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Kacelnik, A., & Houston, A. I. (1984). Some effects of energy costs on foraging strategies. Anim. Behav., 32(2), 609–614.
Abstract: We consider the effect of including energy costs on the optimal strategy for animals exploiting a depleting food resource. In the context of central place foraging this leads to the problem of what load size should be brought back to the central place. Two strategies are discussed: (i) maximize gross rate of energy delivery and (ii) maximize net rate of energy delivery. The optimal load size (or optimal patch time) for net maximizers is not always larger than for gross maximizers, as has been claimed. Instead, the difference in optimal load size has the same sign as the difference between metabolic rates of travelling and foraging. We point out that the influence of costs has not always been correctly incorporated in experimental tests of the theory.
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McFarland, D. J. (1984). Roger L. Mellgren, Editor, Animal Cognition and Behavior, North-Holland, Amsterdam (1983), p. xi. Anim. Behav., 32(2), 634–635.
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Penzhorn, B. L. (1984). A Long-term Study of Social Organisation and Behaviour of Cape Mountain Zebras Equus zebra zebra. Z. Tierpsychol., 64(2), 97–146.
Abstract: Abstract and Summary 1. The social structure of Cape mountain zebras consists of breeding herds and bachelor groups. The breeding herds, which comprise 1 stallion, 1–5 mares and their offspring, remain stable over many years. When the stallion is displaced by another the mares usually remain together, although some herds split up. A dominance hierarchy exists, but leadership is not confined to the dominant member. Foals leave their maternal herds at a mean age of 21.9 months. The herd stallion tries to prevent foals from leaving the herd.2. Bachelor groups are not as rigidly structured as breeding herds but core groups could be identified through a Principal Components Analysis. Family ties may be important in the establishment of core groups. Bachelors succeed in becoming herd stallions when ca. 5 years old.3. The recipient of a threat moving away seems to be an adequate response. Submissive behaviour was only recorded in bachelors. Fighting is rare, with biting as an important element. Compared to plains zebras, sounds made in communication are limited. Social grooming mainly occurs between mare and foal. Grooming intention movements may be an appeasement gesture.4. An oestrus mare assumes a characteristic posture. Flehmen occurs. Urine and faeces of oestrus mares are often marked by the stallion. This cannot be explained functionally and is not restricted to eliminations of oestrus mares. Penis erection and jerking by resting stallions could serve as a warning signal, but may be masturbatory.5. The herd stallion actively herds members of his herd and reduces intraherd antagonism by means of threats. He usually leads when the herd goes to drink and brings up the rear when the herd moves away from danger.6. Play was rarely recorded.7. A challenge ritual is performed when herd stallions meet. When challenged by a herd stallion, a bachelor is submissive.8. Foals initially remain close to their mothers and have to learn the correct orientation when suckling. A single adoption was recorded.9. Individuals apparently recognise each other after long periods.10. Cape mountain zebras react to alarm signals of antelopes.11. The greater part of the day is devoted to grazing. A significantly greater percentage of the day is spent resting in winter than in summer. Cape mountain zebras mainly stand while resting, but resting in sternal or lateral recumbency also occurs. Defaecation and urination occurs throughout the day with no definite peaks.12. Grooming consists of localized muscle contractions, shaking, striking one part of the body against another or against the ground, rubbing, dust-bathing, scratching and nibbling.13. In cold weather, Cape mountain zebras seek shelter in wooded kloofs. Zusammenfassung * 1Bergzebras bilden Familien und Junggesellengruppen. Familien bestehen aus einem Hengst, 1–5 Stuten und deren Nachwuchs. Harems bleiben jahrelang unverändert. Wird der Hengst verdrängt, so bleiben die Stuten meist zusammen. Es besteht eine Rangordnung, doch führt nicht nur das dominante Tier. Fohlen verlassen die Familie mit durchschnittlich 21,9 Monaten. Der Familienhengst versucht, die Fohlen am Weggehen zu hindern. * 2Junggesellengruppen sind nicht so fest strukturiert wie die Familien, doch lassen