bluuebunny/crossref_metadata_2025 huggingface dataset:
Host Selection as an Adaptation To Host-Dependent Foraging Success in the Cattle Egret (Bubulcus Ibis)
Authors: Burger Joanna , Gochfeld Michael
Published: April 2008

In southern Africa, the commensal foraging cattle egret has a wide variety of potential ungulate species from which to select its hosts. We found that the preferred hosts involved just a few of the available species. We predicted that ultimately the selection of hosts should be adapted to maximize egret foraging success. Selection is hierarchical with birds first choosing a general area in which one or more host species may be present. They then choose a host herd, and finally select an individual which they accompany as long as its actions are suitable and prey items are disturbed. The decision process remains flexible. Egrets freely switch hosts moving from one cow or wildebeest to another. We found the predicted correlation between egret and host walking rate (steps/min.), and also that feeding success was related to number of egret steps. We looked for evidence that egrets would select species and individuals that allowed them to move at the optimum rate for foraging. We found egrets achieving maximum success at walking rates between 10 and 30 steps per minute. When hosts moved more slowly or more quickly, feeding success was low, and egrets switched hosts more frequently. We censused wild animals in game parks and domestic animals on farms, and found a similar overall abundance (individuals/km). Wild animal herds provided fewer suitable hosts (individuals moving at the optimal rate for the egrets). We conclude that there are three components to host selection. Hosts must be available in adequate numbers and must be easy to locate. They must be suitable in terms of providing egrets with good foraging situations. They must be reliable in terms of remaining in the same general area day after day and in terms of consistent rates of locomotion. Although wildebeest, zebras, and buffalo fit one or two of the criteria, cattle fulfill all three. We speculate that the widespread increase in cattle farming in the past century may have facilitated the world wide population explosion of the cattle egret.
The Coevolution of Receptivity Signalling and Body-Size Dimorphism in the Chalcidoidea
Authors: Van Den Assem J. , Jachmann F.
Published: April 2008

In the Chalcidoidea (small hymenopterous parasites of the developmental stages of many kinds of insects) two evolutionary trends can be traced: reduction of male size, and switch of the courtship position of the male relative to the female from rear to front. The positional shift is related to the development of antennal movements produced by the female at the onset of sexual receptivity. The signal function of these movements was shown with experiments including the use of dummies. The experimental results are discussed in relation to selective pressures shaping courtship and mating behaviour in the Chalcidoidea.
Effects of Species-Specific Vocalizations On the Behaviour of Surrogate-Reared Squirrel Monkeys
Authors: Herzog Michael , Hopf Sigrid
Published: April 2008

This is a contribution to the study of the communicative behaviour in a primate, the squirrel monkey (Saimin). It will be shown whether socially inexperienced infants respond differentially to species-specific vocalizations. Six squirrel monkeys were separated from their mothers and conspecifics on the day of birth and surrogate-reared up to their 3rd month of age. In order to counteract general deprivation effects, the subjects received visual, auditory and vestibular stimulation, in addition to the constant presence of the mother surrogate and manipulanda. From the 2nd week on subjects were presented a test object 3-6 times daily. The object was so designed as to elicit behaviour which would usually be directed to conspecifics. When the subjects were able to locomote freely in their cage and approach the object on their own, the following experiment was carried out: Upon each physical contact by the subject with the object, a sound was played back by a loudspeaker hidden in the object. During any 8-min. session only one of five preselected sounds was used. The effect of two vocalizations, caw and cackle, known to be aversive in squirrel monkey groups, was compared to that of two non-aversive ones, twitter and play peep, and a neutral control tone. Caw and cackle resulted in low overall contact and less varied and less playful activities toward the test object. Subjects also were facing the objects more from a distance and spent more time in contact with the mother surrogate as their security figure. Twitter and play peep resulted in an opposite pattern. These findings indicate a genetically preprogrammed basis for perception and processing of species-specific vocalizations.
Quatic Foraging in Garter Snakes: a Comparison of Specialists and Generalists
Authors: Drummond Hugh
Published: April 2008

