Tackling Tricky Codes Part 2: The Probables...

By Ashley Peele 18 Apr 2017

Northern Flicker dispute (Betty Sue Cohen)

For our second installment of this series, we’ll be focusing on tricky Probable codes.  Much of atlasing effort is focused on trying to upgrade species to this category or higher.  Fortunately, behaviors suitable for the Probable breeding category are fairly common to observe, but it is important to make sure we’re interpreting the use of these correctly.  Let’s begin with a code that is common early in the breeding season…

Pair in Suitable Habitat – P

In many ways, this is a fairly straightforward code.  The hard and fast rule for applying it is that a pair of birds should only be coded as P, if the male and female of the species are identifiable by plumage. 

If the two sexes have identical plumage, then this code should not be used.  There are many species of birds that this applies to, so we won’t list all here.  Just remember, identical sexes = no P code.

Note! Sometimes the behavior of a pair of birds (e.g. Chipping Sparrows) suggests that they are a pair.  Perhaps you note one adult bird feeding another or what appears to be an adult bird begging for food.  While this suggests the two birds area  pair, another breeding is actually more appropriate here, C – Courtship Behavior or Copulation.

Wood Duck pair w/ male on left and female on right (Photo by Bob Schamerhorn)

Angry Birds – A vs. T

Several breeding codes can be applied to agitated or aggressive behavior by birds.  In this article, we’ll focus on the two relevant Probable codes for angry birds…

A – Agitated Behavior.  If a bird gives angry chip notes (aka scolding), often flying or walking repetitively through the same area, then the A code should be used.  Birds will often raise their head feathers and body feathers, as further signs of agitation.  Picture a Mockingbird scolding you from the top of a bush or a chickadee hollering from a limb above you.

It is important to note that pishing negates this code, because you cannot know if the bird’s agitation is caused by your behavior or the presence of a nest and/or young nearby.  Try to keep your human behavior out of the equation by avoiding pishing, when making breeding observations.

T – Territorial Defense.  This code covers several common behaviors that atlas volunteers are likely to observe in the field…

  • Chasing and scolding individuals of the same species (intraspecific aggression) or a different species (interspecific defense)

Great Blue Heron competition (Betty Sue Cohen)

These codes are similar and some situations will arise where either could be used.  In such cases, don’t fret over which to apply.  Since they are both in the same category, this isn’t a big issue. 

The Probable Nesters… B – Repeat Visits or Nest Building. 

Cavity-nesting species, particularly woodpeckers, excavate cavities for roosting, as well as nesting.  In such cases, noticing cavity excavation or repeat visits to a particular hole is not a confirmation of breeding, because the bird may not breed there.  For example, a male Red-bellied Woodpecker will excavate a cavity to attempt to attract a mate.  If no female likes his choice, he’ll move on to a new location.  Downy Woodpecker pairs often excavate multiple cavities before settling on a nest site.  Given that we cannot assume breeding intent for every cavity excavation we see, the probable B code is used to document these behaviors in species such as woodpeckers.

Additionally, wren species build multiple nests known as ‘dummy’ nests.  The males do this to attract females to their territory.  If successful, the female will occupy one of these nests, but their presence does not guarantee that a mated pair are present.  For this reason, we also use this Probable nest-building code for wren species.

To wrap up, we realize that it can be frustrating to stick to all of these rules.  You may see behaviors that convince you a species is attempting to breed, but that doesn’t fit into any of the codes very well.  If this occurs, shoot your state or regional coordinator an email.  We may accept an unusual code-species combination, if you provide notes to explain your observation.  Generally, however, we ask folks to adhere to these rules, which ensure consistency amongst our many volunteers, as well as amongst the many states conducting breeding bird atlases.

We’ll pick up our next article with tricky codes of the Confirmed category.  Remember the online resources available via the Atlas website at www.vabba2.org.  If you can’t find answers to your question in our handbook or other online materials, just ask!

~Ashley Peele, VABBA2 State Coordinator