Understanding and Control of House Sparrows05 August 2007
By Frank T. Jones, Center of Excellence for Poultry Science, University of Arkansas
House Sparrow History and Invasion Tactics
In the 1800’s attempts were made to introduce a number of
Dr. Frank Jones
Extension Section Leader
Nevertheless, sparrows have adapted to life in close association with humans using following characteristics to successfully invade the United States and other countries: rapid reproduction; effective dispersal mechanisms; rapid, easy establishment; rapid growth and aggressive competition with other species (Zimmerman, 2007). One pair of sparrows can produce up to 20 chicks per breeding season. While unlikely, this means that one pair could potentially increase to 1,250 birds in 5 years. Sparrows are not exposed to the rigors and mortality associated with migration. Sparrows simply fly a few miles from the nest to take advantage of the nesting sites and food sources available. This steady progressing has effectively dispersed sparrow populations throughout the country. House sparrows are not finicky eaters or picky about nesting sites. They will consume virtually any food that is available and readily build nests near other bird species. House sparrows also quickly build nests 8 to 30 feet from the ground and reuse them each year. In addition, sparrows tend to feed in small flocks to avoid predation. It takes only 25 to 30 days from the time house sparrow eggs are laid to produce an independent juvenile and sexual maturity comes in 6 to 9 months. Additionally, house sparrows aggressively defend both nesting and feeding sites, destroying eggs and injuring or killing other competitive species. House sparrows are persistent, resourceful and intelligent. In fact, Fitzwater (1994b) reports that the brain usually accounts for about 4.3% of the body weight of sparrows, which is considerable more than those of other birds.
House Sparrow Biology
Sparrows (pictured above) are generally about 5.75 inches in total length and have brown plumage. Sexually mature males have a black striped back, gray on the crown of the head and a characteristic black “bib” or stripe on their throat. Females and young are brown with striped backs and a pale tan “eye brow” or stripe over their eyes (Kern, 2001).
Sparrows tend to be “home bodies,” spending their entire life 2 to 3 miles from their roosts and feeding sites (Casto, 2001). Plant materials (grain, fruit, seeds and garden plants) make up 96% of the adult diet but young are fed insects until they are almost grown (Fitzwater, 1994a; Kern, 2001). However, sparrows are known to eat more than 830 foods and commonly use the same nesting site year after year (Casto, 2001).
Nests of sparrows are usually an untidy mass of dried grass, leaves, pine straw, string, paper and feathers, usually positioned 8-30 feet off the ground for protection from predators (Kern, 2001; Zimmerman, 2005). Nesting sites are usually claimed by the males in mid to late winter, prior to courtship in late winter or early spring (Eno, 1996). Both males and females participate in nest building, but females supply the majority of construction activity. Nest building may begin just a few days before the first egg (Zimmerman, 2005). About 90% of adults stay within a radius of 1.25 mi during nesting (Fitzwater, 1994a).
Sparrows are monogamous, but appear more closely bonded to a nest site than a mate. Males spend 60% of their perching time at nesting sites during breeding season. Males with wide bib sizes mate more often than those with narrower bibs, and aggressively defend nest sites mostly from other male sparrows (Zimmerman, 2005).
Egg laying starts in March or April usually with 3 to 4 clutches of an average of 5 speckled white eggs. Studies have shown that in a suburban setting 67% of house sparrow eggs were infected with E. coli pathogenic to avian species (Pinowski et al., 1994).
Eggs are incubated by both males and females for 10-16 days and the young remain in the nest about 15 days (Casto, 2001; Kern, 2001). Females take the primary responsibility for raising nestlings, visiting the young 15-19 times per hour, but both parents feed young by regurgitation. Fledglings are able to feed themselves 7-10 days after leaving the nest. After fledging, birds may wander 0.6 – 1.2 mi to find new feeding areas (Zimmerman, 2005).
Predators, disease and stress cause heavy sparrow mortality during the first year of life and few birds survive past the fifth season, but the typical lifespan of 3 years is relatively long in comparison to other species. However, individual birds have been found to live up to 11 years in the wild (Casto, 2001; Fitzwater, 1994a, Zimmerman, 2007).
Concerns about House Sparrows
House sparrows are often hated by bird lovers and some call them “flying rats” or “weeds of the air.” Bluebird and purple martin lovers are particularly venomous toward house sparrows because they effectively (sometimes brutally) compete for nesting and feeding sites (Van Vleck, 1994).
Sparrows have also been reported to carry:
- Bacterial diseases that can affect both humans and animals like salmonellosis (Whitney, 2004) and perhaps anthrax;
- Mycoplasma diseases including such as Mycoplasma gallisepticum (MG), which is pathogenic to many avian species (including poultry);
- Protozoan diseases such as sarcosporidiosis, and coccidiosis, which affect primarily animals as well as toxoplasmosis, and chlamydiosis (psittacosis) which are maladies in both humans and animals
- Viral diseases such as West Nile Virus, Eastern Equine Encephalitis (EEE), Western Equine Enchephalitis (WEE), St. Louis Encephalitis, and Venezuelan Encephalitis which infect humans and animals via mosquitos; Poultry diseases such as Newcastle disease or fowl pox and TGE in swine;
- Internal parasites such as round worms, tape worms, gape worms; and
- External parasites such as fleas, ticks, mites (including the northern fowl mite), bed bugs and lice.
External parasite populations are readily propagated by sparrow populations since nests are unkempt and reused (Kern, 2001; Fitzwater, 1994a; Zimmerman, 2005). In addition, nesting materials may cause fire hazards when constructed near lights or other heat sources (Kern, 2001).