To examine the assumption, underlying much ecological theory, that a "Jack-of-all-trades is master of none", a comparison was made of the aquatic predation of four colubrid snakes, two aquatic specialists (Thamnophis couchi, T. melanogaster) and two terrestrial-aquatic generalists (T. sirtalis, and T. elegans). Observations were made in the field, then juvenile snakes were compared under controlled laboratory conditions. The specialists and generalists had qualitatively different foraging repertoires. The specialists made lengthy dives, crawled slowly on the underwater substrate and made long-distance underwater responses to prey: orientation, approach, pursuit, and frontal attack. The generalists dived briefly, with rapid serpentine locomotion, or searched "terrestrially" by wandering along the shoreline and snatching prey from the water surface. Underwater, the generalists' only prey-directed response was sudden short-distance attack, and they appeared to rely on chance encounters with prey. There were significant differences between the two pairs. In comparison with the generalists, the specialists 1) captured more fish, 2) spent more time on aquatic search, 3) spent more aquatic search time diving, 4) spent more diving time on the underwater substrate, 5) made more attacks in every category of search in open water, and 6) attacked underwater from a greater distance. Significant differences were not found in attack frequencies in those search categories where underwater vision is probably unimportant (aerial attacks and attacks in underwater crevices), nor in aerial attack distances. The specialists' behavioral superiority in respect of their specialization supports the "Jack-of-all-trades" assumption. The observations suggest that this superiority is associated with superior underwater visual acuity (which may be due to superior visual accommodation). The generalists' principal underwater searching technique (serpentine diving) appears to be energetically costly, and may only be profitable when aquatic prey are especially vulnerable. Nerodia sipedon, member of a genus that is closely related to Thamnophis but more aquatic, had a foraging repertoire qualitatively similar to that of the generalists. The similarity may be associated with N. sipedon's nocturnal habits and presumed reliance on non-visual prey cues.
A Factor Analysis of Seasonal, Behavioral, Hormonal and Body Weight Changes in Adult Male Barheaded Geese, Anser Indicus
Authors: Dittami John P. , Reyer Heinz-Ullrich
Published: April 2008

Individual measurements of courting, aggression, pairbond displays, body weights and the circulating levels of testosterone, LH, T4 and prolactin in male barheaded geese were subjected to a factoral analysis. Data from the whole year were analysed and then broken up into pre-breeding and post-breeding components and re-analysed. Some parameters remained clumped in the same factors throughout like aggression and pair-bond displays, LH and testosterone, and prolactin and body weight. Others, especially behavioral and endocrinological parameters were only linked on either an annual or seasonal basis.
Sex Roles in the American Oystercatcher
Authors: Nol Erica
Published: April 2008

American oystercatchers have extensive parental care. As a result sex roles are similar and highly complementary. During the pre-laying period the roles of males and females, except during copulation, are indistinguishable. During the laying period the roles diverge slightly with males spending more time chasing conspecifics. Presumably the similarity during pre-laying, and the differences during laying, function to prevent the male from being cuckolded. Males begin assisting in incubation as soon as the females begin incubating and then consistently perform the same proportion of incubation throughout this breeding stage. During incubation, females incubate more often than males, and consequently rest less, preen less and fly less than males. During chick-rearing males are involved in more chases than females and take more foraging trips to provision young but wait longer between successive trips. The pattern of foraging by each sex is complementary. Breeding season energy expenditure is approximately equal in both sexes. There is no evidence for conflict between the sexes over the contributions to parental care. Where sex roles diverge the differences in behaviour can be partly explained by the relative energetic efficiencies of each sex performing different tasks.
Acoustic Communication and Mating Behaviour in the Muellerianella Complex (Homoptera - Delphacidae)
Authors: Drosopoulos S.
Published: April 2008

Some data on acoustic communication and mating behavior of two biparentally reproducing species and the clonally reproducing pseudogamous "species" of the genus Muellerianella are reported. Although bioacoustic differences were found in the calling songs between the species, these did not prevent pairforming. Also, differences in mating behavior, such as pre-copulation behavior, courtship activities, frequency and duration of copulation were not sufficient to prevent successful hybridization between both the two biparentally reproducing species and between each of these two species and the pseudogamous "species". The data reported here are related to other biological differences reported previously. According to these data there is some evidence that differences in acoustic communication and mating behavior between the two species are established by ecological influences which in turn have established analogous physiological requirements. These differences are rather weak isolating mechanisms. Regarding the behavioral relation of the pseudogamous species with males of the two parental species it was found that these females behave exactly as the females of M. fairmairei with which they coexist in the field. In interspecific crosses mechanical barriers to copulation are more efficient than courtship differences. Finally it is assumed that pseudogamy is a strong isolation mechanism between the not yet fully genetically differentiated bisexual species of Muellerianella.
Semantics of an Avian Alarm Call System: the Male Domestic Fowl, Gallus Domesticus
Authors: Marler Peter , Pickert Roberta , Gyger Marcel
Published: April 2008

