by: Erin Schoenfuss

Interactions


Tree Swallows interact with a diverse array of organisms both predatory and benign.  They interact with organisms through everyday life of competition of nest sites, predation, ectoparasites, and interaction with the environment.  Tree Swallows’ high reproduction rate helps make up for loses from predation, disease, and weather.
 
                   Other Organisms That Tree Swallows Interact With
                   
Predators
                   
Disease
                   
Competition with Other Birds
                   
Competition with Other Tree Swallows
                   
Environment
                   
Humans


Other Organisms That Tree Swallows Interact With
 

Tree Swallows live along side an array of different organisms. Many include white-tail deer, squirrels, chipmunks, monarch butterflies, turkeys, brown-headed cowbirds, red winged black birds, cardinals, baltimore orioles, ruby-throated hummingbirds, yellow finches, purple finches, house wrens, blue birds, robins, blue jays, house sparrows, chickadees, and many others.  They also live with a variety of tree species in which they build their nests inside and various other plant species.

 


Predators
 

Like for all creatures, predation is a way of everyday life for Tree Swallows.  Like was already mentioned, high reproduction rates help make up for losses.  In fact, most losses occur at the time when the young leave the nest.  This occurs because they are weak and inexperienced which makes them easy prey. For those that make it to adulthood must fight to survive and must become strong and fit for their own good.  If they do not they will not survive.

Some of the biggest predators to Tree Swallows are domestic cats, hawks, kestrels, snakes, raccoons, opossums, weasels, squirrels, black birds, and many more.  These organisms will capture and eat adult tree swallows and will kill their young or eggs right from the nest.  Even the most adept adult flyers can be attacked and killed by hawks and kestrels.

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Disease
 

Like other birds, Tree Swallows can be susceptible to a whole variety of diseases The disease can be caused by bacteria, protozoa, viruses, or ectoparasites.  West Nile Virus can even affect Tree Swallows.  Others could be susceptible to disease due to wasp stings, ectoparasite infestation, birth defects, environmental factors, or injury.

Young nestlings are weak and may not be able to cope with parasites that raid the nest.  These ectoparasites, parasites found outside of the body, include blowfly larvae, fleas, lice, and mites.  The picture on the right shows an example of a bird louse.  They affect adult TreeFile:Fahrenholzia pinnata.JPG Swallows as well, but death usually results indirectly when these ectoparasites are brushed off the adults and land on the nestlings.  These parasites indirectly cause death to nestlings because they don’t just kill the babies out of the blue, but they weaken their immune system making them very susceptible to contracting all sorts of disease.

Many times Tree Swallow nests will be infested with ectoparasites.  Blowflies and mites pose problems because they suck the blood of the infected individual.  They are easily transmitted from adults to the young because they are always in contact with each other.   Mites in fact can jump from individual to individual.


Competition with Other Birds
 

Competition is high for all birds, but for Tree Swallows it is especially hard when available cavities are limited.  Their biggest competition comes from European starlings, house sparrows, house wrens, and bluebirds, but they will even compete for nest sites with chickadees, owls, and kestrels.  All these species nest in cavities as well and will take Tree Swallow’s nest sites at all costs.  Many of these species will kill the adults, kill their eggs, and kill the hatched nestlings.

Sometimes, because Tree Swallows can be very small compared to other birds, bigger birds like starlings, owls, and kestrels will not be able to raid the nest because they will not be able to enter some of the entrances to the cavities.  This is the main reason why when building a birdhouse you make the entrance hole 1 inches in diameter.  This will lower the competition for tree swallows.

But, you will have birds that will be able to get into these entrance holes.  wrens, house sparrows, and bluebirds are able to do just that.  Bluebirds are much larger than Tree Swallows and can cause damage.  They will destroy the nest and will outcompete Tree Swallows.  Wrens, even though small, can cause their damage by removing or destroying Tree Swallow eggs. House sparrows compete by killing adult Tree Swallows and building their nests over top of the Tree Swallows nest.

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Competition with Other Tree Swallows
 
Just as Tree Swallows compete with other species of birds, they also compete with those within their own species. Pairs will compete with each other for nest sites and many will die in the battle.   Commonly, birds will compete for nest sites even when territories have been established.  Many times adults that are not in pairs will kill nestlings when they want to take over that nest.


Male tree swallows, when they want to replace a dead male, will kill all the former young in that nest.  By killing these young the male tree swallow will be able to have his own children and reduce competition in the future from the other male Tree Swallow’s children. Female Tree Swallows may do the same so they can get nest sites.

Environment
 

The environment can be very rough on any creature.  Tree Swallows may be threatened by environmental affects causing hypothermia or starvation.  If it is raining constantly during the spring or summer, it can get cold and wet very quickly and will affect these birds extremely.  On top of that if it is windy, available insects that Tree Swallows feed on could be lowered.  This would not only cause starvation in the adult Tree Swallows but will inadvertently cause starvation and hypothermia in their young. 

Both parents bring food to the hatched young and if one parent dies, the other parent must fend for all the babies.  If there is a case when all six babies survive after hatching that parent has a huge burden on their shoulders.  Because one parent is not able to feed all the nestlings by themselves, the weakest will starve.  In hope, the stronger young will live. 

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Humans
 

Just as the environment may be affected by File:AlfedPalmersmokestacks.jpghumans, so too can those organisms that live in it.  Many times Tree Swallows, like other organisms, can be poisoned or killed when their food supply is contaminated by pesticides or pollutants.  Sometimes, if people bother the nests too much the parents could even desert the nests do avoid danger on themselves.  When nest sites are built too close to roads, as they take away much of its habitat, Tree Swallows could be threatened by collisions with automobiles.

         

  
By clicking Other Related Species you can learn about the other species under the genus Tachycineta.  Click here to return return to the Tree Swallow:Tachycineta bicolor Homepage.