What's different about banding nestling Tree Swallows?
It's much simpler than banding adults. All the bander does is affix the band and
record the bird's species, age, and band number, plus the date and location.
However, there are some very important timing and handling rules.
For your own records you can use our Nestling Banding Record.
You record each nestling's:
- Box number.
- Date of banding.
- Age in days after hatching.
- Band number.
It's impossible to determine nestling sex by plumage or other external appearance.
When are nestlings banded?
There is a very short window of time for banding nestlings, either day 11 or
day 12 after hatching. (This is one more reason for keeping a Control Sheet that
tracks nestling age at each box). Your bander must resist the temptation to band
nestlings outside the window.
Warning! Before day 11 nestling legs are usually too swelled with fatty tissue.
Applying a band could squeeze and damage the leg.
Warning! Nestlings older than day 12 should not be handled for any reason,
including banding! Doing so could cause them to jump from their nest before they
could fly strongly, and swallows that fledge prematurely usually die.
Take a close look at the 12 day nestling's wing, below. Notice how the flight
feathers have partly erupted from their sheaths, so they look like little paintbrushes.
If you find nestlings in a box with flight feathers more erupted than those in
this example, leave them alone! Handling them for any reason, even banding,
risks premature fledging and the death of the birds.
Warning! Adult Tree Swallows must never be allowed to see their nest
emptied of young or they may desert! Either band nestlings next to the box, which
prevents adults from entering, or if you must move nestlings away from the box, take
half the brood at a time, so the nest is never empty.
Will your young swallows return to your project as adults to nest?
- Don't expect many nestlings to return.
- While 30-60% of adult nesters will be back, banding studies show nestling
returns average less than 10%, often much less.
Why is there such a difference in return rates of adults and nestlings?
- Mortality of young, inexperienced swallows is high during their first autumn and
winter of life.
- One study of Tree Swallow demographics estimated only 20% of young
swallows survived to their first nesting season.
- Young Tree Swallows in their first nesting season also tend to migrate north
later than older adults. If they do come back to where they were raised they
are apt to find nest sites already claimed and defended by older swallows.
- The options for younger birds are to try to take a nest site away from more
experienced swallows; float in the area and wait for a vacancy that may never
occur; or prospect for nest sites elsewhere.
The combination of high first-year death rates and shortage of nest sites means you
won't find many of your nestlings back at your projects as adults. However, have
them banded anyway, if you can. They may be reported nesting elsewhere, and this
can help scientists studying Tree Swallow dispersal.
Learn About Birds at Tree Swallow Nest Box Projects