Vocal alarm signals of male domestic fowl given in the presence of predators and other ground and aerial objects were recorded and analyzed. Studies were conducted under semi-naturalistic conditions and a telemetric technique was used to facilitate high quality sound recording. Cockerels gave ground alarm calls specifically to objects moving on the substrate and aerial alarm calls to objects moving above in free space. Vocalizations were associated with both dangerous and harmless objects. We therefore investigated variation in sound structure of aerial alarm calls with reference to flying predators and non-predators. A multidimensional contingency table analysis revealed a significant tendency for qualitatively different aerial alarm calls to be associated with flying predators and non-predators. Differences in call structure were restricted to the two first units of the alarm call. We tested the hypotheses that variation in aerial alarm call structure might be affected by either the distance separating the bird from the object or the angular size of the object projected onto the retina of the cockerel. Statistical analysis showed that the angular size was a good predictor of variation of the second unit of alarm call. The distance it self was less predictive. The first unit of the alarm call was not affected by either the distance or the angular size of the object. We propose that this part of the call has a more general function of alerting the conspecific companions. We conclude that alarm vocalizations of male domestic fowl refer specifically to a certain type of stimulus object, either moving on the ground or flying. For alarm calls correlated with aerial stimuli the specific angular size of a stimulus object moving in the air is a good predictor of call structure. We suggest that this way of dealing with flying objects as stimuli for alarm calls is the result of a predator detection strategy in which the benefits of an expanded field of vision, an important adaptation for ground-dwelling birds, exceed the costs of alarming to harmless birds and other aerial objects.
Song Learning in Cross-Fostered Zebra Finches: a Re-Examination of the Sensitive Phase
Authors: Clayton N.S.
Published: April 2008

Male zebra finches, Taeniopygia guttata, which have been normally-raised or cross-fostered to Bengalese finches, Lonchura striata, learn from a song tutor with whom they arc housed during the sensitive phase, between 35 to 70 days of age. If the tutor is a different species from the father or foster-father however, then the tendency to learn during this time is much less and some males will produce song heard before 35 days. None of the birds in this study learnt after 70 days, although some lost song elements or added improvised ones. These results suggests that specific types of experience influence when a young bird learns its song. It seems that exposure to "poor" song during the sensitive phase stimulates the bird to remember song heard previously and blocks further learning after this time. These results are compared with those obtained in imprinting studies.
Temporal and Spatial Differences in Traditions and Repertoires in the Song of the Thrush Nightingale (Luscinia Luscinia)
Authors: Sorjonen Jorma
Published: April 2008

Differences in the song repertoires of males and in the song-pools of the thrush nightingale populations were studied in 1972, 1983 and 1984 in southern Finland. Changes in male repertoires and in the song-pool of one population were monitored in 1972 and 1980-1985. The thrush nightingales in a local population had repertoires that were more similar to each other than to those of the males in other local populations. The similarity of the repertoires decreased with increasing distance, but there were no clear-cut dialect boundaries between local populations. The song repertoire of a male was more similar to that of the adjacent males than to his own repertoire of the previous year. The similarity of the repertoires of adjacent singers increased during the singing period. This similarity was partly due to the same song-types being used with about equal frequency, but obviously the males were also able to learn new songs from their adjacent singers. After dispersal to a breeding area thrush nightingales learn at least some new song-types, even at the age of two to four years. Some old breeders were able to copy new song-types from the immigrants (mostly young males) or the playback tape. The newly copied song-types were loud and simple in structure, whereas the song-types soon to be abandoned were weak in amplitude. In one population, studied from 1980 to 1985, the repertoires of the males tended to become more similar in successive years. This tendency, however, did not occur in 1984 when the proportion of immigrants in the population was unusually high. The major changes in local song traditions were due to "cultural diffusion" by males originating from areas with other traditions; this diffusion greatly enriched the local song-pool, especially in years when the rate of immigration was high.
Cross-Fostering, Imprinting and Learning in Two Sympatric Species of Cockatoo
Authors: Chapman Graeme , Rowley Ian
Published: April 2008

Two species of cockatoo, the galah Cacatua roseicapilla and Major Mitchell's cockatoo C. leadbeateri are sympatric throughout much of Australia. Both species nest in tree-hollows of similar dimensions at the same time of year. Their eggs which are very similar are laid every other day and are not incubated until at least three have been produced. Parent birds often forage a long way from the nest and so the early eggs are largely unattended. Sometimes a pair of C. roseicapilla and one of C. leadbeateri both "own" the same hollow and contribute eggs to the clutch. When confrontation finally arises the C. roseicapilla being smaller, lose out and the C. leadbeateri unknowingly incubate a mixed parentage clutch, and may rear a young C. roseicapilla with their own offspring. Such cross-fostered C. roseicapilla behave as, and associate with C. leadbeateri; they ignore other C. roseicapilla. Parts of their behaviour repertoire are innate, parts are the result of imprinting and parts, of later learning. They learn to fly and to call like C. leadbeateri and they also adopt the latter's much more varied diet. Cross-fostered C. roseicapilla are probably responsible for those cases of hybridisation in the wild between C. roseicapilla and C. leadbeateri that have been reported.
Different Functions of "Alarm" Calling for Different Time Scales: a Preliminary Report On Ground Squirrels
Authors: Owings Donald H. , Gladney A. Beckett , Hennessy David F. , Leger Daniel W.
Published: April 2008

