Black-billed Magpie Research Articles

Egg Recognition in Yellow-Billed and Black-Billed Magpies in the Absence of Interspecific Parasitism: Implications for Parasite-Host Coevolution

Egg Recognition in Yellow-Billed and Black-Billed Magpies in the Absence of Interspecific Parasitism: Implications for Parasite-Host Coevolution

Development of object permanence in food-storing magpies (Pica pica).

The development of object permanence was investigated in black-billed magpies (Pica pica), a food-storing passerine bird. The authors tested the hypothesis that food-storing development should be correlated with object-permanence development and that specific stages of object permanence should be achieved before magpies become independent. As predicted, Piagetian Stages 4 and 5 were reached before independence was achieved, and the ability to represent a fully hidden object (Piagetian Stage 4) emerged by the age when magpies begin to retrieve food. Contrary to psittacine birds and humans, but as in dogs and cats, no "A-not-B error" occurred. Although magpies also mastered 5 of 6 invisible displacement tasks, evidence of Piagetian Stage 6 competence was ambiguous.

EGG RECOGNITION IN YELLOW-BILLED AND BLACK-BILLED MAGPIES IN THE ABSENCE OF INTERSPECIFIC PARASITISM: IMPLICATIONS FOR PARASITE-HOST COEVOLUTION

Abstract Yellow-billed Magpies (Pica nuttalli) ejected 100% of nonmimetic eggs placed in their nests despite such behavior having no detectable present day benefits. They are not currently parasitized, nor is there any evidence of a recently extinct brood parasite. Furthermore, there was no molecular evidence of conspecific parasitism, and Yellow-billed Magpies accepted eight of nine conspecific eggs transferred between nests, so recognition would rarely be of benefit if conspecific parasitism occurred. Thus, we suggest that egg recognition in Yellow-billed Magpies is a plesiomorphic trait, a primitive character inherited from a remote ancestor, its nearest relative, the Black-billed Magpie (Pica pica). The latter suffers from parasitism by Great Spotted Cuckoos (Clamator glandarius) in Eurasia and displays rejection behavior throughout Europe in populations that are allopatric and sympatric with this cuckoo. As would be expected if Yellow-billed Magpies inherited rejection behavior from the Black-billed ...

Black-billed Magpie (Pica hudsonia)

Black-billed Magpie (Pica hudsonia)

Black-billed Magpie (Pica hudsonia)

Black-billed Magpie (Pica hudsonia)

Functional morphology of the hindlimb musculature of the black-billed magpie, Pica pica (Aves, Corvidae)

In spite of the ecological relevance of terrestrial locomotion for many bird species, this function remains poorly studied to date. Gait preferences and transitions seem present, but it is not known which factors might determine the running style. Morphological and morphometric data needed for further biomechanical modelling are presented for the black-billed magpie (Pica pica), a species which walks, runs and hops. Detailed descriptions of the muscle–tendon systems and the attachment sites on the hindlimb skeleton are given. Pinnation angles, fibre lengths and muscle masses are determined. From the latter two, physiological cross-sections of the muscle bundles are calculated. Tendon ossifications are qualitatively scored. Further, information on the mechanical variables of the body segments are collected (i.e. mass, length, position of the centre of gravity and moment of inertia of digits, tarsometatarsus, lower leg, upper leg, body, and head/neck). Moment arms of the important muscles powering terrestrial locomotion are discussed and, for some upper leg muscles, an equation to calculate the moment arms as a function of knee and hip joint angles is presented. All these data are indispensable for further kinesiological research.

Hand-Rearing Corvids for Reintroduction: Importance of Feeding Regime, Nestling Growth, and Dominance

Captive propagation has become increasingly important in preventing extinction in many avian species, including the Hawaiian crow (Corvus hawaiiensis) and Mariana crow (C. kubaryi). We used 3 surrogate species, common raven (C. corax), American crow (C. brachyrynchos), and black-billed magpie (Pica pica), to develop eaptive-rearing protocols for endangered corvids. Here we compare the health, growth, and survival among nestlings hand-reared on 14 feeding regimes. Frequency of feeding chicks for the first 2 weeks after hatch varied from once every 30 min to once every 2 hr. From 2 weeks until near fledging age, frequency of feeding varied from once every hour to once every 3 hr. Initial amounts of food fed varied from unlimited (ad libitum) to a restricted amount (a total of 15, 25, or 40% of a chick's body mass). Combinations of frequent feeding and large amounts of food produced fast-growing, heavy birds with few fault bars in their feathers, but all hand-reared nestlings grew more slowly than wild-reared chicks. Initial amount of food offered to day-old chicks affected growth and survival more than frequency of feeding in very large passerines (e.g., common ravens). In small- to medium-sized passerines (e.g., black-billed magpies, American crows), frequency of feeding affected growth and survival more than initial amount of food.

Rapid decline of host defences in response to reduced cuckoo parasitism: behavioural flexibility of reed warblers in a changing world

On Wicken Fen and nearby watercourses eastern England, parasitism by cuckoos, Cuculus canorus, declined from 26 and 16 of reed warbler (Acrocephalus scirpaceus) nests in 1985 and 1986, respectively...

