Everyone knows that house cats and wild birds are not the best of friends. Cats that wander yards and forest edge are likely to pick off a lot of birds, especially vulnerable young at fledging time. Follow a cat around and you’re sure to discover that adult birds pay close attention to the cat’s movements, and respond with alarm calls that key you in to the whereabouts of the cat.
Such was the case with Otis, our neighbor’s cat. A few days ago, when I was recording a juvenile Carolina Wren practicing his newly-acquired song repertoire (Carolina Wren-Teenage Song), I came across Otis on several occasions. Twice I was alerted to his presence by alarmed birds … first by an American Robin and later by a Gray Catbird. In the third instance, I watched Otis approach the shrub where my wren-subject was practicing his songs. As expected, the wren soon took notice and responded with alarm calls. Luckily, I was able to record all three instances, and my recordings are presented below in the order that I made them.
I heard the robin calling while I was sitting on my doorstep, tying my shoes. Walking in his direction, I soon located him perched on a limb at the edge of the woods, about fifteen feet off the ground. He appeared to be an adult male and he had food in his mouth. It was then that I noticed Otis slowly making his way through the understory (I presume the robin was headed to feed young when he spied Otis below). The robin didn’t seem hugely concerned, but he did perch motionless on a limb above the cat, giving a slow-paced series of moderately excited “tut” calls, one of the robin’s two most common alarm calls (the other is a sharp “peek!”):
As Otis moved away from the robin’s territory, the robin settled down and flew into the woods. I went on my way in search of the juvenile wren. About five minutes later, I heard a Gray Catbird alarming from dense shrubs at the edge of the yard. As I approached, I again noticed Otis, moving slowly through the thicket. The Catbird was perched directly above him and was giving throaty “kwut” calls, the standard alarm call given when a predator comes close to a Catbird’s nest or to fledglings. Like the robin, he didn’t seem overly upset, but he was certainly vigilant, and he continued to call until Otis left the scene.Gray Catbird responding to a Otis the cat, early am, July 3, 2012, near Ithaca, NY
The most interesting alarm response (at least from my point of view) was that of my little wren. I was happily recording wrensong when I spied Otis approaching. My wren soon took notice and flew deep into the shrub. I lost sight of him momentarily, but I could hear him giving harsh chattering or rattling alarm calls (harsh rattles are typical of alarmed wrens of several species and both male and female Carolina Wrens give them). After rattling several times, my little wren began giving down-slurred “cheer calls, which sound somewhat musical to the ear. The “cheer” is the male Carolina Wren’s special concern call and it is often given in response to predators. In the recording below, listen for the harsh rattles followed by cheer calls and finally song, the latter being given only after Otis disappeared from view (return to song signifies that all is well in the world of the wren). A catbird sings in the background.Juvenile male Carolina Wren responding to a Otis the cat, early am, July 3, 2012, near Ithaca, NY
Interestingly, none of the three birds seemed hugely upset. My take on this is that they are all quite familiar with Otis. While Otis certainly represents a danger, if a bird sees him and there are no fledglings or nestlings in direct danger, then he is not a huge threat. Therefore, a mild alarm response is appropriate.
Learning to recognize the alarm calls of birds alerts one to the presence of predators. On occasion one may witness a disaster, such as when a cat seizes a helpless fledgling that has fallen to the ground (the parent birds respond with super-intense alarm calls in such cases). Most of the time, however, birds are only mildly threatened, especially when the predator is below them on the ground and is not approaching nest or young. This seemed to be the case here. All three birds were clearly concerned about Otis and acknowledged his presence through alarm calls, but none responded with great intensity and all went on their merry way within seconds of Otis moving away.
Otis is probably a familiar fixture in the lives of all three birds, and they probably don’t consider him to be a major threat except under exceptional circumstances. For instance, if Otis discovers an active nest or approaches a fledgling, he will instantly be transformed into a high-threat mortal enemy and the birds will respond as if their lives depend on it. Wouldn’t you?