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Encounters of Many Kinds

Happy New Year from all of us on the red-headed woodpecker project! We're happy to report that we had a productive year and we're already looking forward to getting back out in the field this spring. One of the things we've been working hard on over the last 18 months is fine-tuning a trail camera project aimed at better understanding red-headed woodpecker nesting behavior. Motion-triggered cameras were set up outside a sample of red-headed woodpecker cavities and we have now amassed thousands of videos, which will be viewable through a project website on Zooniverse in the coming months. Through our Woodpecker Cavity Cam project we also hope to learn more about the community of species that use and compete for the cavities that red-headed woodpeckers create for nesting and roosting.

Once the project is live, you'll be able to assist us in collecting data from these videos, so stay tuned! In the meantime, we wanted to share some of the interesting interactions the cameras have captured over the last year. Vacated red-headed woodpecker cavities appear to become prime real estate for year-round residents and birds dispersing and migrating during the fall. We have enjoyed seeing the many different kinds of interactions happening at these cavities and we hope you do too!

It probably comes as no surprise that many different squirrel species are regular, year-round visitors of these cavities. Sometimes they are in and out in a flash, and other times they stay a few days. Sometimes they throw other animals out of cavities and other times they are themselves thrown out. What is perhaps most surprising is the incredible pace at which "ownership" or use of these cavities changes in a 24-hour period. It appears much more dynamic than any of us had anticipated and it's been exciting to begin to document.

The video above shows an encounter between a fox squirrel and a flying squirrel, the latter of which appears to be in "possession" of the cavity. The flying squirrel may have heard the loud noises of the fox squirrel climbing up the tree, watching from above, seemingly without fear, despite the fox squirrel's size. The two squirrel's faces come within inches of one another and the fox squirrel immediately backs off from the encounter. It's almost too fast to catch in the video—see below for a photo.

Flying squirrels appear to be quite fierce, despite their small size. The photo below shows a standoff between a flying squirrel and a white-breasted nuthatch. Is this the same squirrel from the video above (captured two weeks prior in the same cavity)?

The next video shows a fox squirrel chasing a hairy woodpecker out of its roost cavity. The woodpecker had gone into the roost some minutes before, but emerged halfway out of the cavity, perhaps because it heard the fox squirrel climbing up the tree. The squirrel appears and lunges at the woodpecker, who then flies out of the picture giving an alarm call. The second video shows the woodpecker returning to the cavity, about a minute later, still alarm calling, with no squirrel present. The animals roosting in these cavities appear to go through encounters like this constantly almost every night. Serious deep sleep, as we consider it, is not a possibility for these animals.

The next video starts with a tree frog sitting in the cavity entrance, and a flying squirrel in the camera frame. The squirrel jumps onto the tree and circles around behind it to a branch. The frog may have felt the vibrations from the squirrel's movement and jumping, as it quickly moves out of the cavity hole as the squirrel appears and goes into the cavity. The frog moves to a spot a few inches down the tree and takes a position, perhaps to wait for an unlucky insect to fly by.

In the next video, we see a hairy woodpecker rebuffing an attack from a flying squirrel. The woodpecker was inside the cavity and appears to counter the attack with its beak. It very quickly throws the squirrel out into the air and off the tree. The woodpecker then clicks its beak repeatedly until the end of the video. Is the beak clicking an agitated warning that it is still present and will defend further attacks? Other videos have captured a similar behavior in Red-headed Woodpeckers when squirrels and mice approach their cavities.

The interaction between the hairy woodpecker and flying squirrel happens quickly. We've pulled some photos from the encounter (below) so you can see it in detail.

In another encounter, a flying squirrel is able to maneuver inside a cavity and throw out the hairy woodpecker that had been roosting there.

This exchange is also lighting fast—see below for some photos that show the encounter in more detail. The camera did not capture either of the two at the cavity again that night after this interaction.

Interactions at these cavities are not always so intense, as evidenced by the next video of a red-bellied woodpecker investigating a cavity and the bark above it before a pileated woodpecker can be heard in the background. The pileated woodpecker then appears and the red-bellied woodpecker moves to the other side of the tree before flying away, returning once the pileated woodpecker leaves (if you turn your audio up you can hear the red-bellied woodpecker calling in the background, perhaps out of frustration). Can you find the red-bellied woodpecker when it returns at the end of the video?

A pattern we have noticed in many of these videos is that a woodpecker's presence at a cavity seems to attract other woodpeckers. Sometimes a sequence through the videos shows a hairy woodpecker, then a red-bellied woodpecker, then a northern flicker, or a pileated woodpecker, all within seconds or minutes of each other. A white-breasted nuthatch or a downy woodpecker might also be mixed in. Each of them looks around and inside the cavity, gives a few pecks, sometimes goes into the cavity for a minute or more, and then flies away. Sometimes a hairy woodpecker or a red-bellied woodpecker will return to use a cavity for night roosting. Oftentimes who "wins" the cavity seems to depend on size—hairy woodpeckers will chase away downy woodpeckers, and red-bellied woodpeckers will chase away hairys. Flickers will chase away red-bellied woodpeckers, and pileated woodpeckers are generally not chased away by much, at least in the fall (with the exception of a feisty exchange with a red-headed woodpecker).

Bluebirds also appear to be very attracted to vacated red-headed woodpecker cavities. We know from many nest checks over the last several years that they will nest inside previously used red-headed woodpecker cavities during the breeding season. Videos we have reviewed from last fall have not captured any bluebirds going inside cavities—they sit at the hole looking in, sometimes in pairs or small groups, hanging around for several hours and will sometimes defend them from other birds, including other bluebirds. It may be that they want a cavity handy in case a predator, like an owl or hawk, shows up so they have a place to hide. Interestingly, the peak time the bluebirds were present in these videos was also the peak time for raptor migration.

The videos below show a snapshot of a few bluebirds sitting at cavity entrances, flying around them, feeding, and sometimes interacting briefly with other birds, including a hairy woodpecker and a white-breasted nuthatch.

The three photos below show a fast exchange between two bluebirds. The bluebird sitting on the branch attacks the second bluebird that arrives at the cavity, which may be a territorial behavior of some kind.

We hope you enjoy these images and videos as much as we do and we'll be sure to bring you more information on our Zooniverse project as soon as we are able. Here's to a safe, healthy and productive 2021!

Article by Elena West and Siah St. Clair.


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