bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence of Energetic State on the Form of Stabilimentum Built by Octonoba sybotides (Araneae: Uloboridae)
Authors: Watanabe Takeshi
Published: March 2003

The influence of food supply on the type of stabilimentum built by Octonoba sybotides, an uloborid spider, was investigated in a laboratory experiment. Spiders were separated into two groups that built distinct stabilimenta (linear or spiral), and then further subdivided into two different feeding groups (food‐deprived and food‐supplemented). Food‐deprived spiders (a fruit fly every 10 d) tended to form spiral stabilimenta, whereas food‐supplemented spiders (a fruit fly every 2 d) tended to form linear stabilimenta. Furthermore, there was a significant difference in the distribution of stabilimentum forms before and after egg production. After egg production, which involves a large expenditure of energy, spiders tended to form spiral stabilimenta. These results suggest that the spider’s energetic state influences the type of stabilimentum built by O. sybotides, and that hunger induces the spider to form spiral stabilimenta.
Short‐range Homing in Fiddler Crabs (Ocypodidae, Genus Uca): A Homing Mechanism not Based on Local Visual Landmarks
Authors: Cannicci Stefano , Fratini Sara , Vannini Marco
Published: March 2003

This field study investigated the spatial strategies and homing ability of two East African fiddler crabs, Uca lactea annulipes and Uca vocans hesperiae, using various experimental procedures. A clear‐cut spatial segregation between the two species was observed, with U. l. annulipes occupying areas even a few centimetres above U. v. hesperiae. Females of both species were extremely faithful to their holes while the males exhibited behavioural differences. U. l. annulipes males were quite faithful to their holes; in contrast, U. v. hesperiae males, during a single low tide, visited several holes which they did not defend. Two displacement experiments were conducted in order to identify the stimuli that fiddler crabs use in their homing. In the ‘dislocation experiment’, the crabs were moved (by hand) 1 or 2 m away from their refuge and released. None of these crabs returned to its burrow and, moreover, the initial directions they followed were not homeward orientated. In the ‘translation experiment’, the crabs were passively translated while actively feeding. When the crabs attempted to go ‘home’ after the translation, they darted along a straight path that led them to points that would have corresponded to their homes if the translation had not taken place. After this first response crabs then commenced searching strategies that led half of them home. Short‐range homing seems to depend strongly on information actively gathered during the outward journey, other than local visual landmarks.
Thirteen‐lined Ground Squirrel (Sciuridae: Spermophilus tridecemlineatus) Antipredator Vigilance: Monitoring the Sky for Aerial Predators
Authors: Arenz Cody L. , Leger Daniel W.
Published: March 2003

Despite the success of antipredator vigilance research, the specific focus of this vigilance has been difficult to determine. We have previously shown that thirteen‐lined ground squirrels (Spermophilus tridecemlineatus) increase their vigilance when their lateral field of view is obstructed. In this paper, we describe an experiment in which we attempt to determine the predator class for which this vigilance is directed. Using six differentially occluded Plexiglas foraging boxes with hinged ‘eaves’, we were able to obstruct the squirrels’ view of the sky while not obstructing their view of terrestrial threats. In general, across the box types, when their sky view was obstructed, ground squirrels increased their vigilance by increasing the percentage of time spent withdrawn from the boxes. This result suggests that a significant portion of ground squirrel antipredator vigilance is directed at the sky and is surveillance for aerial predators.
Vocal Communication in Pigs: Who are Nursing Piglets Screaming at?
Authors: Appleby Michael C. , Weary Daniel M. , Taylor Allison A. , Illmann Gudrun
Published: March 2003

Vocalizations during competition among nursing piglets were studied to investigate their possible effects, functions and implications for welfare. In Expt 1, two experimental piglets in each of 14 litters were temporarily deprived of milk by covering their preferred teats on the sow’s udder. These piglets spent more time away from their teats than two control piglets, and vocalized frequently in the 2 min before milk ejection. Frequency of vocalization showed no consistent change over time within nursings; nor did it change in successive nursings despite the fact that hunger presumably increased. In Expt 2, tape recordings of intense vocalizations (screams) produced by piglets competing at the udder were played to 22 litters while they were nursing; each litter was played its own recording, a recording from another litter and silence as a control. Of 51 nursings analysed, 14 were terminated without milk ejection, all during playbacks. When the sow did nurse successfully during a playback, nursing was shorter (138 s) than during the silent controls (179 s). Both these responses by the sow might be expected to advance the next nursing. Piglets rarely showed any apparent response to screaming either from their littermates or from the loudspeaker. These results suggest that the calls function mainly as a signal to the sow that some piglets are being excluded from the current nursing episode.
Intraclutch Hatch Synchronization in Pheasants and Mallard Ducks
Authors: Persson Irene , Andersson Gunilla
Published: March 2003

