These noisy, social birds (12-13.5 in long) have a charcoal head and a blue body, wings, and tail.The tail is long, and they have a large triangular crest on top of their head.. Steller's Jay live in flocks except when nesting. They seem to wreak havoc wherever they go, bouncing between trees in small groups and loudly dominating the feeders at your deck. These different hunting strategies present different threats and animals should respond to these differences. The birds are also consummate mimics, using predator calls to scare other birds away from feeders. 1980), body size (Templeton et al. Head movements were controlled by an Arduino computer (Arduino, Torino, Italy). 1999). © Copyright 2020 WRA Wildlife Rescue Association of British Columbia. We slowly lowered and raised the false tree trunk from a distance (approximately 15â20 m) using a modified radio-controlled garage door opener. DL 2005), hunting strategy (Sherbrooke 2008), behavior (Marler 1955; Lima and Dill 1990; Caro 2005; Bradbury and Vehrencamp 2011), distance (Stankowich and Coss 2006), or habitat (Eggers et al. When Stellerâs jayâs saw a northern goshawk, they gave more wah calls (Stimuli Ã Exposure Ã Cue: Ï2 = 33.88, df = 10, P < 0.001) in comparison to all the other stimuli (Figure 4a; visual goshawk vs. visual sharp-shinned: P = 0.017; visual goshawk vs. visual pygmy-owl: P < 0.001; visual goshawk vs. visual control: P < 0.001; visual goshawk vs. acoustic sharp-shinned: P < 0.001; visual goshawk vs. acoustic pygmy-owl: P < 0.001; visual goshawk vs. acoustic control: P < 0.001) with more wah elements (Stimuli Ã Exposure Ã Cue: Ï2 = 16.99, df = 10, P = 0.075) than to all the other stimuli except seeing a sharp-shinned hawk (Figure 4b; visual goshawk vs. visual sharp-shinned: P = 0.937; visual goshawk vs. visual pygmy-owl: P = 0.004; visual goshawk vs. visual control: P = 0.010; visual goshawk vs. acoustic sharp-shinned: P = 0.010; visual goshawk vs. acoustic pygmy-owl: P = 0.037; visual goshawk vs. acoustic control: P = 0.002). Predator stimuli chosen for the differences in size (small vs. large) and hunting strategy (pounce vs. chase). They can even echo the call of a cat or a dog, which must be useful for securing a feeder or some scattered peanuts to themselves. In contrast, acoustic cues about predators are more ambiguous, as there is less certainty about the predatorâs identity, location, movement, and behavior (Billings et al. We ran the red-tailed hawk mimetic calls with only acoustic stimuli (5 levels: Townsendâs solitaire, northern pygmy-owl, sharp-shinned hawk, red-tailed hawk, northern goshawk) and exposure period (2 levels: exposure, postexposure) as fixed effects and with feeder location (18 levels) as a random effect. SD Group mobs will incorporate the use of “wah” calls to produce a loud ruckus to help drive of threats (Sibley 2001). The same subspecies of Stellerâs jay, Cyanocitta stelleri annectens, occurs at both of these sites (Walker et al. Cheney S 2 3 4. For the visual cue experiments, we recorded vocalizations with a Sennheiser omnidirectional microphone (Sennheiser, Wedemark, Germany) and a Roland R-26 recorder (Roland, Hamamatsu, Japan) at 48 kHz sampling rate and 24-bit depth. Predators differ in their risk to prey and predator detection cue types differ in the information they provide to prey. Seyfarth Mitchell In contrast, when jays hear a predator, they know its general location but not much else about it. Because we were unable to identify individuals within the flocks, this was meant as a measurement of the flock response to the stimuli. Wildlife Rescue Association of British Columbia Previous studies have shown that information about predators can be encoded in different ways. The longer they stayed away from the feeder the more threatening the predator. Maechler Eggers We did not have a robotic red-tailed hawk but it would be very interesting to test whether Stellerâs jays mimicked red-tailed hawk calls when they see (but not hear) a red-tailed hawk. D To make the playback stimuli and avoid pseudoreplication, we created multiple exemplars from high-quality recordings from the Macaulay Library of Natural Sounds at Cornellâs Lab of Ornithology (Kroodsma 1989, 1990). Within a call type, there can be graded variation in acoustic characteristics such as elements