Laura Erickson's For the Birds

Monday, September 20, 2021

Hot, Peppery Bird Food

Blue Jay

On January 31 of this year, my husband Russ set a small platform feeder on the window outside my new home office. I’d switched last year from the largest room in the house to one of the smallest when my daughter and son-in-law came to live with us. I didn’t mind losing the space—I'm close to retiring so was ready to downsize my stuff anyway, and my new office is nice and cozy.  But I was sad about losing my two large windows, one facing the backyard, the other looking into the branches of one of my box elders. As it turns out, the much smaller single window I have in my new space has given me some of the nicest photos I’ve ever taken, and the feeder Russ put in has increased the photo ops enormously.  

Grandma showing Walter a chickadee

The first birds to show up at the feeder were, of course, chickadees, but I cheated—all I had to do was whistle to get them to fly in for mealworms. Red- and White-breasted Nuthatches and a Downy Woodpecker keeping track of the chickadees also quickly found the feeder. 

All was well until February 4 when a gray squirrel jumped into it from an overhang about 2 feet lower than the feeder and about four feet away horizontally, an especially tricky maneuver when the overhang was slippery with ice. But that was the only time I saw a squirrel in the feeder for a few months. By the end of April, my feeder bird list was up to 13 species.  

Evening Grosbeaks in my window feeder

But with spring, a couple of squirrels became adept at the long jump. It was irritating, but not enough for me to close down the feeder until spring migration was over. The squirrels were a small price to pay for some lovely Indigo Bunting photos.  

Indigo Bunting

When I closed down the feeder at the start of June, my nesting chickadees could still catch my eye and I’d open the window to give them mealworms. But the window feeder was otherwise left empty all summer. The few times I filled it this fall, a squirrel showed up within an hour. 

But with this year’s amazing Blue Jay migration, I really really wanted to get the window feeder going again. Neither Russ nor I could think of a single way to close off access to those squirrels. So I finally decided to try some birdseed laced with hot red peppers. 

I used to counsel caution regarding bird food formulations with peppers. It seemed like anything that could burn our mouths and be such an irritant to our eyes had to be equally bad for birds even if they lacked the taste receptors to shun it. But I recently read about the evolution of peppers. Squirrels and other mammals chew fruits, breaking and grinding up the seeds, which damages rather than helps a plant’s chances of reproduction. Birds swallow chunks of fruits whole, so most of the seeds remain intact as they pass through the avian digestive system, and birds fly to many places over the course of a day, allowing them to “plant” those seeds over a large area. The bright colors of peppers evolved specifically to attract birds, and the pepper fruits are very nutritious, keeping birds coming back. So on September 11, I bought an expensive bag of what Wild Birds Unlimited calls “Fiery Feast” and put it in the feeder. 

Chickadees were first to come, grab peanut halves, and fly off, but Blue Jays weren’t far behind. My feeder is just 22” x 9”, and it’s hard for birds to sit along the edge against the windowsill, but I’ve had as many as 12 jays crowd in to pig out. We still have a big platform feeder and a small one, both filled with regular sunflower seeds, down in the regular, squirrel-proof feeding station, and every day all week jays have been crowding into all of them as well as visiting the birdbaths and spending time in the trees. I live right under Hawk Ridge where, as of the end of the day yesterday, September 19, they’d counted 48,523 jays, and apparently a lot of them want  a lunch break as they pass over. 

A squirrel jumped in two or three times that first day, and once or twice since then, but one taste and it jumped right back out. 

Blue Jays and chickadees haven’t been the only birds to visit the feeder. So far no other songbirds have stopped at it, probably because they don’t want to contend with the jays, but I’ve had both an adult female and a young male Red-bellied Woodpecker coming a few times each day. 

Red-bellied Woodpecker Hatch-year male

If that wasn’t good enough, one female flicker showed up this weekend, giving me several fairly good photos right through the window glass—I have always seen plenty of flickers in my yard, including at my birdbaths, but this is the first one in all our years on Peabody Street to visit any of our bird feeders. So that was of course very cool.  