Synchronization of hatching within clutches of precocial bird species can be achieved either by acceleration or retardation, i.e. by shortening or prolonging the incubation period. The ability of mallard (Anas platyrhynchos) and ring‐necked pheasant (Phasianus colchicus) embryos to accelerate or retard hatching was tested by incubating separate clutches, of which three eggs had 2 d longer or shorter incubation time than the others, and observing their individual time of pipping (breaking of the shell). Mallard embryos were able to delay hatching by on average 0.6 d (43% of the eggs delayed at least 1 d), but were better at acceleration (on average 1.3 d; 91% of the eggs accelerated more than 1 d). Conversely, pheasant embryos were only able to accelerate by 0.4 d (50% accelerated more than 1 d), but were better at delaying the hatching (1.2 days; 77% delayed more than 1 d). This difference between the species may depend on different degrees of relatedness within clutches in pheasants and mallards. It may also be an effect of the more developed sensory and neuromuscular systems in galliforms; a reduction of the incubation period would mean that the development of, for example, locomotion would be insufficient at hatching.
Kin Associations during Nest Founding in an Allodapine Bee Exoneura robusta: do Females Distinguish between Relatives and Familiar Nestmates?
Authors: Bull Nicholas J. , Adams Mark
Published: March 2003

True recognition of kin can have important fitness consequences in terms of directing altruistic behaviours toward close relatives (nepotism) and avoiding inbreeding. However, recent evidence suggests that some social insect species cannot or do not distinguish their closest relatives from among nestmates in important fitness‐based contexts. Such findings are relevant to kin selection theories where individuals are expected to preferentially rear close relatives in order to gain inclusive fitness benefits. Here, allozyme markers are used to examine whether female Exoneura robusta individuals preferentially nest with their closest kin when given a choice of familiar previous nestmates. The results suggest these bees do not prefer kin over non‐kin nestmates. Kin associations during nest founding in this species are probably due to philopatry and/or association with previously familiar nestmates.
Age Differences in the Responses to Adult and Juvenile Alarm Calls by Bonnet Macaques (Macaca radiata)
Authors: Ramakrishnan Uma , G. Coss Richard
Published: March 2003

This study examined the differential responses to alarm calls from juvenile and adult wild bonnet macaques (Macaca radiata) in two parks in southern India. Field studies of several mammalian species have reported that the alarm vocalizations of immature individuals are often treated by perceivers as less provocative than those of adults. This study documents such differences in response using field‐recorded playbacks of juvenile and adult alarm vocalizations. To validate the use of playback vocalizations as proxies of natural calls, we compared the responses of bonnet macaques to playbacks of alarm vocalizations with responses engendered by natural alarm vocalizations. We found that the frequency of flight, latency to flee, and the frequency of scanning to vocalization playbacks and natural vocalizations were comparable, thus supporting the use of playbacks to compare the effects of adult and juvenile calls. Our results showed that adult alarm calls were more provocative than juvenile alarm calls, inducing greater frequencies of flight with faster reaction times. Conversely, juvenile alarm calls were more likely to engender scanning by adults, a result interpreted as reflecting the lack of reliability of juvenile calls. Finally, we found age differences in flight behavior to juvenile alarm calls and to playbacks of motorcycle engine sounds, with juveniles and subadults more likely to flee than adults after hearing such sounds. These findings might reflect an increased vulnerability to predators or a lack of experience in young bonnet macaques.
Queens of the Paper Wasp Polistes fuscatus (Hymenoptera: Vespidae) Discriminate among Larvae on the Basis of Relatedness
Authors: Panek Laura M. , Gamboa George J.
Published: March 2003

The ability of queens of the paper wasp Polistes fuscatus to recognize larvae on the basis of colony origin was investigated in the laboratory. In a blind, binary choice paradigm, queens discriminated between larvae from their own colony and unrelated larvae, and between larvae from a sister colony and unrelated larvae. However, queens failed to discriminate between larvae from their own colony and larvae from a sister colony, indicating that queens of multiple‐foundress colonies may lack the ability to make intracolonial brood discriminations on the basis of relatedness. These results demonstrate that recognition of larvae is mediated by larval‐borne, genetically specified odors. Gas chromatograph/mass spectral analysis revealed that adults and larvae have similar cuticular hydrocarbon profiles, suggesting that the cues mediating larval and adult recognition may be the same.
Does Climate or Habitat Affect the Frequency of Cooperative Brood Rearing in Canada Geese?
Authors: Gosser Allen L. , Conover Michael R.
Published: March 2003