Interactions between Black-Billed Magpie and Fallow Deer

Black-billed Magpies (Pica pica) were observed pecking on fallow deer (Dama dama) on 56 occasions. Ectoparasite removal was apparently the reason for this interaction. Birds preferred deer that were sitting to deer that were standing, and interacted preferentially with adult males over females or calves. Deer did not solicit cleaning and, on a few occasions, were observed to shake off birds. This interaction may be beneficial for magpies, because ectoparasites are a predictable source of food, but its effect on fallow deer remains to be investigated.

Mechanical power output of bird flight

Aerodynamic theory predicts that the power required for an animal to fly over a range of speeds is represented by a ‘U’-shaped curve, with the greatest power required at the slowest and fastest speeds, and minimum power at an intermediate speed1,2,3,4,5,6. Tests of these predictions, based on oxygen consumption measurements of metabolic power in birds7,8,9,10,11,12 and insects13, support a different interpretation, generating either flat or ‘J’-shaped power profiles, implying little additional demand between hovering and intermediate flight speeds14. However, respirometric techniques represent only an indirect assessment of the mechanical power requirements of flight and no previous avian study has investigated an animal's full range of attainable level flight speeds. Here we present data from in vivo bone-strain measurements of pectoralis muscle force coupled with wing kinematics in black-billed magpies (Pica pica ), which we use to calculate mechanical power directly. As these birds flew over their full range of speeds, we offer a complete profile of mechanical power output during level flapping flight for this species. Values of mechanical power output are statistically indistinguishable (that is, the power curve is flat) over most forward-flight speeds but are significantly higher during hovering and flight at very low speeds.

Flight style of the black-billed magpie: variation in wing kinematics, neuromuscular control, and muscle composition.

Black-billed magpies (Pica pica; Corvidae) exhibit an unusual flight style with pronounced, cyclic variation in wingbeat frequency and amplitude during level, cruising flight. In an effort to better understand the underlying internal mechanisms associated with this flight style, we studied muscle activity patterns, fiber composition of the pectoralis muscle, and wingbeat kinematics using both laboratory and field techniques. Over a wide range of speeds in a windtunnel (0-13.4 m s-1), wingbeat frequency, wingtip elevation, and relative intensity of electromyographic (EMG) signals s-1 from the flight muscles were least at intermediate speeds, and increased at both slower and faster speeds, in approximate agreement with theoretical models that predict a U-shaped curve of power output with flight speed. Considerable variation was evident in kinematic and electromyographic variables, but variation was continuous, and, thus, was not adequately described by the simple two-gait system which is currently accepted as describing gait selection during vertebrate flight. Indirect evidence suggests that magpies vary their flight style consistent with reducing average power costs in comparison to costs associated with continuous flapping at a fixed level of power per wingbeat. The range of variation for the kinematic variables was similar in the field and lab; however, in the field, proportionally fewer flights showed significant correlations between wingbeat frequency and the other variables. Average flight speed in the field was 8.0 m s-1. Average wingbeat frequency was less in the field than in the windtunnel, but mean values for wingtip elevation and wingspan at midupstroke were not significantly different. Histological study revealed that the pectoralis muscle of magpies contained only fast-twitch (acid-stable) muscle fibers, which were classified as red (R) and intermediate (I) based on oxidative and glycolytic capacities along with fiber diameter. This fiber composition may be related to variation in wingbeat kinematics, but such composition is found in the pectoralis of other bird species. This suggests that the muscle fibers commonly found in the pectoralis of small to medium sized birds are capable of a wider range of efficient contractile velocities than predicted by existing theory. Future studies should explore alternative explanations for variation in wingbeat kinematics, including the potential role of nonverbal communication among cospecifics.

Courtship Behavior of a Pair of Black-Billed Magpies

Courtship Behavior of a Pair of Black-Billed Magpies

The effects of the wingbeat cycle on respiration in black-billed magpies (Pica pica)

Interclavicular and posterior thoracic airsac pressures, tracheal airflows and pectoralis muscle activity were recorded simultaneously to determine the effect of the wingbeat cycle upon the function of the respiratory system. The effects of the wingbeat cycle on the relative positions of thoraco-abdominal skeletal structures were also assessed using high-speed X-ray cinematography of magpies Pica pica flying in a windtunnel. We found that the furcula bends laterally on the downstroke and recoils medially on the upstroke, as previously described for starlings, and that the coraco-sternal joint (the most consistently visible point on the sternum for digitization) is displaced dorsally during the downstroke and ventrally, with respect to the vertebral column, during the upstroke. In magpies, there are generally three wingbeat cycles during a respiratory cycle. When downstroke occurs during inspiration, its compressive effect reduces the inspiratory subatmospheric airsac pressure by an average of 92 % (0.35 kPa), whereas when upstroke occurs during expiration its expansive effect can reduce the expiratory supra-atmospheric airsac pressure by 63 % (0.23 kPa). Corresponding changes occur in tracheal airflow. Changes in respiratory parameters during short flights with respect to resting values include a doubling of tidal volume and a tripling of respiratory frequency. We conclude that the wingbeat cycle can have a substantial impact on respiratory system function in the flying magpie, and that this represents a mechanical basis for breathing patterns and patterns of phasic coordination between wingbeat and respiratory cycles that may result in minimal interference and maximal assistance from the wingbeat upon the respiratory cycle.