Northern Flicker

Even better, I’ve had at least two Pileated Woodpeckers—a male and a female—coming to the feeder. 

Both pileateds and flickers are also attracted to ants, which are laced with formic acid, but I didn’t expect either to show up for seeds laced with hot peppers. I love how after birding for 46 years, I’m still learning.

In another week or so, I’ll start mixing in more affordable fare, keeping enough of the peppery food in there to remind the squirrels to stay clear. “Fiery Feast” is expensive and the birds eating it have big appetites—they went through a $36 bag in just one week. That’s a pretty steep price to pay to keep one feeder squirrel-free, but again, after birding for 46 years, I apparently still have a lot to learn. 

Pileated Woodpecker at bird feeder

Thursday, September 2, 2021

Interesting Acorn Woodpecker Research

Acorn Woodpecker

Last year, Storey published a book of mine, The Love Lives of Birds, in which we highlighted 35 species and their different approaches to acquiring a territory and mating.

Some species—swans, cranes, crows and many jays for example—famously mate for life and stay together throughout the year, whether they migrate away from their territory or not. Some, such as albatrosses, loons, and eagles, don’t maintain a year-round bond but return to the exact same territory each spring, ending up with the same mate year after year as long as that mate also returns.  

Many songbirds commit to a mate for a single season, but the following year are as likely to settle in with another bird as that former mate. Some, such as House Wrens, stick with a mate to raise one batch of babies but then both birds very often find another mate if they want to produce subsequent broods that same season. Some forge a temporary bond for just part of the nesting cycle. For example, Mallard drakes stay with hens after courtship only through the time the females build nests and lay their large clutches of one egg a day for a couple of weeks. When a female starts incubating those eggs and loses interest in sex, her mate is out of there. Grouse, turkeys, woodcocks, and hummingbirds separate the act of mating from nesting and raising young; males mate with as many females as they can attract, forming no discernible pair bond with any of them.

There seem to be almost as many mating and territory strategies as there are bird species, and so covering just 35 species barely scratched the surface—that’s less than 5 percent of the more than 700 species that breed in North America, and less than a third of one percent of the roughly 10,000 bird species in the world. I could have written huge chapters about a lot of other birds, and particularly felt bad leaving out one fascinating species, the Acorn Woodpecker. Several researchers I know, including ones I worked with at the Cornell Lab of Ornithology, focused years of research on this amazing bird.

Acorn Woodpecker

I saw my first on Mt. Lemmon in Arizona on 7 April 1982 (no photos), and even before I got a glimpse of the birds themselves, I was gobsmacked by what they had done—one entire side of a log cabin where we stayed was riddled with hundreds, maybe thousands, of holes, virtually every one stuffed with a single acorn. I knew from my reading that Acorn Woodpeckers made these granaries, but had no idea they could be so huge, storing so very many acorns.

Acorn Woodpecker tree

The granaries are constructed by family groups of a dozen or more individuals, who store the acorns communally, and cooperatively raise the young. Living up to their name and all the work involved in building, stuffing, and maintaining those granaries, Acorn Woodpeckers do eat a lot of acorns, especially in winter, but overall, their diet is surprisingly varied. They glean and dig out insects from trees as other woodpeckers do; catch flying insects on the wing; dig out sap wells to feed like sapsuckers; eat flower nectar; take small lizards, baby birds, and eggs; and eat some fruit and seeds. They also visit feeders for seeds, suet, and hummingbird nectar.

