Leach's Storm-Petrels (Hydrobates leucorhous) are burrow-nesting seabirds that breed on coastal islands throughout much of the North Atlantic, with most of the world's population breeding in Atlantic Canada. Population declines in the past 20-30 years have resulted in the species being uplisted to "Vulnerable" on the International Union for the Conservation of Nature Red List of Threatened Species. One of the species' most well-studied colonies is on Kent Island, New Brunswick in the Bay of Fundy. To determine if this colony has faced declines over a similar timescale, census work was conducted in June and July of 2000/2001 and 2018. Forty-one east-west transects in 2000/2001 (516 plots) and 56 east to west transects in 2018 (678 plots) were established every 50 m along the length of the island, which were censused with 10 m² plots. Population estimates were calculated by extrapolating mean occupied burrow density over the area of suitable nesting habitat on the island. Additionally, habitat characteristics and predator presence were recorded within each plot, and classification and regression tree (CART) analysis was used to determine which environmental factors affected burrow densities and occupancy rate. The estimated number of breeding pairs for the entire island in 2018 was 21,643 (CI 16,942-26,343) and has declined at an annual rate of-1.79% (CI-3.28% to-0.25%) since 2000/2001 (29,416 CI 23,015-35,817 pairs), though population trends varied across the island with forested habitat experiencing a large decline and the open habitat experiencing a marginal increase. CART models revealed that occupied burrow densities were highest in areas dominated by ferns or shrub/bramble that had no signs of forest regrowth, and had low gull nesting densities. Our results suggest that Leach's Storm-Petrels are declining at the southern extent of their range at similar rates exhibited at northern colonies, especially in forested habitat where habitat change may be influencing nest-site use. Déclin de la reproduction de la population et associations avec l'utilisation des sites de nidification des pétrels cul-blanc sur Kent Island, dans le Nouveau-Brunswick, de 2001 à 2018 RÉSUMÉ. Les pétrels cul-blanc (Hydrobates leucorhous) sont des oiseaux marins nichant dans des terriers, qui se reproduisent sur les îles côtières le long d'une grande partie de la côte nord-Atlantique, principalement le long de la côte Atlantique du Canada. Leur population a décliné au cours de 20 à 30 dernières années, de sorte que cette espèce est désormais classée comme « vulnérable » sur la Liste rouge des espèces menacées de Union Internationale pour la Conservation de la Nature. L'une des colonies les plus étudiées de cette espèce habite Kent Island, dans le Nouveau-Brunswick, dans la baie de Fundy. Pour déterminer si cette colonie a décliné au cours de la même période, un recensement a été effectué en juin et juillet 2000/2001 et 2018. Quarante-et-un transects est-ouest en 2000/2001 (516 parcelles) et 56 transects est-ouest en 2018 (678 parcelles) é...