Piñon seed assessment by the piñon jay, Gymnorhinus cyanocephalus

Ligon, J. David; Martin, Dennis J.

doi:10.1016/s0003-3472(74)80040-0

Cited by 36 publications

(6 citation statements)

References 3 publications

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“…A variety of possible mechanisms have been proposed in other species. For example: pigeons and chicks, Gallus gallus domesticus, prefer, or learn faster about, options that offer more consummatory activity even if the actual amount of food gained is the same (Wolfe & Kaplon 1941;Shettleworth 1985); piñ on jays, Gymnorhinus cyanocephalus, use bill-weighing to identify heavier seeds that contain an endosperm (Ligon & Martin 1974); and shore crabs, Caranus maenas, measure the dimensions and perhaps also weight of mussels, Mytilus adulis, by handling them in their chelae (Elner & Hughes 1978). In our experiment the time taken to deliver a reward, the time taken to consume it, its weight and the number of crumbs it contained were all directly proportional to its calorific content, meaning that the birds could have been using any of these cues to assess the value of a reward.…”

Section: Discussionmentioning

confidence: 99%

Accuracy of memory for amount in the foraging starling,Sturnus vulgaris

Bateson

Kacelnik

1995

Animal Behaviour

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Attempts to include psychological constraints in models of foraging behaviour differ in their assumptions concerning the accuracy of estimation of environmental parameters. Psychologists model estimation error as increasing linearly with the magnitude of a stimulus (Weber's Law), whereas behavioural ecologists either ignore error or assume it to be independent of stimulus magnitude. Studies on the estimation of time intervals have confirmed Weber's Law, but there are few data on the accuracy of estimation of amounts of food. Since the currency of most foraging models is the amount of food acquired per unit of time spent foraging, information on estimation of amount is required. Here, a titration method was used in which starlings chose between two cues. One colour signalled a standard food reward, and the other a reward that adjusted in magnitude according to the birds' choices: it increased when the standard was preferred and decreased when the adjusting option was preferred. There were two standards of 3 and 9 units of food, each of which was delivered at two rates to control for possible effects of rate of reinforcement on discrimination. The observed value of the adjusting option oscillated around a mean value slightly larger than that of the standard. The amplitude and period of these oscillations were larger when the standard was larger, independent of the rate of reinforcement. Also, molecular analysis showed that the probability of choosing the currently larger alternative increased as the relative difference between the adjusting option and standard increased. These results are consistent with Weber's Law applying to starlings' memories for amounts of food.

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Section: Discussionmentioning

confidence: 99%

Accuracy of memory for amount in the foraging starling,Sturnus vulgaris

Bateson

Kacelnik

1995

Animal Behaviour

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“…The latter not only will eventually destroy any remaining pulp, but also probably will make the fruit objectionable to dispersers from the early stages of infection through the production of toxins or other discouraging substances (Mirocha and Christensen 1974;Janzen 1977b). I do not know of any study demonstrating refusal of damaged fleshy fruits by dispersal agents (but see Salomonson and Balda [I9771 and Gilbert [I9801 for supporting evidence), although equivalent discriminative capacities have been documented for some seed-eating vertebrates (Ligon and Martin 1974;Sork and Boucher 1977;Bossema 1979). It is reasonable to assume that any impairment in the attractiveness of the part of the fruit designed to play precisely an attractive role will result in a decrease of the chance N o~~.…”

Section: Damage To Ripe Fruits By Nonvertebrate Agentsmentioning

confidence: 99%

Defense of Ripe Fruit from Pests: Its Significance in Relation to Plant-Disperser Interactions

Herrera¹

1982

The American Naturalist

227

143

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“…Like nutcrackers, Pifion Jays seldom remove inedible seeds from cones (4 of 197 seeds extracted were discarded). Seed discrimination is accomplished by "bill-clicking", "bill-weighing" and visual cues (LIGON and MARTIN 1974). All seeds we removed from the esophagi of Pifion Jays (n = 655) were edible.…”

Section: Foraging Behaviormentioning

confidence: 99%

“…Because seeds are stored whole and seed quality is not assessed directly (i.e. seeds are not opened), birds evolved behavioral techniques which allowed them to evaluate seed characteristics that indicate seed quality (LIGON and MARTIN 1974;VANDER WALL and BALDA 1977). Changes in bill morphology aiid behavior allowed birds to forage more quickly and extract seeds from unopened cones.…”