The predator-evoked calling of California ground squirrels (Spermophilus beecheyi) was studied in the field during the reproductive season. Three different sources of data indicated that adults call more after, than before their young have reached the age of first emergence from natal burrows. During exposure to a tethered rattlesnake (Crotalus viridis oreganus) and to a freely-moving dog (Canis familiaris), and in natural encounters with a coyote (Canis latrans) or bobcat (Lynx rufus), calling was more frequent after than before young first emerged. We concluded that California ground squirrels call in order to warn their offspring about predators, like other ground squirrel species do. In order to see the increase in mammalian predator evoked calling after pup emergence, we had to separate calling on the basis of its temporal organization. Nonrepetitive calling involved spacing a few vocalizations irregularly in time. Calls patterned in this way were more common early in an encounter, became more frequent after pup emergence, and more consistently elicited immediate reactions. Such calling was probably used to warn pups. Repetitive calling comprised rhythmic emission of a series of vocalizations. Calls organized repetitively were more common later in an encounter, were not emitted more frequently after pup emergence, and less consistently evoked immediate reactions. These and other differences between the two temporal patterns of vocalizing led us to propose that repetitive calling represented a "tonic" communicatory effort (as in SCHLEIDT, 1973). Repetitive inputs to other squirrels may act "cumulatively" in a longer time scale than nonrepetitive calling, so as to cultivate or maintain vigilance in other squirrels. The repetitive caller could benefit by using the enhanced reactions of these more vigilant squirrels as a source of information about the predator. We propose that predator-prey episodes may be understandable from an "epigenetic" perspective. That is, the first alarm calls during an encounter should shift squirrels from an unwarned to a warned status; subsequent calling must then function in some other way than as a warning.
Developmental Changes in the Caravaning Behaviour of the House Musk Shrew (Suncus Murinus)
Authors: Ishikawa Tomohiko , Matsuo Takashi , Tsuji Kechiro
Published: April 2008

Development of caravaning behaviour in the house musk shrew (Suncus murinus) was described in detail and discussed in relation to sensory and motor development. With age of pups, caravaning changed in its formation pattern (I-V) as well as its quantitative aspects such as frequency of occurrence, duration and distance. The shift in formation pattern from II to III was simultaneous with the onset of vision (Experiment I). In darkness, frequency of caravaning significantly decreased at ages later than 11 days. This was due to the selective disappearance of Patterns III and V (Experiment II). These findings suggest the role of vision in caravan formation at the later stage of the period of occurrence. After the onset of vision, caravaning is released mostly by visual motion of the object, whereas caravaning at the earlier stage is released nonvisually. Caravaning and the pup's locomotor activity were suppressed and delayed until the age of weaning in the enclosure set up to simulate the natural habitat. The period of occurrence was reduced by disappearance of some formation patterns observable in the laboratory open-field and the onset of caravaning exactly synchronized with that of spontaneous and independent locomotion. Development of caravaning in the outdoor enclosure closely resembled the development of Pattern V in the open-field (Experiment III). The adaptive significance of caravaning can be fully understood only by comparing behaviours which occur in different situations. Such an approach could bridge the gap between observations in the laboratory and those in the natural habitat. In Experiment I, caravaning was compared between domesticated laboratory animals and animals at the first two generations of nonsib-mating from wild ones. The age-dependent tendency was more distinct in the latter group. This suggests that mother-offspring relations changed in the process of domestication.
Temporal Organisation in the Behaviour of Newborn Infants in Active Sleep
Authors: Briem Valdimar
Published: April 2008

The human neonate normally spends nearly 2/3 of its time asleep, and of this time ca 2/3 are spent in active sleep (AS). The present study was designed to investigate the temporal organisation and behavioural composition of this state. The hypothesis was put forward that the amount of facial behaviour that could be observed at any point in time during AS was representative of the neonate's general state of activation, and that the degree of activation varied with cyclic regularity. To test this, the facial behaviour of 8 normal neonates was filmed, and the films observed repeatedly. All activity occurring in three facial regions was registered and the resultant behavioural sequences analysed. It was found that facial behaviour tended to occur in bursts, and the median activity-quiescence cycle length was about 9 seconds. The amount of facial behaviour tended to wax and wane in a compound rhythm, and the lengths of the activity cycles involved could be predicted from a geometric function model. The results were compared with the evidence for cyclic behavioural activity found by previous investigators, and several explanatory models were examined. It is proposed that the activity cycles observed here are related to the rhythmicity observed in other behavioural states of the human infant.
Comment Le Chant Du Troglodyte (Troglodytes Troglodytes) Émerge Du Bruit
Authors: Brémond Jean-Claude , Kreutzer Michel
Published: April 2008

The information theory tells us which strategies can be used to compensate for alterations introduced by the channel. By encoding, the wren constructs his song in such a way that it can take advantage of most of these strategies. By decoding, it does not use all the strategies which encoding has made available. The choise and number of those which are used is a function of difficulties which the bird will encounter in recognizing the song of its own species. For instance, the duration or even the existence of silences between the notes are not taken into account. The bird uses them only to remove a difficulty about elements recognition. In this manner it is possible to explain the effectiveness and reliability of song as a means of communication.
Aggressive Behaviour Between Territorial Cichlids (Astatotilapia Burtoni) in Relation To Rank and Territorial Stability
Authors: Fernö Anders
Published: April 2008

