Several colleagues teased me this week about my sabbatical being over now that the semester has ended. Fortunately though, I can continue my research activities until August. I started this blog to chronical my sabbatical and I had the intention of writing a post about once a week. I maintained that frequency through March, but the time between posts has gotten longer as my personal and professional lives have gotten busier. On the personal front, I have just become a first-time homeowner! I can’t imagine going through this process while teaching full time, so I am thankful that my sabbatical has coincided with this big life step. I am now moved in, and I know where most of my stuff is, even if it is still mostly in boxes.
On the professional front, my research is in full swing. The woodpeckers I am studying at Powdermill Nature Reserve are finishing up nest construction and possibly laying eggs. My goal is to find at least 30 nests this season, and I have 5 located already. Woodpecker nests are in hollow trees. Rather, the woodpecker makes the tree hollow by digging into it, known as excavation. It takes about 3 weeks for a mated pair of woodpeckers to build a nest. Eggs are laid, and they are incubated for 7-10 days. Baby woodpeckers stay in the nest for about 3 weeks after hatching, and both parents care equally for the young.
On average, I find one nest per day. The purpose of my research is to determine the ideal habitat for woodpeckers, to see if it is different for different species, and to see if nest site selection by each species here in western Pennsylvania is different from that in other locations in the U.S. I am also interested in the spacing between nests. For example, do pairs of one species avoid another? We have seven species of woodpeckers that nest locally: Downy Woodpecker, Hairy Woodpecker, Red-bellied Woodpecker, Northern Flicker, Pileated Woodpecker, Red-headed Woodpecker, and Yellow-bellied Sapsucker. I am looking for nests of any of these species, though the last three in this list are rare and I won’t have a suitable sample size to draw conclusions about them.
A Typical Day in the Field
I will use today as an example of a normal workday. I awakened at 5:45 am to meet Biology major Josh Robinson at Powdermill at 7:00 am. Josh is volunteering his time to help me find nests and to enter them into the Geographic Information System (GIS) they have at Powdermill, which will help me run my habitat analysis.
We started hiking along the Sugar Camp Trail until we started hearing a Red-bellied Woodpecker vocalize off to the left. We left the trail and walked toward the sound until we spotted the bird. Woodpeckers are always so busy creeping along tree trunks and flying from branch to branch as they use their long beaks to find insects between flakes of bark and leaf buds. We kept the bird in view for a couple minutes, but then it flew to a tree far in the distance. I decided that trying to find it again would be an unsuccessful strategy, so we backtracked to the trail through a particularly muddy section of forest. Josh got mud all the way up to his pant leg. I asked if his feet were still dry and he said yes. That was good, because I have found that three hours of walking in wet boots is no fun at all!
Josh and I follow these rules developed during my 20 years of nest searching:
Walk a few paces and then stop to listen.
If you hear pecking sounds, go find the bird making them (but be aware that water gurgling in a stream and branches scraping in the breeze can misleadingly sound like a woodpecker).
If you hear woodpecker vocalizations, go find the bird if it seems close (100 yards); otherwise, ignore them because the bird will probably move before you find it.
Sometimes while listening, you will see a woodpecker flying between trees. Once in view, follow it with binoculars for as long as you can. It may lead you to its nest.
Always approach a woodpecker (or possible woodpecker location) with the sun behind your back. This way, you can see the bird clearly while the bird cannot see you as well.
If you see a tree trunk with fungus or some kind of injury, that’s a good place for a woodpecker to build a nest. Use your binoculars to look for nest holes. If the hole is of the proper diameter and shape, and the hole appears newly excavated, just watch it for a few minutes to see if a woodpecker arrives or departs from inside the tree.
If you don’t hear or see any woodpeckers but instead see some other interesting bird, take a look through your binoculars and enjoy the moment. Likewise, appreciate the wildflowers and plants you are walking through. And always look for salamanders and snakes underfoot, owls looking out from hollow trees, and the occasional porcupine, raccoon, or bear cub nestled between tree trunks.
Limit nest searches to 3 hours in the morning. After 3 hours, you get bored and dull-witted.
