The Problem With Cormorants

The Double-crested Cormorant is a member of a family of aquatic birds commonly referred to as "shags". These large birds can grow up to 90 centimetres and weigh as much as 2500 grams or 5.5 pounds. They feed almost exclusively on small fish and are considered opportunistic predators, taking advantage of a range of aquatic habitats from estuaries to brackish or freshwater marshes. 

Cormorant Plumage
WhatBird.com

Adults are bronze-black with the exception of a patch of bare orange skin on the face that extends along the lower mandible. They are named after the two white or black crests (facetiously referred to as eyebrows) that are grown during breeding season.

These birds prefer to winter outside of the province but return every spring where they build nests on the ground out of small sticks, reeds, and leaf litter. Double-crested cormorants are very social birds and often nest in large groups with each nest capable of producing up to 7 unmarked pale eggs.

Nesting Site on a small island near Port aux Basques 

The Double-crested Cormorant suffered from eggshell thinning as a result of being exposed to the man-made chemical, dichlorodiphenyltrichloroethane (DDT) in the 70s and experienced a population crash that led many to believe that the species was well on its way to extinction.

The species recovered, with numbers exploding over the past 15 years. A feat likely attributed to the ban on DDT and their protection under the Migratory Bird Treaty Act in other countries.

This boom has been covered extensively in the media, with Ontario announcing a cull of the species in 2020. Newfoundland followed suit and, on June 1, announced their own cull slated to begin later in the month. The decision to interfere with this species has left people divided on the subject, with many wondering why the government would want to selectively slaughter these large aquatic birds.

Double-crested Cormorant taking down a massive fish.
Photo by Alex McInnis

If you ask outdoorsmen, they'll tell you that the shags are damaging fish stocks, and they're probably right. While it varies from day to day, an individual cormorant can easily consume over 500 grams of fish per day. If you've seen a large colony of these birds, you'll quickly realize how devastating this could be for young salmon or trout.

To make matters worse, cormorant guano (or feces) is detrimental to the vegetation and soil composition surrounding nesting sites and may even interfere with other sea bird breeding and nesting activity.

The governments answer to this is to "...allow the humane, lethal removal of birds from specific areas, such as important fish habitat, water supplies, or aquaculture operations". The province will continue to survey colonies across the island and assess their impact on local ecosystems.

Cormorant drying off after being in the water.
Photo by  Harold Weldon Bradley

If you would like to see a Double-crested Cormorant, visit your local pond, river, or shipyard. You'll often see them drying their massive prehistoric wings on-top of rocks or lampposts after a successful dive.