Coordination of respiratory cycles with wingbeat cycles in the black-billed magpie (Pica pica)

Magpies fly with a variable pattern of wingstroke, including high-amplitude rapid flaps and low-amplitude slower flaps with interspersed brief glides. This allowed us to test the hypothesis that if phasic coordination between respiratory and wingbeat cycles is important mechanically and energetically, then, as a bird changes its wingbeat cycle, its respiratory cycle should change with it. We also tested the strength of the drive to coordinate respiratory to locomotor cycles by stimulating breathing with 5 % CO2 during flight. We found that magpies (N=5) do shorten their breath cycle time when they shorten their wingbeat cycle time and prolong their breath cycle time when they glide. When the coordination ratio of wingbeat cycles to breaths is 3:1, the pattern of phasic coordination ensures two upstrokes per inspiration and two downstrokes per expiration. Upstroke tends to coincide with the transition into inspiration or with early inspiration and late inspiration. Downstroke tends to coincide with the transition into expiration or with early expiration and late expiration. When magpies switch from a 3:1 ratio to a 2:1 ratio of wingbeat cycles to breaths, they shorten inspiratory time to ensure that upstroke occurs through most of inspiration and downstroke corresponds to the transition into expiration. These phasic coordination patterns ensure that the compression of the airsacs during downstroke can provide a net assistance to expiration and that the expansion of the airsacs with upstroke can provide a net assistance to inspiration. The failure of an atmosphere containing 5 % CO2 to disrupt these phasic coordination patterns between respiratory and locomotory cycles suggests that there may be a potent mechanical and energetic benefit to such coordination.

Female red-winged blackbirds accrue material benefits from copulating with extra-pair males

This study tested whether female red-winged blackbirds,Agelaius phoeniceusacquire non-genetic, material benefits from copulating with multiple males. In this population, females solicit extra-pair copulations, primarily from males defending adjacent territories on the same breeding marsh. Results of a feeder experiment revealed that females that copulated with an extra-pair male were allowed to feed on his territory, but females that remained faithful to their social mates were actively excluded from foraging on neighbouring territories. Males discriminated between faithful and unfaithful social mates. Females that engaged in extra-pair copulations were prevented from foraging on their social mate's territory significantly more often than females that did not. Measurement of neighbouring male responses to a mounted nest predator, a black-billed magpie,Pica picarevealed that males were also significantly more aggressive towards a predator at a nest on a neighbouring territory if they had copulated with the breeding female than if they had not. These findings provide a possible explanation for results of Gray (1997,Anim. Behav.53, 605–623), which showed that fledging success was significantly higher for females that engaged in extra-pair copulations than for females that did not, because depredation rates were significantly lower in clutches laid by females that had engaged in extra-pair copulations, and starvation rates tended to be lower in broods containing extra-pair young. This study is the first to demonstrate that females can benefit materially as well as genetically by copulating outside their pair bond and illustrates the need for manipulative tests to understand fully the reproductive strategies of individuals in populations where social relationships often do not reflect genetic relationships.

Regurgitated pellets and late winter diet of Black-billed Magpies, Pica pica, in central Alberta

Regurgitated pellets and late winter diet of Black-billed Magpies, Pica pica, in central Alberta

Sex determination of the Black-billed Magpie, Pica pica

Sex determination of the Black-billed Magpie, Pica pica

Roost characteristics and roosting behaviour of Black-billed Magpies, Pica pica, in Edmonton, Alberta

Roost characteristics and roosting behaviour of Black-billed Magpies, Pica pica, in Edmonton, Alberta

Density-Dependent Reproductive Success Is Mediated by Nest Predation in Black-Billed Magpies (Pica pica)

Density-Dependent Reproductive Success Is Mediated by Nest Predation in Black-Billed Magpies <i>(Pica pica)</i>

The Effect of Magpie Breeding Density and Synchrony on Brood Parasitism by Great Spotted Cuckoos

Nesting density and synchrony by hosts may indirectly serve as a defense mechanism against brood parasites. Here we examine the relationships between spatial and temporal distribution of host nests and the probability of being parasitized. We use as host species the Black-billed Magpie (Pica pica), a species that is parasitized by the Great Spotted Cuckoo (Clamator glandarius) in southern Europe. We also examined the differences in parasitism rate in nearby plots that differ in magpie social organisation. Results show that increased proximity to other nests and specially laying synchrony both reduced the probability of being parasitized. Consequently, magpies breeding synchronously in dense plots may experience an indirect advantage against brood parasitism with respect to low density, low synchrony plots.