Territorial mosaics of A. burtoni were studied in the laboratory. A difference in rank between neighbouring territorial fish was usually found, with the male with higher rank exhibiting more offensive behaviour and the opponent resisting more passively. A role asymmetry in boundary disputes was found in both high- and low-intensity aggression. Linear rank orders were formed. High rank was associated with a high aggressive and sexual activity towards non-territorial fish and a high mating succes". Territorial size was larger in superior males. A superior did not, however, generally expand his territory towards an inferior. This could be due to the involvement of escalated aggression with the reduction of territory. Most males of low rank did, however, eventually lose their territories. Establishing and losing territories were correlated with a low level of low-intensity aggression. Escalated fighting seldom occurred in spite of a strong competition for females, and aggression was usually limited to Frontal display and low-intensity aggression. Frontal display also played a key role for de-escalation of physical aggression. A. burtoni seems to follow the strategy "Honest", using a honestly graded display with few escalations.
Extra-Pair Copulations and Mate Guarding in the Polyterritorial Pied Flycatcher, Ficedula Hypoleuca
Authors: Lundberg Arne , Gottlander Karin , Alatalo Rauno V.
Published: April 2008

1. Seven out of 24 observed copulations (= 29% ) in the pied flycatcher were extra-pair copulations (EPCs). There was no significant difference between EPCs and pair copulations (PCs) with respect to timing and duration, possibly indicating that both are equally successful. Thus, proportion of copulations may reflect share of paternity. 2. Females usually do not solicit EPCs and often try to avoid them. We cannot find that females have much to gain from EPCs, while attempts to resist forced copulations may impose some costs. The fact that EPCs still are rather frequent suggests that it might be cheaper for a female to accept an EPC than to resist it. 3. Males spend much of their time mate guarding but the distance between pair members is longer for polyterritorial males than for monoterritorial males. Still, we cannot find any significant differences in risks or possibilities of EPCs between males of different mating status. However, the relaxed mate guarding by polyterritorial males suggests that these males might take higher risks, and they also suffer more territory intrusions. 4. It is most likely that male reproductive strategies are not maintained as a frequency-dependent mixed ESS with equal pay-offs for all paired males. Instead, male strategies are conditional on phenotype and breeding circumstances.
The Effects of Parent and Offspring Gender On Food Allocation in Budgerigars
Authors: Stamps Judy , Clark Anne , Kus Barbara , Arrowood Pat
Published: April 2008

Parental feeding rates in relation to the sex of parents and offspring were studied in domesticated budgerigars in large flight cages at Davis, California. While neither the male nor the female parent preferentially fed offspring of either sex, paternal feeding rates were strongly related to the sex ratio of the brood. Fathers fed female-biased broods much more frequently than male-biased broods throughout the nest cycle, and male feeding rates were highly correlated with the sex ratios of the broods. Mothers exhibited a similar but much weaker tendency to feed female-biased broods more often, and only at the end of the nest cycle was there a barely significant relationship between sex bias and maternal feeding rate. As a result of the extra parental care, female-biased broods obtained nearly three times more regurgitations in the final pre-fledge period than male-biased broods. Brood sex ratios were unrelated to fledge weights, and male and female nestlings fledged at comparable weights. However, for all but the smallest broods, there was a strong negative relationship between the percent of females within the brood and the average age of fledging. Fledge age, in turn, was related to post-fledge activity rates. Females fledging at younger ages initiated more flights than those fledging at older ages. Conversely, in males, fledge age was either unrelated, or positively related to the rate of flights. There were also significant negative relationships between female fledge age and reproductive success (e.g. number of young fledged in the first breeding season), but no significant relationships between male fledge age and reproductive success. Hence, male parents may provide extra care to broods biased toward the offspring sex which most benefits from this extra care.
Selection for Larval Vagility in Drosophila Melanogaster
Authors: Katz Mary , Levine Louis , Rockwell Robert F.
Published: April 2008

Six lines of the Drosophila melanogaster Oregon-R stock were established and each line was selected for either slow or fast larval movement through a system that consisted of single, double, or triple rings. Selection was successful in all three "slow lines" but not in any of the "fast lines". A test for movement of the adults from each of the six lines failed to reveal any correlated response. It is concluded that larval vagility in this stock is close to the maximum possible, and that there is no common genetic control over the tested types of movement in the two active stages of the organism's life cycle.
Intraspecific Variation in Extra-Pair Copulation and Mate Defence in Common Guillemots Uria Aalge
Authors: Hatchwell B.J.
Published: April 2008