per call (Templeton et al. We conducted playback experiments at 18 feeders during the winters of 2012â2015. Spectrograms of Stellerâs jay alarm calls. Kleindorfer 2005; Courter and Ritchison 2010; Sieving et al. Seconds to resume foraging. Sulloway We chose these species because they vary in body size, hunting strategy, and diet and thus pose different threats to Stellerâs Jays. The main predators of these jays are owls and hawks, although other animals or birds can be seen as predators to their eggs or young. Predators can vary in the risk they pose, depending upon the factors such as body size, maneuverability, hunting strategy, and diet. However, recent work has shown that the chickadee alarm calling system is more complex: When chickadees hear rather than see a predator, they respond differently to 2 small predators with different hunting strategies. We constructed linear mixed effects models using maximum likelihood for each of the 9 variables. There is no information on home ranges for winter flocks of Stellerâs jays. . Stellerâs jays are a good species to explore discrimination and communication about predator risk. Answer. Cues differ in their information content. . During the winter, Steller’s Jay eats seeds and nuts, berries and fruits, and may prey upon small invertebrates, small rodents, reptiles, and eats carrion and suet. . P GE Marler Lucon-Xiccato Nevertheless, these cases are preventable with some simple adjustments. For the average number of call variables (wah, wek, and red-tailed hawk mimics), we counted the number of each call type for the exposure period then averaged by the exposure period (2 min for acoustic playbacks and 4 min for robo-raptor presentations) and analyzed as an average per exposure period (e.g., for a given experiment, the number of wah calls were added and divided by the duration of the exposure period). Is a blue jay a predator? MacArthur-Waltz KE In response to hearing a red-tailed hawk, they stayed away significantly longer than when exposed to a northern pygmy-owl or control (acoustic red-tailed vs. acoustic pygmy-owl: P = 0.026; acoustic red-tailed vs. visual pygmy-owl: P = 0.280; acoustic red-tail vs. acoustic control: P = 0.004; acoustic red-tail vs. visual control: P = 0.077; Figure 3). All statistical analyses were done in R using the lme4 package with an Î± of 0.05 (Bates et al. JW TP And when they heard a sharp-shinned hawk, they gave more wah calls than the control and northern pygmy-owl (Figure 4a; acoustic sharp-shinned vs. visual sharp-shinned: P = 0.396; acoustic sharp-shinned vs. acoustic pygmy-owl: P = 0.002; acoustic sharp-shinned vs. acoustic control: P < 0.001; acoustic sharp-shinned vs. visual pygmy-owl: P = 0.018; acoustic sharp-shinned vs. visual control: P < 0.001) but they did not alter the number of wah elements per wah call or wek duty cycle like they did when they saw a sharp-shinned hawk. Spectrograms were made of each recording using Hann window type with a 50% overlap and a window size between 512 and 1150 samples. Colombelli-NÃ©grel J There was no effect of stimuli on just the duration of the wek elements (P = 0.908) or the intervals between the wek elements (P = 0.607) but only the ratio of wek element duration to wek interval duration (P = 0.023). Steller’s Jays are a common sight in the forests of the Western United States. Steller's jay (Cyanocitta stelleri) is a bird native to western North America, closely related to the blue jay found in the rest of the continent, but with a black head and upper body. Steller's Jays are omnivores, and their diets are about 2/3 vegetable-matter and 1/3 animal-matter. Steller’s Jays will also eat berries, wild fruit, insects such as beetles and bees. Because the information provided about a potential predator can vary depending upon how it was detected, antipredator behaviors may also vary with cue type. What eats a steller jay? Based on size, hunting strategy and diet, northern pygmy-owls probably pose the smallest threat to Stellerâs Jays. Thus, although sharp-shinned hawks are about the same size as Stellerâs Jays, because of their stealthy hunting strategy and diet comprised mainly of birds, they likely pose a moderate to high threat to Stellerâs jays. We presented flocks of Stellerâs Jays with stimuli of 4 species of raptorsânorthern pygmy