At the Project:
Books, videos, CDs, and the web all help if you want to learn about wild birds, but at
some point you need to get out and see your subjects first hand.  And now is your
chance.  Your first Tree Swallows have arrived!  Photo below by Danny Bales.

It's early spring.  Temperatures may sometimes drop below freezing, but in spite of
this Tree Swallows have begun migrating north, and as they reached their breeding
range and spread out some have discovered the nest boxes you put up for them.  

So now it's time to start getting to know your birds.

Put on warm clothes, boots, hat and gloves, since there may still be snow on the
ground (see below).  Bring an old folding chair, (but if the ground is soft you'll end up
standing).  Binocs may help if this is your first real meeting with Tree Swallows.  You
probably won't need them later on.

Go in the morning when Tree Swallows are most apt to visit and explore potential nest
sites.  Early season afternoons they usually spend feeding elsewhere.

Sit where you can watch boxes with swallow activity.  Their behavior centers on the
boxes because these boxes and their contents will be the most important things in the
swallows' lives for the next ten weeks.  Watch for awhile, then move to another box
and watch some more.  And while you observe ask yourself why in the world these
birds have arrived so early in the year.

Where do Tree Swallows spend the winter months?
  • Many Tree Swallows winter in warm parts of the southern U.S., especially in
    Florida and Louisiana.  Others winter even farther south in Mexico, Central
    America and Cuba.

What's the advantage of wintering in the south for Tree Swallows?
  • Tree Swallows' primary food is flying insects.
  • Flying insects are usually unavailable during northern winters, so Tree Swallows
    concentrate at buggy southern wetlands in winter, sometimes in huge flocks.  
  • Unfortunately, many wetlands on the wintering grounds have been lost or
    degraded by development, agriculture and aquaculture.
  • Tree Swallows also eat certain types of berries on their southward migration
    and especially in winter, and these particular berries aren't found at most of the
    swallows' northern nesting grounds.

When will Tree Swallows begin to arrive where you live?
  • This depends on several things, including how far you are from the swallows'
    wintering grounds, the swallows' migration path, the general climate in your
    area, and the weather conditions you are experiencing this particular year.
  • You can usually get regional arrival information by asking birding experts in
    your area, or you can use the eBird website, as follows:
  • On the eBird website choose the Explore page.
  • On the Explore page select Bar Graphs, which takes you to the Choose
    Locations page.
  • On the Choose Locations page, identify your Region (country and state or
    province), and then your Subregion (choose one or more counties).
  • Next, a Bird Observations page will appear.  Scroll down the species list and
    select Tree Swallow.
  • The Tree Swallow observations page will appear, with graphs showing its
    occurrence and frequency at the location you've chosen.  
  • There are two partial examples below.

  • The first shows that Tree Swallows begin arriving in the Danville, Virginia, area
    by Mid-March.  

  • The second reveals that this species usually doesn't arrive much before early
    May in Prince Albert, Saskatchewan.

  • If you're interested in the annual continent-wide movements of the Tree Swallow
    as a species eBird now offers an excellent "Abundance Animation" video.

Why do Tree Swallows try to return to the breeding grounds so early?  Isn't
this dangerous?  After all, the north isn't very buggy in early spring.
  • The swallows return early, risking death from starvation and hypothermia, for
    one reason, to try to get nest sites so they can have a chance to reproduce.  
    The next 80-90 days of their lives will center on nest sites and their contents.
  • Tree Swallows unlucky enough to be caught by early-spring cold weather find
    themselves in a struggle for their lives.  Photo below by Rich Rehrig.

  • Note how the desperate swallows in Colin Haigh's photo below have huddled
    together to conserve body heat.  Some have actually perched on the backs of
    others!  They have also fluffed up their feathers to trap more air underneath,
    which increases its insulation value.

  • To view a YouTube video by Ken Cheatham of migrant Tree Swallows and
    Violet-Green Swallows trying to survive an Alaskan spring cold snap by
    huddling together in piles click here.
  • Another form of huddling to conserve heat is "communal roosting," in which a
    group of birds crowds into a cavity or nest box overnight.  The feces on the
    floor below are evidence Tree Swallows used the box as a communal roost.  
    This behavior probably saves the lives of many Tree Swallows each year, but in
    spite of these efforts birds weakened by days with little heat or food may die.

  • Be warned: after cold snaps you may find dead adult Tree Swallows inside your
    boxes.  The seven barely recognizable swallows below all died in a single box.

But hopefully your swallows arrived to find good weather and aren't
struggling to survive.  If you're like us you'll be eager to see them, and if
you're new to this species now is a good time to check for these basic Tree
Swallow features:
  • Dark head and upper body, usually, but not always, iridescent blue-green.
  • Pure white throat and underbody.
  • Wings long, dark and pointed.
  • Tail short, dark and notched.
  • Head somewhat flattish with short neck.
  • Eyes dark and hard to see.
  • Bill short and small.
  • Feet small and legs very short.
  • Slender, streamlined, overall appearance.

No animal is good at everything.  There's a saying that "form follows
function".  So what do you think Tree Swallow bodies are specialized for?

How do they fly?
  • Fast or slow?
  • Agile or awkward?
  • Turn a lot or fly in straight lines?

How do they move on the ground?
  • Walk or hop?
  • Move easily or awkwardly?
  • Did you even see one on the ground?

Are Tree Swallows specialized for life in the air or on the ground?  Where do
you think they find most of their food?
  • Tree Swallows are extremely skilled, highly-maneuverable fliers that spend
    many hours in the air every day.  
  • Books often mention their tendency to glide in circles, but like all other North
    American swallows they can also soar, kite, hover, power dive, dash, or flutter
    slowly, as the situation demands.
  • Tree Swallows feed by catching flying insects in their mouths.
  • They may land on the ground to sun, get nest material, or find certain foods,
    but they usually perch above-ground.

Why do the swallows let you watch them so closely?
  • They are such good fliers they know escape from you is easy.
  • They may not view you as something dangerous at all.

Seeing Tree Swallow behavior up close lets you perfect observation skills.
Get used to asking yourself:
  • What's each behavior's purpose?  How does it help Tree Swallows survive or
    raise young?
  • What stimulates a behavior, causing it to occur?
  • Does a behavior's frequency change during the nesting season, and if so, why?
  • Do males and females behave alike or differently, and why?

Question for the next Topic:  Songbird Behavior as shown by Tree Swallows.
  • What are some characteristics of songbird behavior?

Tree Swallow Spring Return
to the Nesting Grounds
Learn About Birds at Tree Swallow Nest Box Projects