Economic estimates of invasive wild ungulate damage to livestock producers in Hawai'i.

BACKGROUND: Invasive ungulates (hoofed mammals), including deer, feral pigs, feral goats, and feral sheep, are known to cause damage to agriculture, property, natural resources, and many other commodities. Most of the information regarding the economic impacts of wild ungulates is from North America, where some of these species are native. To evaluate invasive ungulate damage to livestock producers in the Hawaiian Islands, which have no native ungulates, a survey was distributed to livestock producers across the state. RESULTS: Survey results described how total annual costs are distributed among damage, control, and repairs for survey respondents, who represented a significant percentage of total ranchland acreage across the islands. The estimates, excluding fixed fence installation, revealed an annual cost to livestock producers who responded to the survey of US$1.42 million, which ranged from $3.6 million to $7.5 million when extrapolated to the entire state. The large cost contributors included damage to property, pastureland repair, control costs (excluding fencing), supplemental feed, and predation of calves by wild pigs. Additionally, producers reported spending more than $2 million in upfront fence installation costs. Most of these costs were reported by respondents on the islands of Hawai'i and Moloka'i. CONCLUSION: Study results revealed substantial damage to state livestock producers due to wild ungulates and are useful in determining an invasive ungulate management strategy that can appropriately aid the most impacted sectors of Hawai'i. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Predation of the endangered Ae'o (Hawaiian Stilt) by a native raptor, the Pueo (Hawaiian Short-eared Owl) on the island of O'ahu, Hawai'i, USA.

While the impact of introduced predators is a widely acknowledged issue and key component of conservation considerations for endemic waterbird populations in the Hawaiian Islands, the impact of native predators on endemic, endangered waterbirds is not as frequently discussed or factored into recovery models. The Pueo (Hawaiian Short-eared Owl; Asio flammeus sandwichensis) is a subspecies of Short-eared Owl endemic to the Hawaiian Islands and is State-listed as Endangered on the island of O'ahu. The Ae'o (Hawaiian Stilt; Himantopus mexicanus knudensi) is a subspecies of the Black-necked Stilt endemic to Hawai'i and is federally listed as Endangered throughout its range. A variety of non-native predators are confirmed to consume Ae'o eggs, chicks, and adults, including invasive mammals (e.g., feral cats), birds (e.g., Barn Owls), and amphibians (e.g., bullfrogs). While predation by native predators was suspected, there are no cases documented in the literature to date describing Pueo preying upon Ae'o. Here, we describe four events that provide evidence of Pueo predating Ae'o during the 2019-2021 breeding seasons in a wetland area on the island of O'ahu: (1) confirmed Pueo predating an Ae'o chick, (2) a suspected predation attempt of a Pueo chasing adult Ae'o, and (3) two suspected predation events based on (a) 10 adult-sized Ae'o carcasses and remains found near an active Pueo nest and (b) game camera photos of Pueo visiting two Ae'o nests. To our knowledge, these novel observations are the first published accounts of predator-prey interactions between these two subspecies.