Three of a Kind-- Communal Roosting by Pacific Wrens

It’s fascinating when a species so common that we take it for granted surprises us from time to time. Here in Victoria, BC, Canada, Pacific Wren (the bird formerly known as Winter Wren) is a daily occurrence anywhere there is suitable habitat. This species is best known for its amazing torrent of song and equally impressive talent for staying well-hidden in the forest understory. Imagine my surprise when I discovered a Pacific Wren roosting on an open ledge right above the back door in my carport. Starting in the winter of 2006, I began to notice droppings next to the stairs, and knew that something was roosting there at night. Treading lightly and using a small flashlight, I discovered an unidentifiable ball of fluff tucked into one of the corners of the ledge. After several attempts at taking photos, sneaking surreptitious peeks during the night and, eventually, accidentally flushing it by arriving home at just the wrong time, the bird was finally identified as a Pacific Wren. I was delighted to share the carport and immediately made new house rules: No loud noises in the carport after dusk; only sneaky peeks at the bird to check on its welfare (and to show it to friends, of course!); and tolerance for the ever-increasing accumulation of wren droppings. Bird nut? Who, me?

This screen grab, taken from video recorded using an infrared wireless video camera, shows three Pacific Wrens huddled together. Notice that the outer birds are facing the edge of the ledge, while the middle bird is faced the other direction with its tail hanging over the ledge.  

Each winter, the wren (or a lookalike) would return to the roost, only to depart when the allure of breeding pulled it away for the summer. On the stormiest and coldest nights, though, it was conspicuously absent. Worried about its survival, I’d check the roost only to find it empty. There was more than one occasion that I thought for certain that it must have died, only to see new droppings a few days later when the weather settled down. It must have had a warmer, more protected spot for those colder nights.

In February, 2009, this species surprised me yet again. One night, I lit up the roost to see if the wren was there and found not one, but TWO wrens on the ledge. Wow! I wondered if this was a pair and if Wren One had brought Wren Two to the ledge as part of its courtship. As luck would have it, I had recently purchased an infrared wireless IP camera which was quickly repurposed to be a wren-roost spycam. I mounted it in the carport that day while the wrens were away and got set for an evening of discovery. My placement of the camera was poor, and all I got were some grainy, difficult to see images, but enough to determine that there were not two wrens, but THREE!! Communal roosting! Who knew?! Well, it turns out that some people did know (as many as 31 found huddled together in a nest box in western Washington in December 1924), but this was exciting news for me. I repositioned the camera and for the next week or so, spent several hours a day reviewing the nocturnal adventures of the wrens. Here’s what I learned 

Pacific Wrens are very itchy birds. Before settling (and I use that word loosely) down for the night, a wren can spend several minutes scratching, fluffing, preening, scratching, picking, scratching, and then more scratching. When it is anticipating others, it looks for them. The first wren to the roost would lean over so that it could see under the beam, watching for the roostmates to arrive. A similar posture was taken when the wrens departed in the morning. When one wren took off, the others would lean over the edge and watch it go. The party really started when all of the expected tenants had arrived at the roost. I like to call it “Three Wren Monte” (video link). The birds hopped, fought, and clambered over each other to determine who got to sleep where. It appeared the most desirable spot was the one in the middle, with the bird’s tail hanging over the edge of the ledge. More on that later. Of course, this spot would be the warmest and most protected, so procuring it was worth a little bickering. The birds lined up head to tail; the typical arrangement involved the outer birds facing out, and the lucky middle bird facing in. Once the positions had been set, the three birds would all fluff up and form a ball of feathers the size of a large orange. I’ve seen photos of other roosting birds, and it’s amazing how the fluffing can turn a bird into something unrecognizable. Good idea if you’re sleeping among the enemies! This was my first view of communal camouflage.

A good night's sleep was not in the cards for these wrens. About every half hour or so, someone had to answer a different call of nature. When it was the middle bird, whose tail was already hanging over the ledge, there was no problem. A slight stretch and “plop”, the deed was done. However, when it was one of the outer birds, chaos ensued. The bird would have to turn around, disrupting the orb of warmth, much to the dismay of the ledgemates. Then the shuffling, scratching and a new game of three wren monte would begin again (Nature Calls video link). I can’t say if there was any rhyme or reason as to who got to be in the middle for the next shift, but it appeared that at least some of the time, positions were switched.

Morning departure was much more leisurely than I expected. The wrens awoke around first light, then spent up to half an hour getting ready for their day (The Morning Routine video link). Stretching, scratching, fluffing, preening, hopping around the ledge, more scratching … did I mention that they are very itchy birds? When the first wren would finally decide to leave, the other two would hang from the edge of the ledge to see where it went. Within a couple of minutes, the others would follow, leaving the ledge empty for the day.

This wren appears to be sneaking a peek a the camera, perhaps attracted to the red light or some noise. 

It’s been two years since I recorded the antics of these three wrens on my carport ledge, but the roost is still occupied. This year, I have seen one or two wrens roosting in the usual location,  but I’m not sure that either of them is one of the original birds. The Bird Banding Lab (2011) shows the longevity records for Winter Wren to be just over five years. That bird was released alive, so it is presumed ot have lived at least a while longer. My suspicions about the current tenants are due to their behaviour. Wren One was very tolerant of my comings and goings, and rarely woke up because of my activities or my flashlight. When I’ve checked the roost this year, I’m almost always looking at the face of a wren looking back at me. They stay put, though, so while aware of me and perhaps a bit nervous, they seem to understand that they are relatively safe where they are.

Things I've learned about the roosting habits of Pacific Wrens:

* Pacific Wrens sometimes roost communally in the winter.

* They are loyal to their roosts, but have more than one for different weather conditions. My carport is excellent protection against predators and rain, but not so great for extreme cold.

* They seem to be able to communicate with each other about good roost sites, and may even pass them along to the next generation.

* They are aware of changes at the roost site. They looked directly into the camera on several occasions, even in the darkness. One climbed up on wiring to have a closer look. Either they could see the red glow of the infrared lights, or otherwise detected that a new object (the camera) was there. It didn’t seem to bother them, but they were aware.

* They “talk” to each other at the roost. I recorded high-pitched squeaking sounds that I haven’t heard from Pacific Wrens in the field.

* They look for each other during arrivals and departures.

I love that familiar birds can still teach us new things. There’s always a reason to keep watching!

All videos and still screen grabs recorded by Ann Nightingale