Cerulean Warbler

The aptly named Cerulean Warbler is one of the rarest breeding species in New Hampshire. It wasn’t even known to occur here regularly until the 1990s, when a small population was discovered in Pawtuckaway State Park. Around the same time there were irregular records from Mount Wantastiquet in Chesterfield and Hinsdale in the southwest corner of the state, and a couple of records from along the Blackwater River in Salisbury. Pawtuckaway was by far the most reliable site, hosting up to at least 4-5 males in some years, but around 2010 the species started to become less reliable there and appears to have disappeared entirely. Over that same time, reports increased from Wantastiquet, although this may in part be due to more intensive birder visitation. The species has been almost annual there since 2020. If searching for it, be aware that local Black-throated Blue Warblers can sing a song almost identical to that of a Cerulean, and sight records are required for confirming records anywhere in the state.

New Hampshire is at the extreme northeastern corner of the Cerulean Warbler’s range, which is centered on hardwood forests of the Appalachians and Midwest. Across most of this range it has been in decline for over 50 years, leading to extensive study of its habitat and migration. Researchers have found that Ceruleans prefer forests with high canopies and diverse mixes of tree heights in the understory, and in the core range several projects have implemented forestry practices to improve forest structure for the species. This warbler winters in mid-elevation forests of the northern Andes in South America, an area subject to high human pressures such as deforestation for agriculture. To this end, conservation groups have initiated land protection efforts in the non-breeding range, initiatives that also benefit native resident wildlife.