Sparrow Control Methods
Although sparrows are a nuisance as well as spreading disease organisms and parasites, their close association with humans limits safe alternatives for control. However, control methods can be divided into the following seven categories: exclusion, repellants, poisons, trapping, shooting, nest destruction and predators (Fitzwater, 1994a).
Since sparrows are intelligent, hardy and adaptable, total exclusion is virtually impossible. In addition, exclusion efforts must be sustained over long periods to be effective. Nevertheless, closing all openings of 0.75 inches or larger, covering large openings (such as under eaves) with hardware cloth, and attaching signs flat against buildings can assist in control of sparrows. It is also important to cover any source of grain or food to prevent access by sparrows.
There are two general types of sparrow repellant systems: tactile and sound repellants. Tactile repellants are those that are placed on roosting or nesting surfaces to discourage sparrow activity. Unfortunately tactile repellants (such as electrified wire, porcupine wire or sticky substances) are generally more effective against pigeons than sparrows. Sound repellants (such as loud noises from fireworks or firearms; ultrasonic devices or recorded distress calls) may discourage sparrows for a time, but usually they learn to ignore the sounds (Fitzwater, 1994a; Kern, 2001).
Poisons used to control sparrow populations are restricted use pesticides that are regulated by both federal and state laws. Considerable skill is required to ensure that these poisons do not affect humans. The use of poisons will also require considerable study of sparrow nesting, roosting and feeding sites and can have very serious unintended consequences. Remember that most bird species are legally protected by state laws, federal laws and international treaties. The person using poisons as a control method is legally responsible for the consequences (intended or not). In addition, poisons that affect sparrows may have similar affect on poultry species and/or could produce residues in poultry products.
While trapping of sparrows is often more labor intensive and expensive than other control methods, trapping can effectively reduce sparrow populations. In addition, since most traps are live traps, if birds other than sparrows are caught, they can be quickly released. Yet, no matter what trap is used, the secret to trapping is to put out bait (pre-bait) about a week before setting traps (Kern, 2001). It is also important to use the right bait. Fitzwater (1994b) developed the data in Table 1, which show that sparrows preferentially consume white millet, corn cracked to 1/16 to 4/16 inch in size or whole milo.
|Table. 1. Preference shown by sparrows for eight candidate bait materials¹|
Material Taken In 24 Hours
|Grams Taken||Percent Of Total|
(1/16 to 2/16”)
(2/16 to 4/16”)
|1 Adapted from Fitzwater (1994b)|
There are more types of traps available for sparrows than for any other bird, making it impractical to attempt to describe every model (Fitzwater, 1994a). Still there are a few general types of traps, each of which have pluses and minuses.
Funnel or drop-in traps are the most common type of sparrow trap and can accommodate a sizable number of birds. Funnel traps employ a funnel or trough shaped entrance that allows sparrows to easily pass through the large end into the trap, but the small end inside the trap discourages exits. Funnel traps can capture relatively large numbers of sparrows, but they can also escape with relative ease. Therefore, it is important to frequently check funnel type traps (Fitzwater, 1994a; Kern, 2001)
Although there are numerous design variations; automatic, counter balanced, or elevator traps that allow a sparrow to enter an enclosed compartment attached to the end of a holding cage. The sparrow enters to get the bait, which is on a small box inside the compartment. The box is enclosed on two sides with the entrance to the cage below. The shelf or box is attached to the end of rod or narrow thin board that pivots around a fulcrum in the center, similar to a see-saw. A counter weight balances the box, and as the sparrow consumes the bait, its weight causes the rod (or see-saw) to tip downward closing off the original entrance and, when the rod reaches the bottom, exposing the entrance to the holding cage. The sparrow enters the holding cage and the counter weight returns the box to its original position. Elevator traps tend to catch fewer birds than funnel traps, but the birds that are caught generally do not escape (Fitzwater, 1994a).
Triggered traps are snares that generally catch one sparrow at a time and usually involve a spring operated door or closure. Sparrows enter the trap, trigger the closing of the door and are trapped. Obviously this type of trap catches only one or maybe two sparrows at a time. Thus, such traps are not suited for controlling large populations, but may be effective against a few persistent individual birds.
Shooting with firearms
Since rifle slugs can travel over a mile and penetrate tin, drywall, plywood or other such materials, it may be wise to use air guns, a 410 gauge shotgun with a no. 10 to 12 size shot or a 22 rifle with rat shot. Such weapons may be an effective method of controlling a few sparrows in a relatively small area, but are ineffective at controlling large numbers of birds. Furthermore, such weapons can become increasingly ineffective when sparrows become wary.
Sparrow populations will continue to increase if nests are allowed to remain. Removal of nests, eggs and young tends to discourage birds from building. However, sparrows are persistent and nest removal must be repeated every two weeks during breeding season. Long insulated poles may be used to remove nests from high places and destroyed to prevent reuse. In addition, nesting materials may be infested with external parasites (especially mites) and infected with disease organisms.
Both cats and sparrows often live in symbiotic relationships with humans. One farmer used scrap lumber to build cat walks between exposed rafters where sparrows usually roosted or nested. These makeshift walks, allowed farm cats access to locations where sparrows usually roosted or nested and resulted in a reduction of the resident house sparrow population by 80% over the course of a year.
House sparrows are not native to the United States and in most cases are not protected by federal or state laws. House sparrows are intelligent, persistent and resourceful. However, house sparrows can destroy insulation, cause fire hazards with nesting materials as well as spread disease and parasites. Control of house sparrows may be accomplished through exclusion, repellants, poisons, trapping, shooting, nest destruction and predators (e.g. cats). However, control efforts must be consistent, diverse and organized. In addition, it is important to keep in mind that control efforts should not compromise flock performance or produce residues in poultry meat or eggs.
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