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

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 (that
live on their outer body surfaces) and endoparasites (that enter the host
birds' bodies and live within their tissues or organs).  It's a fact of life.  
(Below: a bird flea magnified many times).










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 very 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 moving specks.  
    Don't look too closely at little specks - they can jump, on you!
  • All the little pepper-like specks on mud rim of the Barn Swallow nest
    below are bird mites.  This nest was loaded.











How did ectoparasites get into the nests?
  • Adult fleas, mites, and lice arrive on adult swallows.
  • 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?
  • Tree Swallow ectoparasites haven't been proven to kill nestlings
    directly, but high blowfly loads can cause anemia, which may slow
    nestling growth and make them more susceptible to starvation.
  • Heavy ectoparasite infestations can also depress nestling immune
    systems, harming their ability to resist illness and environmental stress.
  • In addition ectoparasites have the potential to transmit infectious
    diseases to their hosts.
  • 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
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