|ognizant Communication Corporation|
VOLUME 16, NUMBERS 1-2
Bird Behavior, Vol. 16, pp. 1-6
1056-1383/04 $20.00 + .00
Copyright © 2004 Cognizant Comm. Corp.
Printed in the USA. All rights reserved.
Responses of Captive Fish Crows (Corvus ossifragus) to Acetaminophen Baits and Bait Stations for Brown Tree Snake (Boiga irregularis) Control on Guam
Michael L. Avery,1 Eric A. Tillman,1 and Peter. J. Savarie2
1National Wildlife Research Center,
USDA/APHIS/Wildlife Services, 2820 East University Avenue, Gainesville,
2National Wildlife Research Center, USDA/APHIS/Wildlife Services, 4101 LaPorte Avenue, Fort Collins, CO 80521
One component of brown tree snake (Boiga irregularis) management on Guam is the use of a toxic bait that consists of acetaminophen tablets inserted into a dead neonatal mouse (DNM), which in turn is placed within a cylindrical polyvinyl chloride (PVC) bait station suspended above ground. Whereas this technique is effective in killing snakes, possible hazards to nontarget species, especially the Mariana crow (Corvus kubaryi), are of concern. We used the fish crow (C. ossifragus) as a surrogate for the Mariana crow to evaluate (1) oral toxicity of acetaminophen, (2) behavior of crows exposed to DNM containing acetaminophen tablets, and (3) ability of crows to remove DNM from cylindrical bait stations. In the oral toxicity test, all five crows that were each force-fed two 40-mg acetaminophen tablets survived and at least two birds regurgitated the tablets. Five additional crows received a double dose (four 40-mg tablets); each regurgitated all of its tablets, but one bird died. Crows given DNM containing two 40-mg acetaminophen tablets consumed the DNM but avoided eating tablets by picking them from the carcass and either setting them aside or dropping them from the perch. Forty individually caged crows were tested with various size bait station cylinders containing an untreated DNM. Only the longest (45.7 cm), narrowest (5.1 cm) cylinder prevented crows from removing the DNM. In brown tree snake control operations, it appears that the risk of accidental exposure of Mariana crows to toxic acetaminophen bait can be minimized through appropriate bait station design. Even if crows encounter a DNM containing acetaminophen, they are likely to reject the tablets before consumption or regurgitate if tablets are accidentally ingested.
Key words: Acetaminophen; Bait station; Fish crow; Brown tree snake
Mate Switching Patterns in Crested Auklets (Aethia cristatella): The Role of Breeding Success and Ornamentation
Gail S. Fraser,1 Ian L. Jones,2 Fiona M. Hunter,3 and Laura Cowen4
1Biopsychology Programme and 2Department
of Biology, Memorial University of Newfoundland
3Animal and Plant Sciences, Sheffield University
4Department of Statistics and Actuarial Science, Simon Fraser University
We evaluated the causes and consequences of mate switching in crested auklets (Aethia cristatella). The crested auklet is a small seabird in which both sexes are similarly ornamented and contribute to parental care. We observed 29 pairs and found that 31% changed mates between breeding seasons. In a logistic regression analysis, we used absolute crest length, breeding success, body condition, and the interaction of crest lengths, in year 1, for males and females to predict the likelihood of switching mates in year 2. The best model predicted that female crest length influences the likelihood of mate switching; specifically, short-crested females were more likely to split up between breeding seasons. A benefit associated with mate switching was that individuals that changed mates were more likely to obtain a new mate with a longer crest. One cost identified with switching mates was a delayed hatch date, although chick quality did not appear to be compromised. Distinct differences in behavior and body morphology exist between males and females; therefore, assumptions that the sexes experience similar costs or benefits in switching mates may not be valid.
Key words: Seabird; Mate fidelity
Socially Learned Antipredator Behavior in Black-Capped Chickadees (Poecile atricapillus)
Myron C. Baker
Biology Department, Colorado State University, Fort Collins, CO 80523
Few experiments have addressed the question of whether birds can learn an antipredator response through the action of social modeling by a conspecific demonstrator. Whereas social learning of predator characteristics could be the basis of culturally transmitted traditions in natural populations, little experimental evidence exists to support the hypothesis of a social transmission mechanism in birds. In the experiment reported here, I used demonstrator black-capped chickadees (Poecile atricapillus), responding to their viewing of a stuffed sharp-shinned hawk (Accipter striatus), to induce observer chickadees to react with antipredator behavior toward a nonpredator model of a duck (cinnamon teal, Anas cyanoptera). Observer chickadees had a low antipredator vocal response to the duck prior to social modeling by the demonstrators and a high level of vocal response during the demonstrator phase, at which time the two chickadees could see each other but not each other's stimulus. Following the demonstration phase, observers exposed to the duck for the third time had a somewhat lower vocal response, though not significantly so, than during the demonstration phase. These results are consistent with the hypothesis that learning of predator characteristics by inexperienced birds can occur in the context of antipredator behavior being exhibited by experienced conspecifics.
Key words: Predator learning; Predator mobbing; Bird vocalizations
Conspecific Vocalizations Are Not Sufficient to Alter Food-Caching Behavior in Black-Capped Chickadees (Poecile atricapillus)
David E. Gammon and Myron C. Baker
Biology Department, Colorado State University, Fort Collins, CO 80523-1878
Although a number of studies have shown that the presence of conspecific flock members has a negative influence on caching behavior in food-hoarding bird species, the role of different cues (e.g., visual, vocal) that a caching bird uses in detecting potential cache robbers has not been studied. Flock members are frequently in vocal, but not visual, contact. We played gargle, tseet, and chick-a-dee vocalizations to foraging black-capped chickadees (Poecile atricapillus) in a laboratory caching environment to see if vocalizations alone would affect caching behavior. We measured the time to first cache and total number of food items cached and found that birds did not alter caching behavior in response to playback. We conclude that vocalizations alone are not sufficient to affect the caching behavior of black-capped chickadees.
Key words: Black-capped chickadee; Food storage; Vocalizations
Use of Visual Cues in Artificial Flower Choice by Hummingbirds (Archilochus colubris): Color or Shape?
F. Landry, M. Perreault, and C. M. S. Plowright
School of Psychology, University of Ottawa
In a field study, two groups of hummingbirds were trained to discriminate between a rewarding (S+) and an unrewarding (S+) feeder that differed only in the distinctive color and shape combination associated with each. The birds were subsequently tested for their choice between unrewarding feeders on which the color and shape associations were decoupled. For example, after having learned to discriminate between a white heart (S+) and green square (S-), they were given a choice between a green heart and white square, neither of which offered reward. On their first choice all birds selected the stimulus with the same shape as the S+, even though it was of a different color, showing that color is not necessarily a privileged dimension over shape in floral discriminations.
Key words: Hummingbirds; Color and pattern preferences; Discrimination learning; Foraging choices