trend observed in recent years of increasing predation events on nesting thick-billed parrots and their chicks (Sheppard et al 2021).…”

“…The most recent surveys indicate there may be fewer than 2000 individual birds extant (Sheppard et al 2021), although this number is questionable due to the irregularity of survey intensity. This precipitous drop in thick-billed parrot populations has been linked to the decline in suitable nesting resources (Monterrubio-Rico and Enkerlin-Hoeflich 2004), as well as a trend observed in recent years of increasing predation events on nesting thick-billed parrots and their chicks (Sheppard et al 2021). Less than 20 % of the thick-billed parrot population will typically breed annually, so the species can persist and recover only if sufficient nesting resources are available (Monterrubio et al 2002).…”

“…Surveys of thick-billed parrot populations conducted over the past 25 years within their remaining breeding sites show a decline of 20 – 30 %. The most recent surveys indicate there may be fewer than 2000 individual birds extant (Sheppard et al 2021), although this number is questionable due to the irregularity of survey intensity.…”

Genetic Diversity and Population Structure of Two Endangered Neotropical Parrots Inform In Situ and Ex Situ Conservation Strategies

“…Threats faced by the thick-billed parrot include habitat loss due to logging operations throughout its range as well as historical pet trade capture and shooting [37][38][39]. A recent study discovered evidence of increased rates of predation by bobcats and recommended increased antipredation methods at nesting sites [40]. Studies have suggested that reduction of logging and favorable ecological conditions in the thick-billed parrot habitat range are key to its recovery [41].…”