island

Avian reproduction is a process that requires extensive energetic input by parents, particularly in pelagic seabirds. Parental infanticide has rarely been reported in pelagic seabirds, and its frequency among taxa is therefore difficult to determine. Using data from remote cameras, two cases of probable parental infanticide in Red-billed Tropicbirds Phaethon aethereus were captured on Sint Eustatius in the 2021–2022 breeding season. Both cases are presented with images collected from remote cameras as evidence. While appearing counterproductive, parental infanticide may provide an alternative reproduction strategy that favors lifetime reproductive success over short term success.

Red-billed Tropicbirds breeding on Pilot Hill on the island of Sint Eustatius have been exhibiting an average survival rate of between 30-40%. The influence of nest cavity attributes, environmental covariates, and parent behavior on Red-billed Tropicbird survival were evaluated through nest surveys and camera trap data. Daily survival rate was calculated as a function of selected covariates. Time spent away from the nest by parents and minimum temperature were the most influential factors. Nest attributes and temperature variables did not correlate to survival. 

Abstract

The Invasive Alien Green Iguana (IAGI), Iguana iguana, has spread worldwide via the pet trade, as stowaways and via other means and has become a pest species of global concern. It also represents a major threat to the endemic Lesser Antillean Iguana, Iguana delicatissima, on St. Eustatius. Following the capture of an adult female IAGI on St. Eustatius in early 2016, we conducted a Rapid Response Removal Campaign (RC) from April 2016 to January 2017. Three sets of directed visual surveys totaling 409.5 observer hours and covering a combined trajectory of 114.2 km realized only a single detection of a hybrid that was later removed. During the remainder of the campaign period, an additional four IAGI hybrids were opportunistically detected and removed thanks to park staff or community involvement. Since the end of the campaign, eight additional detections and removals have been realized, three of which were IAGIs caught while offloading freight in the harbour and five of which were hybrids caught in surrounding suburban areas. We suggest that at least four distinct IAGI introductions to St. Eustatius occurred between 2013 and 2020. Our results show the value of motivating and mobilizing stakeholders and the public at an early stage of an invasion. Since the program’s initiation, eight of the 13 iguanas detected for culling were thanks to public and key stakeholder support and involvement. Four years after our campaign, the number of IAGIs and their hybrids still appear to be limited and concentrated in and around inhabited areas. Additional removal campaigns should be initiated as soon as possible, firmly based in public outreach, motivation and engagement. New legislation is needed to prohibit the importation, possession and harbouring of IAGIs or hybrids and to provide a framework for long-term structural funding required for effective control and removal. Routine fumigation and rigorous inspection of arriving cargo to eliminate the risk of stowaway IAGIs are also recommended. Culling of IAGIs is recommended for the port of St. Maarten, which serves as a major point of dispersal of IAGIs to St. Eustatius and likely also other islands in the region.