Extra-pair copulation (EPC) in common guillemots was frequent during the pre-laying period. Although guillemots are essentially monogamous, males adopted a mixed reproductive strategy (MRS) by attempting to obtain forced extra-pair copulations (FEPC) during the female's fertile period, which was estimated to start 25 days prior to laying. Males spent more time at the colony than females and exhibited highly synchronized cycles of attendance during the pre-laying period in order to defend their partner against EPC attempts. By doing so they probably incurred some energetic cost. Pair copulation started as soon as the adults returned to the colony (4-5 months before the start of egg-laying), when it probably serves a pair-bonding function. From about 25 days before egg-laying (day -25) the PC rate increased, peaking at about day -12. It was estimated that guillemots copulated 22 times in the three weeks prior to egg-laying. The FEPC rate increased towards egg-laying and was more closely correlated with date than with the relative number of males present, although the number of males involved in each FEPC attempt increased towards laying. During the fertile period, 10% of all observed copulation attempts were FEPCs. However, the success rate (the proportion achieving cloacal contact) of FEPCs was much lower (6%) than that of PCs (74%). Females also employed an MRS, occasionally soliciting or co-operating in unforced extra-pair copulations (UEPCs) when their male partner was absent from the colony. UEPCs were much more successful (95%) than FEPCs, but also less frequent. The effect of breeding density on copulation behaviour was examined. FEPCs were more frequent at high breeding densities than at low density. The probability of obtaining FEPC insemination for males with two or more neighbours was about ten times that of males with no neighbours. Similarly, the risk of cuckoldry increased with density. increased with density. Three hypotheses were considered concerning the effect of density on the PC rate: the 'dilution' hypothesis predicted a higher PC rate at high density, and the 'disguise' and 'interference' hypotheses predicted a lower PC rate at high breeding density. The PC rate decreased with increasing density as a result of disruption of PCs by neighbouring males attempting to obtain FEPCs, a result consistent with the 'interference' hypothesis. The reproductive success of males obtaining EPCs, cuckolded males, and non-EPC/non-cuckold males was examined, and a selective advantage of 10% estimated for successful EPC males over cuckolds.
Patch Use and Patch Depletion By the Spider and Howling Monkeys of Santa Rosa National Park, Costa Rica
Authors: Chapman Colin
Published: April 2008

Patch depletion is an assumption that underlies many behavioural ecological models, yet it has rarely been examined. The evidence presented here suggests that the spider and howling monkeys of Santa Rosa National Park, Costa Rica use food resources that occur in patches and generally deplete the patches they use. However, some types of patches (e.g. large fruiting trees for spider monkeys, and trees used as sources of leaves for howlers) are not depleted by the feeding activity of primates. An examination of which types of patches are depleted and the manner in which depletion likely occurs, allows an assessment of possible factors underlying the different types of social organizations in these species.
Influences On the Choice Between Territorial and Satellite Behaviour in Male Libellula Quadrimaculata Linn. (Odonata: Libellulidae)
Authors: Convey Peter
Published: April 2008

Territorial behaviour of male Libellula quadrimaculata Linn. was investigated at Wicken Fen, Cambridgeshire, in 1986. Males were intensely territorial, expelling any other males that flew into their territory. Territories were defended for the mating opportunities that they provided. As local population density increased a number of males adopted satellite behaviour, although most continued to behave territorially. Wingspan and hindwing length were significantly larger in satellites than in territorial males. The likelihood of satellite behaviour was not related to male age. There was also no difference in age between satellite-host pairs in which both individuals were of known age. Satellite males were not observed to mate successfully, though they did not suffer the costs associated with territorial defence. A series of removal experiments demonstrated that the satellites could take over a territory and behave aggressively to other males. Scaling factors may have an important function in forcing larger males to adopt the less successful satellite role. Notably, flight muscle content was lower than expected in larger individuals, which should result in lower power output per unit body weight, and thus lower maximum acceleration and manoeuverability.
Assessments and Decisions During Mate Choice in Gammarus Pulex (Amphipoda)
Authors: Dick Jaimie T.A. , Elwood Robert W.
Published: April 2008

Male Gammarus pulex preferentially enter precopulatory mate guarding with large females close to moulting. The interactions of males and females were observed in an attempt to elucidate the process by which males assess females and, further, to determine how such information gathering influences mating decisions. Males which encountered single females, which had recently been experimentally separated from other males, grabbed and held those females in a perpendicular hold prior to establishing the precopulatory hold. The higher the reproductive quality of the female the more rapid was the male decision to move into the perpendicular hold but this was followed by an increased level of abdomen flexing and antennae touching. Once precopula was established, higher quality females received more stroking with the free gnathopods. When two females were encountered, some males simply took the first contacted and this resulted in random pairing. Other males, however, demonstrated the ability to sequentially sample as well as simultaneously compare females and, if this occurred, they almost invariably took the higher quality female. Discrimination between two females was more rapid as the difference in their qualities increased whereas males engaged in more grabbing and holding when females were of similar moult stages. The data show that assessment of female size and moult stage occurs early in the interaction, whereas subsequent activities such as flexing and stroking are probably involved in courtship, possibly serving to pacify females.
Ontogeny of Ultrasonic Vocalizations in the Woodmouse (Apodemus Sylvaticus L.). I: Temporal Organization
Authors: Pontet André , Gyger Marcel , Schenk Francoise
Published: April 2008