sich Kerngruppen durch Hauptkomponentenanalyse identifizieren. Familienbeziehungen können für das Entstehen soldier Kerngruppen wichtig sein. Junggesellen können im Alter von ungefähr 5 Jahren Familienhengste werden. * 3Flucht ist offenbar die ausreichende Reaktion auf Drohung. Unterwürfiges Verhalten wurde nur bei Junggesellen beobachtet. Kämpfe sieht man selten. Bergzebras haben weniger Kommunikationslaute als Steppenzebras. Soziale Hautpflege findet meist zwischen Stute und Fohlen statt. PflegeIntentionsbewegungen können zur Streitschlichtung benutzt werden. * 4Rossige Stuten nehmen eine charakteristische Stellung ein. Flehmen kommt vor. Harn und Kot rossiger Stuten werden oft vom Hengst markiert. Erektion des Penis mit Zuckungen beim ruhenden Hengst kann entweder als Warnsignal oder als Masturbation gedeutet werden. * 5Der Hengst herdet die Mitglieder seiner Familie und bremst innerfamiliäre Aggression durch Drohen. Gewöhnlich führt er die Familie zur Tränke und verläßt als Letzter die Gefahrenzone. * 6Spielen wurde selten beobachtet. * 7Wenn Familienhengste sich treffen, findet ein Herausforderungs-Ritual statt. Junggesellen reagieren unterwürfig, wenn sie so herausgefordert werden. * 8Fohlen bleiben anfangs nahe bei der Mutter. Sie müssen die richtige Orientierung beim Säugen erlernen. Eine Adoption wurde registriert. * 9Individuen scheinen sich nach langer Zeit wiederzuerkennen. * 10Bergzebras reagieren auf die Alarmsignale von Antilopen. * 11Der größte Teil des Tages wird zum Grasen gebraucht. Im Winter gibt es signifikant längere Ruheperioden als im Sommer. Bergzebras ruhen meist stehend. Exkremente werden den ganzen Tag über ausgeschieden. Zur Körperpflege gehören örtliche Muskelkontraktionen, Schütteln, Schlagen eines Körperteils gegen einen anderen oder gegen den Boden, Reiben, Staubbaden, Kratzen und Knabbern. * 12Bei kaltem Wetter suchen Bergzebras in bewaldeten Schluchten Schutz.
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Sherry, D. F., & Galef Jr, B. G. (1984). Cultural transmission without imitation: Milk bottle opening by birds. Anim. Behav., 32(3), 937–938.
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Wolff, P. R., & Powell, A. J. (1984). Urine patterns in mice: An analysis of male/female counter-marking. Anim. Behav., 32(4), 1185–1191.
Abstract: Counter-marking in mice, Mus musculus was investigated by analysing urine deposition on filter paper marked asymmetrically with urine of the opposite sex. Intact males deposited large numbers of urine spots with a marked angular bias towards previously marked quadrants. More spots were deposited on proestrous and ovariectomized donor urine patterns, their distribution being more centrifugal on oestrous urine and more centripetal in quadrants containing a large female urine spot in a central position. In contrast, castrated male mice deposited very few spots with no angular bias. Female urine patterns showed angular bias in response to intact, but not castrated male donor urine, a larger number of spots being produced by oestrous females. Thus the pattern of deposition offers scope for two-way communication of information about reproductive potential.
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Keiper, R., & Houpt, K. (1984). Reproduction in feral horses: an eight-year study. Am J Vet Res, 45(5), 991–995.
Abstract: The reproductive rate and foal survival of the free-ranging ponies on Assateague Island National Seashore were studied for 8 years, 1975 to 1982. Most (52%) of the 86 foals were born in May, 13% were born in April, 22.6% in June, 10.4% in July, and less than 1% in August and September. The mean foaling rate was 57.1 +/- 3.9% and the survival rate was 88.3 +/- 3.6%. Forty-eight colts and 55 fillies were born (sex ratio 53% female). Mares less than 3 years old did not foal and the foaling rate of 3-year-old mares was only 23%, that of 4-year-old mares was 46%, that of 5-year-old mares was 53%, and 6-year-old mares was 69%. The relatively poor reproduction rate was believed to be a consequence of the stress of lactating while carrying a foal when forage quality on the island was low. The hypothesis was supported by the higher reproductive rate (74.4 +/- 2.4%) of the ponies in the Chincoteague National Wildlife Refuge on the southern part of the island. Their foals are weaned and sold in July each year. Despite the low reproductive rate on Assateague Island National Seashore , the number of ponies increased from 43 to 80, a 90% increase in the 8-year period or greater than 10%/yr. There were 24 deaths and 8 dispersals from the study area.