Section: Evolution Of Specialized Seed-storage Behaviormentioning

confidence: 99%

Ecology and Evolution of Food-storage Behavior in Conifer-seed-caching Corvids

Wall

Balda

2010

Zeitschrift Für Tierpsychologie

129

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The conifer‐seed‐collecting, transporting and storage behavior of four western North American corvids are described. A simple mathematical model is presented which relates: 1) distance seeds are transported, 2) total harvest time, and 3) foraging adaptations, to the quantity of seeds stored. Comparison of the four corvids suggests a pathway along which specialized seed‐caching corvids may have evolved. Zusammenfassung Für das Sammeln von Koniferensamen sind Kiefernhäher und Piñonhäher relativ hoch spezialisiert, Schwarzkopfhäher und Buschhäher relativ unspezialisiert. Die Spezialisation des Kiefernhähers und des Piñonhähers umfaßt Verhaltensweisen und Schnabelformen, die ein wirksames Einsammeln der Samen gestatten, morphologische Strukturen für den Transport der Samen, sowie Merkmale, welche die Kraft und Geschwindigkeit des Fluges erhöhen. Dank dieser Spezialisationen können Kiefernhäher und Piñonhäher mehr Samen über größere Entfernungen tragen als Schwarzkopfhäher und Buschhäher. Mit Hilfe eines einfachen mathematischen Modells wird untersucht, wie sich die gesamte Sammelzeit und die Strecke, über die die Samen transportiert werden, auf die Menge der versteckten Nahrung auswirken. Dieses Modell läßt außerdem drei Bereiche der Anpassung bei der Nahrungsuche erkennen: 1. die Wirksamkeit der Nahrungsuche, 2. die Menge der transportierten Samen und 3. die Flugfähigkeit. Der erste Bereich wirkt sich am stärksten auf die Menge der Samen aus, die in der Nähe des Verstecks gesammelt werden (Nutzung örtlicher Ressourcen). Die beiden anderen Bereiche gewinnen an Bedeutung, wenn die Entfernung zwischen Sammel‐ und Versteckgebiet wächst (Nutzung entfernter Ressourcen). Die abgestuften Anpassungen in Morphologie und Verhalten, die von diesen vier Rabenvogelarten verkörpert werden, deuten an, über welche Zwischenschritte die Evolution des Samenversteckens abgelaufen sein könnte. Nahrungsmangel zu bestimmten Jahreszeiten war sehr wahrscheinlich der entscheidende Faktor, der zu einem Selektionsdruck auf wirksames Sammeln und Anlegen von vorübergehend nutzbaren Ressourcen führte. Spezialisationen in Morphologie und Verhalten, welche die Nahrungssuche ergiebiger machten, ermöglichten, größere Samenvorräte anzulegen. Verstreut liegende Samenvorkommen waren vermutlich verantwortlich für die Evolution von Strukturen, mit deren Hilfe man Samen transportieren und so diese Vorkommen wirkungsvoll ausnutzen konnte. Das Anlegen der Verstecke wurde nach und nach verändert, einerseits um zu verhindern, daß Konkurrenten Vorräte stehlen, andererseits, um das Wiederfinden der Verstecke im Winter zu erleichtern. Während sich Anpassungen entwickelten, die es möglich machten, mehr und mehr Samen zu verstecken, gewannen diese versteckten Samen auch in anderer Hinsicht immer mehr an Bedeutung, insbesondere 1. als Nahrung für Erwachsene und Nestlinge, 2. für den frühen Beginn der Brutzeit und 3. für das häufige Auswandern der spezialisierten Arten. Vorfahren dieser Rabenvögel waren wahrscheinlich die Transportmittel, mit denen während de...

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Piñon seed assessment by the piñon jay, Gymnorhinus cyanocephalus

Cited by 36 publications

References 3 publications

Accuracy of memory for amount in the foraging starling,Sturnus vulgaris

Accuracy of memory for amount in the foraging starling,Sturnus vulgaris

Defense of Ripe Fruit from Pests: Its Significance in Relation to Plant-Disperser Interactions

Ecology and Evolution of Food-storage Behavior in Conifer-seed-caching Corvids

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