Learn About Birds at Tree Swallow Nest Box Projects
Tree Swallow Research

Has much scientific research been conducted on Tree Swallows?
Ready for a surprise?  The species of choice for many North American
ornithologists pursuing songbird research is - - - the Tree Swallow!













Very few people outside the professional ornithological community are aware of
the important contributions of Tree Swallows to scientific research.  Over 400
professional journal articles that focused on or used Tree Swallows as
experimental subjects have been published since 1980.  This is far more than for
bluebirds, robins, cardinals, and chickadees - combined!  (Please note: we are
referring to scientific articles, not anecdotes in birding or hobbyist magazines,
which though interesting are not subjected to rigorous scientific standards).  
Some ornithologists have gone so far as to state the Tree Swallow should be
acknowledged a "model species" for the significance of its role in biological,
ecological and behavioral research on birds.  For many ornithologist they are the
songbird equivalent of fruit flies, nematode worms, zebra fish, and lab mice.  
Not a very glamorous group you say?  Maybe not, but important?  Very!







What makes Tree Swallows such valuable research subjects?
Ornithologists have found, as you are finding, that Tree Swallows offer great
opportunities for learning because:
  • Tree Swallows are easily attracted to nest boxes, and will nest relatively
    near one another.
  • Research grids with hundreds of nesting pairs can be established, giving
    scientists the large sample sizes needed for valid conclusions.
  • Box nesting allows many conditions to be standardized or manipulated
    experimentally, and box-nesting Tree Swallows are much easier to trap
    than open-nesting birds.
  • These swallows have good return rates and ease of recapture which
    allows experimental variables to be tracked and measured over time.
  • Swallows can be uniquely marked for ease of recognition in the field.
  • They can be captured, handled, and tested with low risk of desertion.
  • Much of Tree Swallow behavior occurs in the open where it can be easily
    observed and measured.









What has been learned from Tree Swallow research?
The list is long and impressive.  For instance:
  • Much pioneering work on bird reproductive behavior and mating systems
    used Tree Swallows as subjects.  A great deal of what is known about
    nest site competition, extrapair paternity, mate guarding vs. frequent
    copulation, control of copulation, role of floaters, parental investment,
    seasonal reproductive effects, nestling growth and development, and
    infanticide was discovered or confirmed by scientists working with Tree
    Swallows.  
  • Tree Swallows are the focus of a 30+ year investigation of
    interrelationships among, food supply, weather factors, and reproductive
    success.  
  • The complexities of begging by songbird nestlings and responses of
    parents are being studied using cameras and recording equipment within
    swallow boxes.
  • The very extensive banding records for this species have allowed study of
    dispersal of adults and juveniles over large geographical areas.
  • Thousands of North American Tree Swallow nest records stretching over
    40 years have documented a significant advance in laying date, which has
    been cited as evidence for global warming.
  • Clutch size and brood size have been manipulated in many ways to
    investigate various aspects of reproductive performance.
  • Adult Tree Swallows have been temporarily handicapped to examine their
    ability to forage for their young.
  • Box nesting in Tree Swallows has made it easy to explore effects of
    ectoparasite loads on nestling growth and survival.
  • Tree Swallows have had their diets supplemented, and have been bled,
    inoculated, and irradiated in various experiments investigating their
    biochemical and physiological responses.
  • Recently it's become a standard procedure for government agencies and
    businesses to analyse Tree Swallow body tissues to monitor extent and
    effect of the spread of man-made contaminants from aquatic to
    terrestrial ecosystems.
  • Tree Swallows have recently been used in the study of senescence on
    reproductive success, and their chromosomes' telomeres have been
    studied for their role in aging and lifespan in birds.
  • An ambitious and unique project, Golondrinas de las Americas, has been
    launched whose purpose is to compare the reproductive biology of all
    nine members of genus Tachycineta.  Dozens of study sites have been
    established throughout the new world, from Alaska to Tierra del Fuego
    (see map), and data has begun to be reported in the scientific journals.  
    Check out their web site to get a sense of the scope of this project.

Bet you didn't realize all this stuff was going on!  Almost nobody besides
professional ornithologists does.  Certainly the average birder has no clue that
in the exploration of songbird biology, ecology and behavior of songbirds the
contribution of Tree Swallows is unparalleled.

If you want to check out some particular journal articles you can refer to our
Tree Swallow Research Bibliography.  Nearly all the titles listed used Tree
Swallows as either the primary research subject or as a comparison species.  
These articles aren't exactly "light reading" and you're not going to find them in
your public library.  You may be able to find some of the more recent ones
online, but for most you'll need to visit college libraries.

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Sampling a nestling's blood.  Photo courtesy of Golondrinas de las Americas