Birding: Post-breeding dispersal behavior
While summer officially started just a few weeks ago, some wild bird species are already starting to wrap up breeding activity. During breeding season, nesting birds establish a territory where they will find food to rear their young.
Between the process of nest building, incubating eggs, and rearing young, the adults are really pretty much tied-down to this full time occupation, and stay within their territory. However, once they become empty-nesters, they are no longer bound down by their parental duties and are now free to move about the countryside. Sounds kind of familiar, doesn’t it?
Not only will the parents begin to wander further and further away from the nest site, but so will their fledglings as they gain more experience and confidence. This behavior of birds branching out and away from their previously established territory for purposes of rearing young is referred to as post-breeding dispersal.
This behavior explains why all of a sudden you start seeing birds in your yard again that you saw during spring migration. Species such as orioles, grosbeaks and tanagers that you initially saw in April and May will start frequenting your feeders again, along with their young.
If you have taken down your oriole feeders, it would be a good idea to put them back out for another six or seven weeks. If the activity at your seed feeders has been a little slow over the last month or two, you will soon start to notice an increase in activity as the parents and their young start hitting the feeders.
This period of time can be a bit challenging for new birders, as the juveniles start showing up at their feeders. In many species, male and female juveniles have not yet obtained their adult plumage, so it can be tricky to identify some of these new arrivals.
One suggestion for identification is to observe who these “new,” hard-to-identify birds are hanging out with. You can often identify a bird by others with whom it is associating. When you see juveniles that have similar size, shape, behavior, food preferences and beak structure — but different plumage — you can frequently figure out who they are by looking at the adult males and females who have more defined, distinctive plumage.
Believe it or not, some species are already on the move, migrating south from their summer breeding range. An example of this is the rufous hummingbird. Each year I start receiving reports of rufous hummingbird sightings either the last week of June or the first week of July.
It is remarkable to consider the distance this species covers. It breeds as far north as southern Alaska and winters as far south as Central America. Males typically arrive about a month before females. Shortly after the females arrive, then the juveniles start to show up.
Right now is a great time to start putting up additional hummingbird feeders in anticipation of the rufous showing up. As you have probably experienced in previous years, any semblance of peace at your feeders will be promptly shattered with the arrival of a rufous hummingbird.
Male rufous hummingbirds are very territorial and very aggressive. When they find a feeder, they quickly lay claim to it and strive, to the best of their ability, to drive off and chase away every hummingbird they see. Adding additional hummingbird feeders will make it more possible for the other hummingbirds in your yard to sneak a quick drink while the rufous is off chasing other hummingbirds.
A quick reminder — if you are not yet providing a source of water in your yard, I would strongly encourage you to do so, as our monsoons are delayed in starting and the weather continues to be very hot and dry.
Until next week, Happy Birding!
Eric Moore is the owner of Jay’s Bird Barn, with three locations in northern Arizona – Prescott, Sedona and Flagstaff. Eric has been an avid birder for over 50 years. If you have questions about wild birds that you would like discussed in future articles, email him at email@example.com.