The double‑crested cormorant’s numbers fell sharply in the 1960s because of DDT exposure. Once threatened by the use of DDT, the numbers of this bird have increased markedly in recent years. Recent studies attribute the rebound to the cessation of DDT use and possibly to expanded aquaculture habitats. While the upward trend is clear, exact population counts across its vast range remain incomplete, and the relative influence of each factor is still debated among researchers.
Edition
Population rebounded after DDT ban
Once devastated by the pesticide DDT in the 1960s, the species has shown a marked increase in numbers since the chemical’s discontinuation, illustrating a successful environmental recovery.
Sources behind this fact
Links were checked independently of editorial approval. A healthy link confirms availability, not the truth of every statement on the page.
- unknown
Double-crested cormorant
Wikipedia · reference work
Where: Double-crested cormorant
Quote: "Once threatened by the use of DDT, the numbers of this bird have increased markedly in recent years."
Accessed October 4, 2026 · automated link check pending
- unknown
Double-crested cormorant
Wikipedia · reference work
Where: Double-crested cormorant
Quote: "Recently the population of double-crested cormorants has increased."
Accessed October 4, 2026 · automated link check pending
- unknown
Double-crested cormorant
Wikipedia · reference work
Where: Double-crested cormorant
Quote: "The double-crested cormorant's numbers decreased in the 1960s due to the effects of DDT."
Accessed October 4, 2026 · automated link check pending