Keep An Eye Out For These Predators–Cormorants

Editors note: Fisheries managers hold great concern for damage caused by double-crested cormorants (water turkey) and otters.  Each Fall we reprint this article as a reminder to be vigilant.  Water turkey are migratory and beginning their seasonal assault on our region. Otters are native and a continual threat.  Monitor water resources closely.  If a friend has a pond, please share this information.

Cormorants are found from southern Alaska to Mexico.  They have dark plumage and a body length 2 to 3-feet.  Webbed feet make them excellent swimmers.  They eat primarily fish and hunt by swimming and diving. Cormorants may dive 5 to 25-feet for 30 to 70-seconds.  Small fish may be consumed beneath the surface.  Larger prey often is brought to the surface before eaten.  If you’ve noticed a long scratch on fish during winter or early Spring, it may have been caused by a cormorant’s sharp beak.

This efficient predator is an opportunistic hunter.  It typically catches 2 to 6-inch fish of any species and may eat a pound or more daily.  Scout birds locate prospective feeding grounds and return with large flocks.  It’s not uncommon to see 20 or more than 100, depending on lake size.  They can significantly damage a bass forage base in a few days.  Fish farmers tell stories of entire hatchery ponds being wiped-out.  One large operation in Arkansas has almost 1,000-acres of ponds divided by levees.  Employees drive 700 to 800-miles a dayon levees attempting to chase cormorants away.

Since feathers are not fully waterproof, they spend long periods with wings extended drying feathers before flight.  Average life span is 6-years.  Once threatened by DDT, the chemical was banned.  Since the product was discontinued, numbers have increased dramatically.  Population gains are attributed to feeding opportunities at aquaculture ponds in southern wintering grounds. In flight, their v-formation resembles a flock of geese.  To accurately identify them, cormorants have longer tails and typically don’t call or communicate in flight.  Geese commonly call and have short, stubby tails.

Be aware of cormorant traffic and devise a management plan to discourage visitation. They’re bold critters. You can chase them away in the morning. They may return in a few hours. Like most migratory species, cormorants are regulated by the U.S. Fish and Wildlife Service.  There is no hunting season.  If you feel they threaten viability of your lake, contact  local game wardens or the U.S. Fish and Wildlife Service for predation permits and management options.

Otters rank next to cormorants.  They often travel with family groups and damage fish populations, especially in small ponds. Otter are the largest furry cousin of the weasel family. Their body shape is slim.  Average length is 3 to 5-feet.  Approximate weight is 15 to 30-pounds.  A flat tail about one-third its body length makes them excellent swimmers.

Otters hunt by diving and chasing fish.  They may remain under water 4-minutes and dive 60-feet.  Favored habitats are abandoned beaver huts.  They’re nocturnal and travel via creeks and rivers.  Watch for partially eaten fish carcasses on shorelines.  Observe worn paths from a creek, up the back of a dam, and into the pond.  Look for scat containing fish scales or crayfish remnants.  Scat piles are scent posts and may be large from multiple visits.  If you require services of a professional trapper, contact County Extension or Natural Resource Conservation Service agents for referrals.