At the Project:
Most nestlings have fledged.  A few late nests, or renests, may still be active.  It's
time to check inside boxes whose nestlings you know have left for certain.  

Bring disposable gloves and a trash bag if you plan to remove old nests.   Also, you
might want to collect a few nests for ectoparasite examination.  If so, take along
some large zip-lock bags.  Although this ranks high on the "ick" scale, it's important to
realize that all songbirds have both ectoparasites (little critters that live on a bird's
outer body surfaces) and endoparasites (little critters that enter a host bird's body
and live in or on the bird's tissues or organs).  It's a fact of life.  (Below: a bird flea
greatly magnified).










Concepts:
Resume checking boxes where young have fledged:
  • Be absolutely certain no live young remain in the box before you go near it!!  
    Be positive feeding has stopped.  If it's day 20 or later, with no sign adults are
    feeding nestlings, take a peek.
  • Open the box a crack, making sure there are no living young inside.
  • Determine number of nestlings fledged by subtracting the number of dead in
    the box, if any, from the number counted alive at day 12 (or your closest count
    day before day 12).

What is the nest like inside now?
  • Wear disposable gloves handling old nests.
  • Late-stage nests are apt to be fouled with feces and smelly.
  • Dead nestlings, if any, add to the unsanitary conditions.














Collect nests for ectoparasite examination:
  • Stand upwind to avoid blowing nest debris.
  • Remove the nest.  Most of it should come out in one or two pieces.
  • If the nest has dead nestlings remove the nest from the box but don't use it
    for ectoparasite examination.
  • Put each nest to be examined in a zip-lock bag and seal tightly.
















  • Take nests elsewhere for examination.  Not inside your house!!!
  • Put a weighted sheet of newspaper or cardboard down to give background
    visibility and to make clean-up easier.
  • Wearing gloves remove a nest from its bag, put it on the paper, and pull it
    apart.
  • Check out the little crawly things!
  • If you don't want them crawly, microwave the bagged nest briefly.  (But they'll
    be harder to see if they aren't moving).

What ectoparasites should you find?
  • Most Tree Swallow nests are loaded with bird fleas, both larvae (the white
    curly things (below left) and adults (below right).  These fleas specialize on
    cavity-nesting birds.  They won't attack you or your pets.







  • There may be pupal cases of blood-sucking blowflies (below).







  • There may also be bird lice and mites.  Lice can be hard to find, but mites
    infestations can be heavy.  Mites look like little specks, but don't look too
    closely at little specks - they can jump, on you!
  • The tiny red specks on flange of the nestling below are blood-sucking mites.  














How did ectoparasites get into the nests?
  • Adult fleas, mites, and lice ride in on adult swallows, usually the parents.
  • Blowfly adults are attracted by nest odor.  They lay eggs in nest material.  
    Their larvae suck body fluids from nestlings.

Don't ectoparasites harm nestlings?
  • It's hard to prove that Tree Swallow ectoparasites kill nestlings directly, but
    high blowfly loads can cause anemia, which may slow nestling growth and make
    them more susceptible to starvation and hypothermia.
  • Heavy ectoparasite infestations can also depress nestling immune systems,
    harming their ability to resist illness and environmental stress, leaving them in
    poorer condition and less apt to survive after fledging.
  • In addition ectoparasites have the potential to transmit infectious diseases to
    their hosts.
  • In extreme cases the presence of ectoparasites can have disastrous effects.  
    The swarm of mites (see below left, around an entrance hole) was believed to
    have had led to parental desertion and subsequent deaths of the six nestlings
    within the box.  (Photos by Sal the Butterfly Hunter).













  • Some endoparasites and subcutaneous parasites can damage tissue in ways
    that ultimately cause death.  The unfortunate nestlings below were host to
    subcutaneous blowfly larvae that penetrated tissues in their heads and
    destroyed their eyes.  One can be seen exiting the face of the nestling to at
    right.  (Pictures by Dick Stauffer).  







  • For an excellent discussion of life cycles and effects of both ectoparasitic and
    subcutaneous blowflys on nestling birds click here.
  • To access another web site page presenting a comprehensive summary of
    ectoparasites infesting Purple Martins click here.  Martins are another species
    of cavity-nesting swallow, and are affected by many of the same parasites as
    Tree Swallows.  

Are all the invertebrates in old nests ectoparasites?
  • No, some critters in nests are harmless or actually helpful.
  • Some eat bird feces, nest material, or cast off feather sheaths and skin
    fragments.
  • Dead nestlings attract insect scavengers, including carrion beetles.

Questions for the next Topic:  Juveniles.
  • Can you tell juvenile Tree Swallows from adults?
  • What are juveniles doing?  What behaviors do they show?









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Ectoparasites
Learn About Birds at Tree Swallow Nest Box Projects