owl (Glaucidium gnoma), sharp-shinned hawk (Accipiter striatus), red-tailed hawk (Buteo jamaicensis) and northern goshawk (Accipiter gentilis). and will often maintain a commentary of the predators movements with their rich array of calls and mimicry. Uetz Again, there were no differences between stimuli in the duration of the wah elements (P = 0.396) or the duration of the intervals between the wahs (P = 0.144), only in the ratio of wah element duration to interval duration. Prey can also detect predators with different senses, such as seeing, hearing, or smelling them. Sieving JS 2016) but in some places, they form large flocks. Creating dynamic environments for our cats is one way we can reduce the amount of time they spend outside – therefore lowering the number of cat attacks. Prey can also detect predators with different senses, such as seeing, hearing, or smelling them. . We presented wild Steller’s jays (Cyanocitta stelleri annectens) with visual cues (robotic raptors) or acoustic cues (call playbacks) of 4 different raptors to test how they assess risk and how this influences their alarm calls. Northern pygmy-owls are small owls (approximately 52 g, Holt and Peterson 2000) about half the size of Stellerâs jays (approximately 106 g; Walker et al. 1965; Sieving and Willson 1998; De Santo and Willson 2001). They did this by varying the number of wah calls, the number of wah and wek elements per call and the wah and wek duty cycle. It is not as simple as one predator being more threatening than another but instead Stellerâs jays are combining multiple sources of information to assess risk. Steller’s Jays are a familiar sight here in the redwoods of Northern California. We investigated the following 2 questions: 1) how do Stellerâs jays assess risk using different predator detection cues across different predators and 2) how do these factors influence their alarm calls? CN Red-tailed hawks are about 10 times as large (approximately 1000 g) as Stellerâs jays. 's beauty, the Steller's jay provides even the most amateur bird-watcher an interesting experience. We measured the latency to resume foraging of the flock as a proxy for threat level. M Finally, in all of our red-tailed hawk presentations, we never observed a predator come to the area in response to the playback or the mimetic calls as predicted if the mimetic calls function as fear screams (Curio 1976); so, it does not seem that they mimic red-tailed hawks to bring in other raptors to try and escape. Creating an incentive for our cats to stay inside is also a helpful tool since many cats roam outside due to boredom in their homes. These birds are a staple of the West and frequent visitors in campgrounds, parks, and picnic grounds. We did not have a robotic red-tailed hawk. AC 2015). 2005). However, more direct tests are needed of how the perceptual use of predator cues across different predators influences assessment of risk and alarm call behaviors. Furthermore, Stellerâs jays altered the acoustic structure of their alarm calls depending on the species of raptor and whether they saw or heard them. SM ML Bates Gribble There were very few red-tailed hawk mimetic calls to any of the visual stimuli and they were not significantly different from one another or the matched acoustic stimuli (P < 0.05). In order to minimize disturbance to Stellerâs jays before each experiment, the robotic birds were concealed by a tube of cloth painted to resemble a tree trunk. When the birds returned to feeding regularly and at least 1 jay was perched on the feeder we began the 2-min playback (exposure). 2005; Soard and Ritchison 2009; Fallow and Magrath 2010; Sieving et al. Thus, it does not seem that Stellerâs jays mimic raptor calls to deceive other jays so they can steal food (Flower et al. Because of the variability in weather from year to year not all feeders were visited every year so the sample sizes of each stimulus varied (NTownsendâs solitaire = 28; Nnorthern pygmy-owl = 28; Nsharp-shinned hawk = 30; Nred-tailed hawk = 29; Nnorthern goshawk = 28). Finally, for the ratio of element duration to interval duration (i.e., duty cycle), we took the ratio of the average element duration per stimulus and divided by the average element interval duration per stimulus. 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