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Seyfarth, R. M., & Cheney, D. L. (1984). The acoustic features of vervet monkey grunts. J Acoust Soc Am, 75(5), 1623–1628.
Abstract: East African vervet monkeys give short (125 ms), harsh-sounding grunts to each other in a variety of social situations: when approaching a dominant or subordinate member of their group, when moving into a new area of their range, or upon seeing another group. Although all these vocalizations sound similar to humans, field playback experiments have shown that the monkeys distinguish at least four different calls. Acoustic analysis reveals that grunts have an aperiodic F0, at roughly 240 Hz. Most grunts exhibit a spectral peak close to this irregular F0. Grunts may also contain a second, rising or falling frequency peak, between 550 and 900 Hz. The location and changes in these two frequency peaks are the cues most likely to be used by vervets when distinguishing different grunt types.
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Ralston, S. L. (1984). Controls of feeding in horses. J. Anim Sci., 59(5), 1354–1361.
Abstract: Members of the genus Equus are large, nonruminant herbivores. These animals utilize the products of both enzymatic digestion in the small intestine and bacterial fermentation (volatile fatty acids) in the cecum and large colon as sources of metabolizable energy. Equine animals rely primarily upon oropharyngeal and external stimuli to control the size and duration of an isolated meal. Meal frequency, however, is regulated by stimuli generated by the presence and (or) absorption of nutrients (sugars, fatty acids, protein) in both the large and small intestine plus metabolic cues reflecting body energy stores. The control of feeding in this species reflects its evolutionary development in an environment which selected for consumption of small, frequent meals of a variety of forages.
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Dunbar, K., & MacLeod, C. M. (1984). A horse race of a different color: Stroop interference patterns with transformed words. J Exp Psychol Hum Percept Perform, 10(5), 622–639.
Abstract: Four experiments investigated Stroop interference using geometrically transformed words. Over experiments, reading was made increasingly difficult by manipulating orientation uncertainty and the number of noncolor words. As a consequence, time to read color words aloud increased dramatically. Yet, even when reading a color word was considerably slower than naming the color of ink in which the word was printed, Stroop interference persisted virtually unaltered. This result is incompatible with the simple horse race model widely used to explain color-word interference. When reading became extremely slow, a reversed Stroop effect--interference in reading the word due to an incongruent ink color--appeared for one transformation together with the standard Stroop interference. Whether or not the concept of automaticity is invoked, relative speed of processing the word versus the color does not provide an adequate overall explanation of the Stroop phenomenon.
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Seyfarth, R. M., & Cheney, D. L. (1984). Grooming, alliances and reciprocal altruism in vervet monkeys. Nature, 308(5959), 541–543.
Abstract: Reciprocal altruism refers to the exchange of beneficial acts between individuals, in which the benefits to the recipient exceed the cost to the altruist. Theory predicts that cooperation among unrelated animals can occur whenever individuals encounter each other regularly and are capable of adjusting their cooperative behaviour according to experience. Although the potential for reciprocal altruism exists in many animal societies, most interactions occur between closely related individuals, and examples of reciprocity among non-kin are rare. The field experiments on vervet monkeys which we present here demonstrate that grooming between unrelated individuals increases the probability that they will subsequently attend to each others' solicitations for aid. Vervets appear to be more willing to aid unrelated individuals if those individuals have behaved affinitively toward them in the recent past. In contrast, recent grooming between close genetic relatives appears to have no effect on their willingness to respond to each other's solicitations for aid.
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