Acorn Woodpecker

We know from decades of long-term studies of marked birds that Acorn Woodpeckers have an unusual mating system called opportunistic polygynandry. Within a group, 1–8 males compete for matings with 1–4 females who all lay their eggs in the same nest cavity. The males and females share incubating duties. In addition to these core breeding individuals can be 1–10 non-breeding “helpers” that assist the breeders in feeding nestlings. As with many other birds, such as crows and Florida Scrub-Jays, in which one or more individuals help nesting pairs raise their young, helpers at Acorn Woodpecker nests tend to be offspring fledged by the group in prior years. Non-breeding Acorn Woodpecker helpers may be as old as 5 years old. Cohorts of males and cohorts of females tend to be related to one another—usually siblings—but the two cohorts in a flock are not related to each other. Yep—that’s one heck of a unique mating system.

Acorn Woodpecker

For many decades, long-term research projects studying birds like the Acorn Woodpecker involved marking individual banded birds with uniquely colored leg bands or wing tags and spending many hours in the field observing their activities. New high-tech equipment, from RFID tags to satellite transmitters of increasingly tinier sizes, are allowing researchers to get data on many more individual birds 24/7, even when no one on the research team is anywhere near. Newer, less expensive ways of testing DNA have taken the guesswork out of determining paternity and, in the case of Acorn Woodpeckers and other species in which multiple females share a nest, maternity as well. Now, thanks to two projects led by Sahas Barve of the Smithsonian National Museum of Natural History, one published last year in Current Biology and another published last month in Proceedings of the Society B, we know a lot more about the Acorn Woodpeckers’ unique mating system, and also about how territorial battles between flocks attract non-participating Acorn Woodpecker as spectators. 

It's long been assumed that for species in which the male and female parents both make fairly equal contributions to raising their young, monogamous pairs that defend a territory, not sharing resources with neighboring birds, are more successful than polygamous species in which males share their territory with other males. But the 2021 Smithsonian project found that that those male Acorn Woodpeckers that breed polygamously in duos or trios of males each fathered more offspring than males breeding alone with a single female. Females didn’t get the same benefit. Co-breeding duos of females produced the same number of offspring as the females that coupled up, but female trios left behind fewer offspring than either group.  

Acorn Woodpecker

Acorn Woodpeckers may provide an exceptional example of cooperation in their mate- and nest-sharing, but they have a violent, bloodthirsty, side, too, as research published last year by the same team led by Barve proved. A nesting group’s territory averages 15 acres with one or more granaries. Ownership is stable until there’s a death in the flock. If a breeding female dies, for example, coalitions of non-breeding “helper” females from other flocks will battle with the breeding and non-breeding females from the other flock, trying to take over from the homeowning females. Invading females may return day after day from their own territory. The term “battle” isn’t an exaggeration. Barve told a New York Times reporter, “We’ve seen birds with eyes gouged out, wings broken, bloody feathers and birds that fell to the ground fighting each other.”  

Thanks to the RFID chips which tirelessly record birds every time they appear near the RFID reader, we know that some tagged individuals fought for 10 hours at a stretch for four consecutive days. Although a great many birds in the vicinity have been tagged, one long-lasting battle ended up being won by an unmarked coalition of females.  

No one knows exactly how Acorn Woodpeckers get the word out, but soon after a death occurs, invaders arrive, and within an hour after the first blows, birds from other flocks arrive to watch. They may travel more than 2 miles and spend a full hour watching these battles. Spending so much time attending these battles just to observe must have some value—these birds would normally be spending those hours feeding young, searching out more acorns for their granaries, and defending their own territories to prevent the theft of acorns. Dr. Barve told the New York Times that studying other Acorn Woodpeckers must give them some sort of advantage. “They must immediately see all the big sibling coalitions in the area, gauge their body conditions and the quality of the territory they’re fighting over,” he said.  

Working out the evolutionary advantages for watching other birds fighting is tricky, and we can’t help but wonder whether the impulse for Acorn Woodpeckers to observe other flocks engaging in these fights is comparable to the impulse of people to spend a significant amount of time observing football, World Wide Wrestling matches, or the crazier reality TV shows. But I guess it’s nice to know that there's a counterpart to spectator sports in the world of birds. Maybe there really is nothing new under the sun.  

Acorn Woodpecker