We have studied the ontogeny of ultrasonic vocalizations in the woodmouse, Apodemus sylvaticus, a high vocalizing palearctic murid species. Vocalization and behaviour were recorded as the pups were daily isolated for three minutes at ambiant temperature in two different experimental conditions: a plus-maze and a cup. The temporal organization of the vocalizations was analysed using log survivor functions of the intervals between the calls. These functions provided a reliable bout criterion indicating that ultrasound production by the youngest pups was clustered in bouts. Ontogenetic changes in the ultrasound production appeared different when measured in calls or in bouts per time unit. The call rate decreases from PND 11 onwards, whereas the bout rate remains elevated up to PND 15. Ultrasound production and locomotor activity arc associated from PND 11 onwards. The high ultrasound production by two-week old pups in the plus-maze is related to a very high locomotor activity in this experimental condition. We have identified four different steps in the ontogeny of ultrasonic vocalisations in the woodmouse: 1) Just after birth, the pups emit very few ultrasounds. 2) Around PND 3, there is a tremendous vocal output: the pups vocalize in a tonic mode, almost continuously. 3) The tonic mode goes gradually into a phasic mode in which ultrasounds are clustered in bouts; the total production decreases as the pups grow up. From PND 11 onward, most of the calls are produced during locomotion. 4) Around PND 15 there are mainly single calls, like in the adults. The very intense and frequent calls emitted during the second step are known to be distress calls. Since their production is accompanied by a high muscular activity, that might also delay cooling of the pups. The calls emitted by two-week old pups might serve as contact calls increasing the cohesion between the pups at the time of the first excursions out of the nest. In this way, these calls might diminish the predation risk and would facilitate a possible protection or retrieval by the mother.
Dangerous Lions and Nonchalant Buffalo
Authors: Prins H.H.T. , Iason G.R.
Published: April 2008

1. Aspects of the influence of predation on the African buffalo Syncerus caffer were studied in Lake Manyara National Park, northern Tanzania, from 1981 to 1985. 2. During the study period, predation by lions was the most important cause of death in buffalo but occasionally major epidemics, such as rinderpest, can be by far the most important cause of death. 3. A comparison of Manyara with four other areas in Africa shows that the Manyara buffalo ran the same level of risk as those in these other areas, and that in periods in which epidemics or drought conditions are absent it was normal that ultimately some 90% of the large herbivores fell victim to predation. 4. Juvenile mortality in females was higher than in males but adult mortality in females was lower than in males. Adult bulls ran a much higher risk to be killed by lions (12.9% p.a.) than herd-living buffalo (4.4% p.a.); the latter category comprised cows and sub-adult bulls. 5. Risk of predation was highest near the ecotone between grasslands and structurally closed vegetations. Grasslands were as dangerous as woodlands and thickets, and only the mudflats were really safe. The chance to be killed fell steeply away from (potential) cover for lions. 6. Buffalo were more vigilant at night than during the day, peripheral animals more so than central ones. Adult bulls were more vigilant than other categories of buffalo. It is concluded that vigilance in buffalo was not restricted to predator detection. 7. The choice of feeding areas in buffalo was not dictated by predation risk alone.
Adaptive Superparasitism and Patch Time Allocation in Solitary Parasitoids: the Influence of the Number of Parasitoids Depleting a Patch
Authors: Visser Marcel E. , VAN ALPHEN Jacques J.M. , Nell Henk W.
Published: April 2008

An ESS model that predicts more superparasitism and longer patch times with an increasing number of searching parasitoids in a patch, was tested in experiments with Leptopilina heterotoma, a solitary larval parasitoid of Drosophila. The observed egg distributions and patch times were in quantitative agreement with the predictions of the model; oviposition and patch time decisions are clearly influenced by the number of conspecifics in the patch. Both in the model and in the experiment patch quality was kept constant (the number of hosts and the patch area per parasitoid were kept constant). The model predicted and the experiments showed that parasitoids gain less offspring per unit of time when searching a patch together: superparasitism leads to mutual interference. No self-superparasitism should have occurred when parasitoids searched alone. This prediction was only met with females that had been kept in isolation in the days before the experiment; when stored in groups of four, self-superparasitism did occur. This indicates an ability of the parasitoids to assess the probability of future superparasitism by conspecifics.
Variation in the Mating System and Associated Parental Behaviour of Captive and Free-Living Cichlasoma Nigrofasciatum (Pisces, Cichlidae)
Authors: Keenleyside Miles H.A. , Bailey Robert C. , Young Vicki H.
Published: April 2008

