Reproductive success of Mariana Swiftlets (Aerodramus bartschi) on the Hawaiian island of O'ahu

Abstract

Mariana Swiftlets (Aerodramus bartschi) are federally listed as endangered, with populations currently limited to just three islands in the Mariana Islands plus an introduced population on the Hawaiian island of O'ahu. Before efforts are made to reintroduce Mariana Swiftlets to other islands in the Mariana archipelago, additional information is needed concerning their breeding biology. Therefore, our objective was to examine the reproductive biology of Mariana Swiftlets over five annual cycles on the Hawaiian island of O'ahu. This introduced population used a human‐made tunnel for roosting and nesting, and was studied as a surrogate to negate interference with endangered populations in the Mariana Islands. Active nests (N = 478) were observed in every month of the year, with peak nesting activity between May and September. All clutches consisted of one egg. Mean duration of incubation and nestling periods were 23.9 d (range = 18–30 d, N = 233) and 55.0 d (range = 41–84 d, N = 228), respectively. Estimated nest success was 63%. Over half (52%) of nest failures were attributed to eggs found on the tunnel floor. Predation by rats (Rattus spp.) was also an important cause of nest failure and often resulted in the loss of most active nests. However, Mariana Swiftlets did re‐nest after these predation events. Our results suggest that rat predation of both nests and adults may limit growth of the Mariana Swiftlet population on O'ahu, and could also affect the chances for successful establishment of relocated populations in the Mariana Islands. Another limiting factor on O'ahu is that only one nesting site is apparently available on the island. Current goals for downlisting Mariana Swiftlets from endangered to threatened include establishing populations on Guam, Rota, Aguiguan, and Saipan. To meet these goals, the population of Mariana Swiftlets on O'ahu can be important for testing reintroduction techniques, learning more about the natural history of these swiftlets, and providing individuals for reintroduction efforts in the Mariana Islands.

Saving two birds with one stone: solving the quandary of introduced, threatened species

“…This swiftlet was deliberately introduced to Oahu, Hawaii, where it later established a small population. The Hawaiian population has proved to be a useful surrogate for research into the ecology and natural history of the species and has been the focus of intensive study in recent years (eg Wiles and Woodside 1999), thereby facilitating conservation efforts targeting the swiftlet in its native range (Johnson 2015).…”

Tissue-engineered edible bird’s nests (TeeBN)

“…The annual export volume from major producing countries in Southeast Asia exceeds 3,000 tons ( Figure 1A ). Excessive harvesting and unsustainable farming irreversibly damage the environment, rendering 4 million birds homeless and endangering certain swallow species [ 6 , 7 ] . Also, natural EBNs on the market are often detected with toxic heavy metal salts and microbial contamination [ 8 ] .…”