By 8:00am Josh and I are watching another Red-bellied Woodpecker as she probes underneath the flaky bark of hickory trees. A Downy Woodpecker appears, and (strangely) chases the Red-bellied Woodpecker from her perch. At this moment I had to decide what to do: should we follow the Red-belly, or should we begin watching the Downy Woodpecker? It’s pretty much impossible to follow more than one bird at a time…though as Josh gets more experience, I can ask him to follow one bird while I follow the other. Today, though, I wanted to follow the Downy. Downy Woodpecker nests are more difficult to find than Red-bellied Woodpeckers because the Downies have smaller nests that can be located higher off the ground.
My strategy turned out successful. The Downy Woodpecker flew to a broken and dead trunk of a live maple tree for a moment, and then flew again to an adjacent tree as a second Downy Woodpecker showed up. Was this second bird a male or female? It couldn’t tell, since I never saw the back of the head where males have a patch of red whereas females do not. The two birds were calling to one another, and again, I couldn’t tell whether this was an aggressive interaction (such as between two females) or an example of courtship (such as between a male and a female). In nature, the two are often very similar in terms of behaviors displayed.
My focus turned away from the loudly interacting birds as I examined the dead tree trunk more closely. It fit the pattern of where woodpeckers build nests: dead wood in a live tree, 25 feet off the ground (see
photo of a nest I found in a previous year). I saw a small hole in the dead trunk that looked like it was the start of a nest hole, but it wasn’t big enough for a woodpecker to enter. With the two Downies in the background, I walked a little ways around the tree to get a better view. Aha! There were two, more complete holes in that same trunk that I didn’t see before. I remarked to Josh, “if this ends up being a nest, it will be the lower hole because it won’t leak as much in rainy weather.”
Almost immediately, a Downy Woodpecker flew to the lower hole and looked in. The second Downy followed and perched on the same tree. Then the two got into a claw-to-claw midair flutter flight that often precedes copulation. A couple branches obscured my complete view, so I don’t know if the two ever got into the proper position for copulation, but I didn’t need to see it. My own published work, as well as those who have published before me, indicates that Downy Woodpeckers always copulate near the nest (let’s say within 30 yards or so). That hole in the dead trunk now appeared to be an even stronger candidate for being a nest because of the behavior shown by these two courting birds.
Eventually, both woodpeckers went to the hole’s entrance, but neither entered the cavity. I think Josh and I were too close, even though we had backed up to give them some room. I will have to return to this nest hole again this week to confirm that it is indeed a nest.
In the meantime, I took some written notes and then got out some orange surveyor’s flagging and a permanent pen. I wrote “DOWO nest 5-6-15 Kellam” on the flagging and tied it to a bush next to the nest tree. I never flag the actual tree for fear of causing a disturbance and/or pointing out the nest to possible predators that can read my handwriting (those raccoons are smarter than we think). I also used a GPS receiver to record the map coordinates of the nest for ease in finding the location again as well as analyzing the spacing between woodpecker nests.
By the time we were done at this prospective nest site, it was 8:30am. Josh and I continued our searching and found a second Downy Woodpecker nest about an hour later. This was found in the same manner as before, immediately after we witnessed a 14-second copulation between male and female. Josh was impressed, but I failed to tell him how unusual it was to see a copulation. Woodpeckers only copulate a few times per year, deep in the woods, for only seconds at a time. When was the last time you saw one occur?
With a second nest discovered, Josh and I high-fived and continued to search for more through 10:15am. Walking 2.6 miles through 11.8 acres of forest (my GPS receiver records this), we saw several Red-bellied Woodpeckers, several Downies, and a pair of Pileated Woodpeckers, all of whose nests we will have to find another day. We heard a Northern Flicker, too. Meanwhile the woods were alive with the flittering spectacle of Yellow-throated Vireos, Scarlet Tanagers, Baltimore Orioles, Blue Jays, Tufted Titmice, White-breasted Nuthatches, Yellow-rumped Warblers, Kentucky Warblers, Eastern Towhees, and numerous other birds including teasing silhouettes that never gave us their names.