Summer rains will positively impact winter bird populations

Visual reference

Karen Shaw/Courtesy

A pair of long-billed dowitchers at Willow Lake in Prescott, Arizona.

Eric Moore

Eric Moore is the owner of The Lookout, formerly known as Jay’s Bird Barn in Prescott, Arizona. 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:

Over the last few weeks, our abundant summer monsoon rains have turned the Arizona Central Highlands green! An amazing transformation has taken place since the monsoon rains kicked in.

My wife and I were walking on the Peavine Trail just a few days ago, and I was marveling at the "weeds." I commented that there will be a lot of natural food available to our wild birds this winter. This is in stark contrast to last winter, when there were very few natural food sources available to our wild birds.

Last summer I recorded only about two inches of rain at our home. It was a disappointing monsoon season. Most winters, the Prescott area has a good influx of seed-eating bird species such as dark-eyed juncos, pine siskins and, in some years, Cassin's finches.

Last winter the number of dark-eyed juncos was way down, and I never saw a single pine siskin or Cassin's finch. It was obvious that the number of seed-eaters in the Prescott area was down due to the poor monsoon season.

Migratory birds are directly affected by weather - even weather events that occur months before the birds migrate. The breeding range for many of our winter birds is far to the north of us. I suspect they have no way of knowing whether Prescott experienced abundant summer rains or not - until months later, when they arrive in our area.

If they find there is sufficient food to sustain them through the winter months, chances are they'll stay. However, if they encounter a situation like last fall, when there wasn't a lot of food, they move on.

Migratory behavior is very dynamic. Birds naturally adjust to changes in food availability. In the past I've written about "irruptive" years where birds occur outside of their "normal" winter range. This happens when food populations crash in their regular winter range.

Migration (and survival) is really all about food. Birds migrate, not because they can't withstand cold temperatures, but because their primary food source is no longer available to them where they spent their summer.

For example, think of insect-eating birds that summer in the mountains of Montana or Wyoming. Food is plentiful during long summer days. However, as the days get shorter and freezing temperatures become the norm, what happens to the insect population? It goes away. Insect-eating birds migrate to ensure they have access to a reliable food source. Therefore, most neo-tropical bird species migrate to Mexico, Central America or even South America. Insects are abundant there while here in North America we endure the long, cold winter days.

Seed-eating bird species can stay in colder climates, such as Prescott, if we have abundant summer rains. Seeds produced in summer provide a constant food source sufficient to sustain birds until the following spring.

A basic understanding of weather can help to predict future migratory activity. What happens in July and August directly impacts birds in November, December, and January.

One thing that has surprised me recently is the high demand for suet by our summer birds. Historically, suet has been considered more of a winter food source, but more than ever our summer birds are seeking out suet feeders.

Ironically, the supply of suet has been very unpredictable. We continue to experience periods where suet products are out of stock and on back order. We normally carry about ten different suet flavors, but recently we got down to just one suet flavor as we couldn't get the product. Finally, this past week, we received a long-awaited suet order, and we have plenty of product to meet the demand of your suet-loving birds.

Until next week, Happy Birding!