Monitoring invasive mammalian predator populations sharing habitat with the Critically Endangered Puerto Rican parrot Amazona vittata

Abstract

Critically Endangered Puerto Rican parrots Amazona vittata are one of the rarest birds in the world. Several exotic mammal species capable of preying on Puerto Rican parrots cohabit the Caribbean National Forest with the only wild population of these parrots. We used tracking plates, monitoring blocks and trapping to index black rats, small Indian mongooses and feral cats in parrot habitat and in public-use areas in the same habitat type. We had high trap success for black rats at all sites (42% of all sites combined), among the highest reported in the world. Rat response to monitoring (nontoxic bait) blocks was universally high, regardless of ground or tree placement. Mongooses were present at all sites, with a greater proportion of plates tracked within the forest than at public-use sites. Cats were present at all forest sites and one of the public-use sites. Presence of the three species did not appear to be linked to human disturbance. Because only 30–40 Puerto Rican parrots survive in the wild, with as few as three pairs nesting in 2002, we concluded that the abundance and pervasiveness of exotic mammalian predators poses a greater threat to the parrots than has been generally acknowledged. This is evidenced by mammalian predation during recent parrot breeding seasons, including six fledglings taken by mongooses and one nest failure from rats during 2000–2003.

Predicting species interactions from edge responses: mongoose predation on hawksbill sea turtle nests in fragmented beach habitat

“…R. Soc. B (2008) (c) Artificial nests and predator tracking as new tools for sea turtle conservation Data on predation can be difficult and labour intensive to obtain, especially where the species of interest are rare (Engeman et al 2006). We show that two relatively simple and inexpensive techniques, artificial nest experiments and passive tracking of predator abundance, applied over a three-week period, successfully predicted multi-annual spatial patterns of nest predation for hawksbills.…”

The West Indies as a laboratory of biogeography and evolution

“…Removing predators such as mongooses from large islands in the West Indies probably will not be possible, despite the success of predator control programmes on smaller islands in other parts of the world (Bloomer & Bester 1991;Robertson et al 1994;Courchamp et al 2003). Direct intervention by providing nesting sites, predator control (Engeman et al 2006) and captive propagation (Russello & Amato 2004) is being attempted for several of the parrot populations of the West Indies with mixed success. Where populations of a species occur on several islands, introductions from one island to bolster a failing population on another island is possible, but it is important to determine the genetic distinctiveness of individual island populations before mixing them (e.g.…”

Feral Cats

“…Although extinctions attributed directly to mongooses are likely few (Henderson 1992), there are several cases in which population declines have been exacerbated by mongoose introduction. In Puerto Rico, the introduced mongoose has been implicated in the decline of the Puerto Rican parrot (Amazonia vittata; Engeman et al 2006) and Puerto Rican nightjar (Antrostomus noctitherus; Vilella and Zwank 1993). Mongooses are also known to prey upon the Puerto Rican giant anole (Anolis cuvieri; Schwartz and Henderson 1991), coqui frogs (Eleutherodactylus spp.…”

“…In an effort to protect populations of endangered Puerto Rican parrots as well as human health and safety, limited mongoose control is performed on Puerto Rico (Engeman et al 2006;Quinn et al 2006). Rather than large-scale eradication efforts, local control of mongooses has been conducted much more frequently, with live box traps the most common method employed (Barun et al 2011).…”