There are many species of fish-eating birds around the world. Many are not normally found fishing in small bodies of water, or are found only in oceanic or polar areas. Many predatory birds do not fish in smaller ponds, possibly either due to there not being enough fish of the right size in the pond to attract them, or not enough physical space to do their normal fishing maneuvers, or their not being "wired" to recognize small ponds as a place to fish, or their not normally being found around small bodies of water, or other possible reasons. For example, it could be that birds that skim water surface (skimmers, some terns, etc.) possibly do not frequent small ponds near beaches because the water surface is not large enough for them to work, or the airways around pond are obstructed by trees, etc.
Some species, as gulls and crows, are normally scavengers, and frequent garbage dumps. They clean up dead and dying fish in our waters and along our shores and are not normally found fishing for live fish around small ponds.
Predatory birds not only eat pond fish, but can transport diseases, algae, plants, and fish eggs (a problem if from trash fish) from other bodies of water into ponds. Birds may pollute a pond with droppings if the pond is small, or if they concentrate in great numbers at ponds (this usually only occurs at aquaculture facilities). All of these possible biological additions to ponds might present potential problems for the fish in a pond.
Various injuries to pond fish, including puncture wounds, suggest a predator is targeting a pond. Also, white droppings (on ground near pond), feathers, foot prints, missing fish, or pond liner punctures are other signs of bird predation. Fish-eating birds feed during the day and can eventually be seen and identified if the pond owner is observant.
All of the fish-eating (or scavenger) birds listed herein that occur in the United States are protected by the United States Migratory Bird Treaty Act, and thus cannot be legally killed. Additional laws throughout the world may also protect them and various other species preying on pond fish, e.g.,
Provide some fish and these birds will appear. Due to the good eyesight these birds have, a body of water is quickly investigated for easy prey. Birds, like humans and other animals, will seek the easiest free lunch possible. Some can eat or remove all fish in a small pond or tank. For them it is like "fishing in a barrel." So, choose fish that are not highly visible, or expect to lose some fish. The colors of rosy-red fathead minnows, goldfish, and koi stand out so well they become easy targets.
Of the various fish-eating birds that do/might frequent small ponds, we have the following groups (based on their method of predation):
(1) Those that dive from air and catch fish with bill = kingfishers; terns and pelicans are rarely in small ponds,
(2) Those that dive from air and catch fish with feet = eagles and ospreys are rarely in small ponds,
(3) Those that dive from water surface = cormorants, mergansers, various fish-eating ducks; rarely in small ponds,
(4) Those that wade in pond; or fish from edge of pond and floating plants, etc = herons (includes egrets). Personal observations about fish-eating birds around my ponds are included in the following comments.
DIVE FROM AIR
Kingfishers (about 90 species around the world) are represented by three families: Alcedinidae (river kingfishers); Halcyonidae (tree kingfishers); and Cerylidae (water kingfishers). Kingfishers around water normally dive for small fish, but also eat insects, crayfish, and frogs. All kingfishers kill their prey by beating it against a tree or by dropping it.
The local species in my area is the Belted Kingfisher (Ceryle alcyon). It will dive into a pond and puncture the liner (40 mil HDPE in my ponds) in shallow waters (usually 8" or less), causing leaks. I have hundreds of holes along the edge of a large liner pond (12 by 60 feet by 4 feet deep) (40 mil HDPE) from kingfisher bill punctures. They were diving after rosy-red fathead minnows, and eventually got all of several thousand fish stocked out. The fatheads swam in schools around the edge of the pond, presenting themselves as easy targets.
There should be overhangs of stone or boards, or netting, etc. to protect the shallow edge areas of a pond from predation and possible liner puncture. Overhangs also give places for fish to swim and hide away from bird predation, and also provide shaded areas for water cooling. Overhangs should be high enough above the water so birds cannot stand on the overhang and reach the water to catch fish.
There may be some protection for the fish if there are no limbs overhanging the pond that the kingfishers can rest on, and dive from, to catch fish. Bird netting stretched tight over a pond/tank can discourage kingfisher predation.
Terns are represented by about 45 species found around the world. Least Terns (Sterna antillarum) have fished in my largest pond (about 150 feet long), catching smaller fish as golden shiners, mosquitofish, sailfin mollies, and the young of other species. Even though the marsh extends up the bayou from the beach to within about 800 feet from my place, terns rarely fish in my ponds, and are not considered a problem in this area for small ponds.
Pelicans are not normally found around small ponds, unless those ponds/tanks are crowded production units of aquaculture facilities, where the fish are numerous and easy to catch. Then pelicans can be a bad problem. A local fish farm raising tilapia had such a severe problem with pelicans eating up their profits (several years ago) that they resorted to shooting the birds. The birds would perch on the sides of the 30,000 gallon tanks and dive in whenever they wanted a quick meal. The fish farm owners got caught.
Ospreys (and eagles) apparently need an unknown amount of space around a pond and an unknown amount of pond water surface in order to fly in and position themselves to grab fish near the surface with their feet. From personal observation, we can probably rule them out as being a problem on the small ponds of a hobbyist, which are usually less than about 30-40 feet in diameter. Also, the larger fish they hunt and catch are not normally found in small ponds. Local ospreys teach their young to fish on my largest pond, which is about 150 feet long, and has trees at each end.
DIVE FROM WATER SURFACE
Cormorants (Phalacrocorax species) are coastal rather than oceanic, while some frequent inland waters. They are found around the world, except for the central Pacific islands. All are fish-eaters, diving from the surface and propelling themselves with their feet. Their feathers are not waterproofed, which may aid in diving quickly, since their feathers do not trap air bubbles.
