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We report first-year survival for 34 captive-reared Puerto Rican Parrots (Amazona vittata) released in the Caribbean National Forest, Puerto Rico between 2000 and 2002. The purpose of the releases were to increase population size and the potential number of breeding individuals of the sole extant wild population, and to refine release protocols for eventual reintroduction of a second wild population elsewhere on the island. After extensive prerelease training, we released 10 parrots in 2000, 16 parrots in 2001, and eight parrots in 2002 ranging in age from 1–4 years old. All birds were equipped with radio-transmitters to monitor survival. The overall first-year survival estimate for the 34 parrots was 41% (CI = 22%–61%). Only one parrot died within the first week postrelease, with most (94%) surviving for at least eight weeks after release. Most (54%) documented mortalities were due to raptor predation, which claimed 21% of all released parrots. A captive-reared bird (male, age one), released in 2001, paired with a wild female and fledged two young in 2004. We also calculated survival based on 0% and 50% of observed predation losses and found hypothetical survival rates of 72% and 54%, respectively. Rigorous prerelease training and acclimation was believed to have improved initial postrelease parrot survival, and releasing mixed age-class groups suggests the potential for shortening the time to recruitment. Supervivencia de Individuos de Amazona vittata Criados en Cautiverio y Liberados en el Bosque Nacional del Caribe Resumen. Determinamos la supervivencia de 34 individuos de cotorras Amazona vittata criados en cautiverio y liberados en el Bosque Nacional del Caribe, Puerto Rico entre el 2000 y el 2002. El propósito de las liberaciones era aumentar el tamaño de la población y el número potencial de individuos reproductores en la única población silvestre remanente, y refinar los protocolos de liberación para eventualmente establecer una segunda población silvestre en la isla. Después de un adiestramiento extensivo, liberamos 10 cotorras en el 2000, 16 cotorras en el 2001, y ocho cotorras en el 2002 fluctuando en edades entre uno y cuatro años. Cada individuo se liberó con un radio transmisor para determinar su supervivencia. La tasa general de supervivencia para 34 cotorras después de un año fue de 41% (IC = 22–61%). Sólo una cotorra murió durante la primera semana post-liberación, con la mayoría (94%) sobreviviendo por lo menos ocho semanas después de liberadas. La mayoría (54%) de la mortandad se debió a la depredación por aves rapaces, la que reclamó 21% de todas las cotorras liberadas. Una cotorra criada en cautiverio (macho, un año de edad), y liberada en el 2001, se apareó con una hembra silvestre y produjeron dos volantones en el 2004. Reduciendo la mortandad por aves rapaces informada en este estudio en un 100%, o en un 50%, resultó en tasas hipotéticas de supervivencia del 72% y 54%, respectivamente. Creemos que el adiestramiento y la aclimatación rigurosa pre-liberación mejoraron la supervivencia inicial post-liberación, y que la liberación de grupos de cotorras de edades mixtas sugiere el potencial de acortar el tiempo de reclutamiento.

The family Psittacidae is comprised of over 400 species, an ever-increasing number of which are considered threatened with extinction. In recent decades, conservation strategies for these species have increasingly employed reintroduction as a technique for reestablishing populations in previously extirpated areas. Because most Psittacines are highly social and flocking species, reintroduction efforts may face the numerical and methodological challenge of overcoming initial Allee effects during the critical establishment phase of the reintroduction. These Allee effects can result from failures to achieve adequate site fidelity, survival and flock cohesion of released individuals, thus jeopardizing the success of the reintroduction. Over the past 20 years, efforts to reestablish and augment populations of the critically endangered Puerto Rican parrot (Amazona vittata) have periodically faced the challenge of apparent Allee effects. These challenges have been mitigated via a novel release strategy designed to promote site fidelity, flock cohesion and rapid reproduction of released parrots. Efforts to date have resulted in not only the reestablishment of an additional wild population in Puerto Rico, but also the reestablishment of the species in the El Yunque National Forest following its extirpation there by the Category 5 hurricane Maria in 2017. This promising release strategy has potential applicability in reintroductions of other psittacines and highly social species in general.

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.

While most of the knowledge on invasive species focuses on their impacts, little is known about their potential positive effects on other species. Invasive ecosystem engineers can disrupt recipient environments; however, they may also facilitate access to novel resources for native species. The monk parakeet (Myiopsitta monachus) is a worldwide invader and the only parrot that builds its own communal nests, which can be used by other species. However, the ecological effects of these interspecific interactions are barely known. We compared the role of the monk parakeet as a nest-site facilitator in different rural and urban areas, both invaded and native, across three continents and eight breeding seasons. A total of 2690 nests from 42 tenant species, mostly cavity-nesting birds, were recorded in 26% of 2595 monk parakeet nests. Rural and invaded areas showed the highest abundance and richness of tenant species. Multispecies communal nests triggered interspecific aggression between the monk parakeet host and its tenants, but also a cooperative defense against predators. Despite the positive effects for native species, monk parakeets also facilitate nesting opportunities to other non-native species and may also transmit diseases to tenants, highlighting the complexity of biotic interactions in biological invasions.

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