The establishment threat of the obligate brood-parasitic Pin-tailed Whydah (Vidua macroura) in North America and the Antilles

Abstract

The Pin-tailed Whydah (Vidua macroura) is a generalist obligate brood parasitic bird native to Africa, frequently found in the pet trade, which has successfully established exotic populations in 2 biodiversity hotspots in the Americas. We analyze the species' potential future distribution by identifying key locations in the continental United States, Hawaii, and the Antilles that contain suitable climatic characteristics, host species, and habitat requirements. We used species distribution modeling (MaxEnt) to depict the geographic patterns of possible Pin-tailed Whydah establishment and compared the predictive power of models that included combinations of climatic data (''climate''), land cover (''habitat''), and localities of historical and one known novel host (''hosts''). The preferred model, the ''hosts'' model, was the highest performing. The most important variable characterizing Pin-tailed Whydah distribution in the preferred model was the presence of a frequent historical host that is also established in the Americas, the Common Waxbill (Estrilda astrild), followed by a less frequent historical host, the Bronze Mannikin (Spermestes cucullata). Our research demonstrates that in the continental United States, Hawaii, and the Antilles, there are locations that possess the needed exotic host species that may facilitate further invasion by the Pin-tailed Whydah. Given that Pin-tailed Whydahs are known to exploit .20 host species from 4 families of birds, clear next steps include assessing their ability to parasitize novel, native species within the highly suitable areas identified in this research.