Double-crested Cormorants (Phalacrocorax auritus) are numerous in Mississippi, primarily due to the easy pickings of many channel catfish ponds. In some catfish farming areas cormorants have become so numerous (from feeding on the channel catfish) that catfish losses can be 20-30 %.
Catfish farmers are now allowed to shoot cormorants at their fish farms under an order issued by the U.S. Fish and Wildlife Service in March 1998. However, some studies indicate that cormorants learn to avoid getting shot, using movements such as diving, or moving to other ponds ahead of the shooter to avoid getting shot. The cormorant problem around Mississippi fish farms is still bad.
The fish-eating ducks (as "trash ducks" like mergansers, grebes, and others) are possibly rarely found on small ponds because of the small water landing surfaces of small ponds, or the normal absence of sufficient fish of the right size to attract such birds.
WADE
Herons are wading birds in the Ardeidae family. There are more than 57 species in the world, including tiger herons, bitterns, day-herons, egrets, night-herons, and the boatbill.
In my area the Great Blue Heron (Ardea herodias) is a bad pond fish predator, using its bill to catch tadpoles, frogs, salamanders, large insects, and fish (to about 8 in). These herons usually land in a clear spot near a pond and then walk up to the edge of pond to fish from the bank or while wading in the shallows. They will walk 100 feet or more to get to a well-camouflaged pond. A friend reported that a great blue heron landed on the bricked patio around a swimming pool, walked through an arched gate down a brick path to a pond (about 6 x 12 feet) that was almost surrounded by plantings and patio/house structures to fish out the koi.
It is just a matter of time until these herons find a new pond. They can fly into a small back yard. Unless stopped, a great blue heron will come back again and again until most (or all) fish are caught out of a pond, unless you can protect the fish. If the fish caught are too large to swallow they will peck the eyes out and leave the bodies on land around pond. They are bold and not easily scared far, probably due to their being protected and not used to being harassed; they are a pond nuisance in my area.
Put plantings or fences around pond so herons cannot walk up to pond edge. Fences also serve as a safety feature against children around ponds. The edges of pond should be greater than 18 inches deep to discourage heron wading. Some great blue heron predation can be decreased by installing bird netting, or by using decoy herons to scare the herons away.
The Little Green heron (Butorides virescens) is another pond nuisance heron in my area. They can land on objects near the pond surface, including floating plants, to fish. They will fish all the mosquitofish (added to keep mosquitoes under control) out of livestock watering troughs, and unless the farmer constantly replaces the mosquitofish, these birds end up causing a public health hazard by removing the fish that help keep mosquitoes under control. I suspect they clean out small pools and ponds all around, leading to mosquito and disease problems for humans and other animals. I consider them a worse nuisance than other fish-eating birds because they endanger human life and keep on causing the extra work of constantly stocking out mosquitofish. They are hard to defend against.
Any bird netting used on a pond or tank to exclude them MUST be at least a bird's head length plus neck length away from the water because they will stick their heads through some larger mesh netting (1.25" bar mesh) to fish in a pond or tank. They can learn to land on bird netting to use their weight to get netting closer to water in order to fish through netting mesh. These birds can also learn to use bread or crackers, etc. to attract fish within striking distance.
Both the Great Egret (aka American Egret)(Ardea alba), and the smaller Snowy Egret (Egretta thula) visit the larger ponds and bayou on my place. I have never seen them around the smaller ponds, most of which have plant screens or fences around them. From personal observation, these birds like to land as close to a fishing area as possible; they don't walk as far as the great blue herons to get to the water after landing.
CONTROLPredatory bird problems should be considered when designing and building a new fish pond. Pond owners should expect visits from fish-eating birds and prepare for their control. Since the above birds are protected in the United States and many other places, we are left with the following ways to try to protect our pond fish (methods that physically exclude the birds work best; killing or trapping methods are not listed because of protection laws):
--stock out fish that are not easily visible in the pond (not brightly colored, or whitish, fish),
--cut limbs that birds can dive from that overhang pond,
--plant screens or other cover to prevent birds from getting (flying to, or walking to) to pond,
--put fencing around pond to prevent larger herons from walking up to pond (also serves as deterrent for children),
--make pond steep-sided and deeper than 18" at edges to keep wading birds out of pond,
--put overhangs around edge of pond that prevent birds from getting to fishes that like to circle ponds at edges (overhangs should be high enough off water so they will not serve as fishing platform),
--put a greenhouse around pond,
--install bird netting (keep tight) to discourage diving or wade-fishing or bank fishing birds,
--use decoys of competing large herons (to discourage other herons),
--use various noisemakers (e.g., gas exploders, fireworks, or bird distress calls) (but not too effective unless noises made at irregular intervals, come from changing directions, etc.),
--use fireworks for several evenings to disperse cormorants from their night roosts (can result in dispersed birds not going back to fishing at previous feeding sites),
--use visual devices as foil and cloth strips, flags, balloons or objects with or without eyespots, irregular flashing lights, scarecrows, and artificial decoy hawks or owls,
--use motion detector devices that spray water, or make noise, or turn on lights when activated,
--avoid using logs and rocks, etc. around/in ponds that can be used as fishing perches,
--get an aggressive dog trained to chase birds (this can be one of the best bird deterrents except when there are several ponds and the dog gets exhausted chasing the birds).
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