C. nigrofasciatum typically breed in monogamous pairs with biparental care of the young for up to 6 weeks. In experimental ponds in southern Canada and streams in north-western Costa Rica two variations on this system were studied: male desertion followed by maternal care, and simultaneous bigamy by males. In the ponds, with a female-biased sex ratio, males deserted or became bigamous when their broods were at all stages from eggs to advanced, free-swimming fry. These departures from monogamy did not consistently influence brood survival, except that broods deserted by their father shortly after spawning did not survive, whereas those deserted when they were at least one week into the fry stage survived to independence with only their mother as guardian. Both in the ponds and at the field sites females with monogamous partners spent more time away from their broods than did deserted females, but only in the ponds did this correspond with reduced feeding by the deserted females. In nature all parental females foraged less often than did non-parental females, and this reduction was not strongly influenced by mate desertion. Brood defense behaviour by adults in monogamous pairs provided some evidence of division of parental labour. In the ponds guarding females attacked sub-adult juveniles more than males did, whereas in the field guarding females attacked non-cichlid fishes (mainly characins and poeciliids) and conspecific females and juveniles more than males did. Both in the ponds and the field guarding males attacked conspecific adult males more than females did. Most deserted, brood-guarding females seen in Costa Rican streams had young that were relatively large, mobile fry, approaching independence. This may reflect the need for both parents to guard their young during the first few days of free-swimming. They are probably highly vulnerable to predators at this stage and paternal desertion may be more costly than later, when they are stronger swimmers and better able to escape from predators.
Evolutionary Dissipation of an Antisnake System: Differential Behavior By California and Arctic Ground Squirrels in Above- and Below-Ground Contexts
Authors: Goldthwaite Ronald O. , Coss Richard G. , Owings Donald H.
Published: April 2008

Arctic ground squirrels (Spermophilus parryii ablusus) have been free from snake predation for about 3 million years. To evaluate the effects of this prolonged relaxation of natural selection, lab-born Arctic ground squirrels were compared to snake-inexperienced California ground squirrels (Spermophilus beecheyi fisheri) from a habitat where rattlesnake and gopher snake predation is intense. Their behavior was video taped during 10-min encounters with a Pacific gopher snake (Pituophis melanoleucus catenifer) in a seminatural above-ground setting and in an artificial burrow. In separate trials, a domesticated Norway rat was used as a control for the effects of encountering a novel animate object; this rat was enclosed in a slowly moving opaque nylon bag above ground but was allowed to move freely below ground. No evidence was found that, after prolonged relaxed selection from snakes, Arctic ground squirrels retained the specialized behavioral antisnake defenses evident in California ground squirrels. Although we originally hypothesized that the more constrained burrow context might limit the evolutionary dissipation of behavioral antisnake defenses, we found no evidence of a more intact system in Arctic squirrels below than above ground. Arctic squirrels used many of the same general kinds of motor patterns as California squirrels, but in ways that failed to differentiate the gopher snake from the rat in either above- or below-ground contexts. In contrast, the California squirrels tail flagged only in the presence of the snake above ground and differentially applied substrate-throwing at the snake and rat burrow intruders, harassing the snake more than twice as much as the rat. Above ground, California ground squirrels were more conservative toward both adversaries than Arctic ground squirrels were, keeping their distance and therefore experiencing fewer noxious consequences, such as snake strikes. However, this result was context dependent. Below ground, California ground squirrels were more willing than Arctic ground squirrels to approach and harass both burrow intruders. Although repeated striking evoked occasional snake-directed substrate throwing above ground, Arctic ground squirrels never threw substrate at the snake in the burrow. In comparison with California ground squirrels, Arctic ground squirrels appear to enter their first gopher snake encounter with both a much lower assessment of the risk involved and less clearly defined knowledge about how to deal with these risks. We conclude that 3 million years of genetic drift has altered the cognitive system structuring the meaning of snakes to Arctic ground squirrels in various settings.
Effect of Genotype and Litter Size On Discrimination of Mothers By Their Twelve-Hour-Old Lambs
Authors: Nowak R. , Lindsay D.R.
Published: April 2008

The ability of 12-h-old Border Leicester x Merino (BL x M) and pure Merino (M) lambs to seek a ewe and to discriminate their mothers from alien dams was tested in a two choice situation. When released in a triangular enclosure at 6 m from two penned ewes placed next to each other, most lambs reached a ewe before the end of the 5-min test. BL x M lambs were more attracted to the ewes than M lambs and could better discriminate their own mothers from alien dams. Although BL x M lambs were heavier than M lambs, the differences observed were mainly related to an effect of breed rather than to birth weight. There were no significant differences due to litter size or sex within each breed. On the other hand the differences between breeds were more marked in multiple than in single born lambs. This suggests the existence of an interaction between breed and litter size in the behavioural performances of very young lambs. It is concluded that young lambs can take an active part very early in life in the normal development of selective mother-young relationships. Also, 12 hours after birth, single and multiple BLxM lambs can discriminate between their own and alien mothers better than M lambs.