The familiar chorus of songbirds that once filled Acadia National Park’s forests has grown noticeably quieter over the past several decades, according to recent research. Scientists found that several key bird species have declined or disappeared, while the overall volume and diversity of bird calls have diminished, signaling a significant shift in the park’s ecosystem linked to rapid climate warming.
Research conducted in 2025 by a fellow at the Schoodic Institute replicated bird surveys first done in 1959. The data revealed a sharp decline in species that were once common, including the bay-breasted warbler and olive-sided flycatcher, which are now absent. Other species, such as the Swainson’s thrush, known for its flute-like song, have become less frequent, replaced by more common but less melodious birds like the red-breasted nuthatch. Even the black-throated green warbler, Acadia’s most prevalent bird decades ago, is now heard far less often.
These changes may go unnoticed by casual visitors due to a phenomenon called shifting baseline syndrome, where people accept the current, diminished soundscape as normal without realizing how much biodiversity has been lost. To long-time researchers, however, the forest sounds markedly less alive.
Experts attribute this decline primarily to climate change. The Gulf of Maine historically provided a cooling effect, preserving ecosystems suited to cold-adapted trees such as red spruce and balsam fir. But the gulf’s waters are warming at nearly three times the global average, diminishing this natural air conditioning and threatening these coastal forests.
A 2024 National Park Service report predicts that by mid-century, Acadia’s average temperatures could rise by up to 8 degrees Fahrenheit. While this warming does not directly harm most songbirds, it disrupts the timing of insect emergence and plant growth integral to bird breeding and feeding cycles. Such mismatches can result in food shortages during critical periods, undermining bird populations over time.