Invasive House (Rattus Rattus) and Brown Rats (Rattus Norvegicus) Threaten the Viability of Red-Billed Tropicbird (Phaethon Aethereus) in Abrolhos National Park, Brazil

Abstract

Destruction of nests and predation by introduced species are among the main factors responsible for seabird declines.The red-billed tropicbird (Phaethon aethereus) is a tropical, colonially nesting seabird whose distribution in Brazil is restricted to a small, isolated breeding colony located within Abrolhos National Park. This represents the southernmost population of the species in the western Atlantic, and is among the most southerly in its global distribution. Despite its isolation, the population on Abrolhos is threatened by egg predation by two invasive rat species: the house rat (Rattus rattus) and brown rat (Rattus norvegicus). In this study we conduct a population viability analysis of P. aethereus in Abrolhos to estimate the potential long term impacts of the rats. Our results indicate that egg and chick predation by rats has the potential to quickly drive the Abrolhos tropicbird population into serious decline. Reducing this threat may require the urgent implementation of a rat control program.Keywords: seabird, conservation, eradication, Rattus, population viability.Resumo O Rabo-de-palha-de-bico-vermelho (Phaethon aethereus) é uma ave marinha tropical e colonial. No Brasil, essa espécie apresenta distribuição restrita, com uma pequena e isolada colônia nidificando dentro do Parque Nacional Marinho dos Abrolhos. Essa população está localizada no limite sul da distribuição da espécie no Oceano Atlântico ocidental, e entre as populações mais ao sul de sua distribuição global. Apesar de seu isolamento, a população de Abrolhos está ameaçada pela predação de ovos e filhotes por duas espécies invasoras de rato: rato doméstico (Rattus rattus) e rato marrom (Rattus norvegicus). Neste estudo realizamos uma análise de viabilidade populacional de P. aethereus em Abrolhos para estimar os potenciais impactos de longo prazo causados por esses ratos. Nossos resultados mostram que a população foi considerada viável sob condições ambientais naturais. No entanto, a predação por ratos foi identificada como uma potencial ameaça capaz de rapidamente levar a população dessa ave a um acentuado declínio. Para que essa ameaça possa efetivamente ser contornada defendemos que a implementação de um programa de gestão direcionado para controlar a população de ratos em Abrolhos deve urgentemente ser colocada em prática.Palavras chaves: aves marinhas, conservação, erradicação, Rattus, viabilidade populacional.

Combining monitoring data from multiple sites to assess population status and trends of White-tailed Tropicbirds (Phaethon lepturus) in the Seychelles

“…This could be confirmed by setting camera traps at nest sites to observe nest failure events. The low breeding success recorded at Aldabra conforms to results from other studies where invasive predators are present and supports the claim that, in the case of White-tailed Tropicbirds, predation by invasive species, primarily rats (Russel and le , Sarmento et al 2014, as well as native species (Phillips 1987, Schaffner 1991, is the main cause of nest failure in the Seychelles. We therefore conclude that for stable populations, it is likely that the differences observed in breeding success amongst the Seychelles islands are primarily due to the composition and abundance of local predators.…”

Breeding of White-tailed Tropicbirds (Phaethon lepturus) in the western South Atlantic

“…Conner, 1975;Stauffer and Best, 1982). For WTTBs, breeding success has been observed to be affected by nest abandonment, intraspecific combats and predation by rats (Rattus rattus (Linnaeus, 1758) (Garnett and Crowley, 2000;Sarmento et al, 2014) and crabs (Gecarcinus spp. and Ocypode spp.)…”

“…Breeding success in colonial seabirds is particularly sensitive to fluctuations in food availability (Weimerskirch, 2001) and predation intensity (Whittam and Leonard, 2000;Nordström et al, 2004). In the case of Tropicbirds, predation by exotic species (mainly rats - Gaston and Jones, 1998;Sarmento et al, 2014) and native species (mainly large crabs -Phillips, 1987;Schaffner, 1991) is the main cause of mortality during breeding.…”

The Sex Attractant Pheromone of Male Brown Rats: Identification and Field Experiment

“…Brown rats (Rattus norvegicus)a re significant global pests. [1,2] They inflict harm by vectoring disease-causing pathogens, [3][4][5] soiling food, [6] spreading allergens, [7,8] diminishing yields of agricultural crops, [3,9] endangering island seabird colonies, [10] and as an invasive species harming indigenous fauna. [11,12] These many adverse effects caused by brown rats in urban centers [13] and in agricultural or ecosystem settings [14] have prompted ongoing efforts to trap or poison rats,i nt urn exerting selective pressure on rats to evolve counter-adaptations.N eophobia (the fear of new objects) is one such well documented counter-adaptation that helps rats avoid being trapped.…”