Breeding on a Tropical Island Proves More Difficult Than Expected: The Ongoing Breeding Failure of Laysan Albatross on Clarion Island.

In the 1980s, the Laysan Albatross (Phoebastria immutabilis) expanded its breeding range into the eastern Pacific and established colonies on several islands off the coast of Mexico. Colony growth has varied widely among these islands, likely reflecting differences in immigration rates and local conditions, such as food availability and predation risk, which can influence breeding success and population dynamics. We assessed the breeding performance of Laysan Albatrosses on Clarion Island (2016-2023) in relation to foraging ecology and local predation. We monitored breeding success through periodic nest checks and quantified predation rates through focal observations. We tracked foraging trips using GPS devices and analyzed blood samples for stable isotopes (δ 15N, δ 13C). Over the study period, the colony experienced complete breeding failure. Our results suggest that two factors likely contributed to this outcome: (1) foraging limitations and (2) high predation rates. The remote location of Clarion Island required Laysan Albatrosses to travel farther to feeding grounds, potentially reducing the time available to acquire high-quality prey. This may have influenced their dietary δ13C signatures, which were associated with hatching success in our study. In addition, hatchlings experienced extremely high predation. Together, the apparent foraging constraints and intense local predation hindered successful reproduction and local recruitment. These factors may help explain the limited growth of the Clarion colony over recent decades. This study provides baseline data on the status of the colony and its main threats, which serve as critical input for planning conservation and management strategies.