Canada geese (Branta canadensis) are unusual because individuals use either of two different brood‐rearing behaviors: cooperative broods (two or more merged broods attended by more than three parents) or two‐parent families. We tested whether cooperative broods form in response to habitat or climatic conditions by examining variation in cooperative brood frequencies among Canada geese nesting in Connecticut from 1982 to 1996. Percent of goslings raised in cooperative broods ranged from 0 to 100% at a given site in different years, but the pattern of annual variation was different at each site. The sites were in close proximity to each other and had similar climates; thus, the differences in annual variation among sites was not likely to be a response to climatic conditions. Cooperative brood frequencies also varied among sites in each individual year, but sites with the most gang brooding in one year often had the least the next. Such would not be expected if gang brooding occurred in response to non‐ephemeral habitat characteristics. Sites where gang brooding occurred and where it did not have similar food resources and predation risks. These findings failed to support the hypotheses that gang broods form in response to food competition or predation. Sites where gang broods occurred had more parent geese and more goslings than sites where they did not occur. Furthermore, the proportion of goslings raised in gang broods was correlated with the number of goslings and parents at the site. Our results support the hypothesis that gang broods form from the inadvertent mixing of goslings. This single factor, however, was not sufficient to account for all of the observed variation in gang brooding frequencies.
Placement, Retrieval, and Memory of Caches by Thirteen‐Lined Ground Squirrels
Authors: Devenport Jill A. , Luna Linda D. , Devenport Lynn D.
Published: March 2003

Mechanisms governing placement and retrieval of scatter hoards were investigated in 13‐lined ground squirrels (Spermophilus tridecemlineatus). The squirrels used several placement tactics, including relatively deep burial of seeds, avoidance of prominent objects, and cryptic placement, which would reduce chance discovery by competitors but that might also increase the difficulty of retrieval for the hoarder. Nevertheless, scatter hoards were unfailingly retrieved within a day or two after placement, despite experimental elimination or displacement of local sensory cues emanating from the sites. Artificial caches placed close to true caches were not discovered, indicating that recovery attempts were quite precise. These results imply that 13‐lined ground squirrels rely heavily on spatial memory for retrieval and are the first experimental demonstration of the importance of memory for cache recovery in a natural population of mammals.
Parasitized Salamanders are Inferior Competitors for Territories and Food Resources
Authors: Maksimowich Daria S. , Mathis Alicia
Published: March 2003

Parasites have been shown to impair the behaviour of their hosts, compromising the host's ability to exploit and compete for resources. We conducted two experiments to determine whether infestation with an ectoparasitic mite (Hannemania eltoni) was associated with changes in aggressive and foraging behaviour in the Ozark zigzag salamander, Plethodon angusticlavius. In a first experiment, male salamanders with high parasite loads were less aggressive overall than males with low parasite loads during territorial disputes. In addition, males with high parasite loads were more aggressive toward opponents with high parasite loads (symmetric contests) than toward opponents with low parasite loads (asymmetric contests). In contrast, males with low parasite loads did not adjust their level of aggression according to the parasite load of the opponent. In a second experiment, foraging behaviour of females was tested in response to ‘familiar’ (Drosophila) prey and ‘novel’ (termite) prey. Latency to first capture was significantly longer for parasitized than non‐parasitized females when tested with ‘familiar’ prey, but not for ‘novel’ prey. Our results suggest that parasite‐mediated effects may have profound influences on individual fitness in nature.
Opercular Flaps as Sexual Ornaments for Male Longear Sunfish (Lepomis megalotis): Male Condition and Male‐Male Competition
Authors: Goddard Kaye , Mathis Alicia
Published: March 2003

Male longear sunfish, Lepomis megalotis, have longer opercular flaps than females, and females are known to prefer males with longer flaps, suggesting that these exaggerated structures serve as sexual ornaments. We tested the hypothesis that opercular flap length is associated with body condition and is therefore potentially an honest indicator of male quality. Opercular flaps grew significantly faster than pelvic fin spines, a non‐sexually selected trait, regardless of diet treatment, suggesting an advantage to having fast‐growing opercular flaps. Growth indices (opercular flap growth divided by pelvic fin spine growth) of males fed a larger ration were greater than those of males fed a smaller ration, although the difference was marginally non‐significant. We also tested for an effect of opercular flap length on resource holding power by manipulating flap length on pairs of males matched for body length. In an experiment where opercular flaps were clipped to different lengths, only longer original (unmanipulated) flap length was associated with a significantly greater frequency of dominance. In a corollary experiment where opercular flaps were artificially lengthened, the abnormally long‐flapped males were dominant significantly more often than the ‘normal’ males given transparent extensions. These results indicate that the opercular flap length of male longear sunfish may serve as an honest indicator of male quality and may be used to assess the resource holding power of rival males.
Determining Social Rank in Ungulates: A Comparison of Aggressive Interactions Recorded at a Bait Site and under Natural Conditions
Authors: Côté Steeve D.
Published: March 2003

Researchers often assume that dyadic interactions at bait sites have similar outcomes to those occurring under natural conditions, but this assumption has seldom been tested. I used aggressive interactions recorded during 1994–97 among marked mountain goats (Oreamnos americanus) to compare dyadic relationships near an artificial salt lick with those observed under natural conditions. I also examined how observations recorded at the lick affected the structure of dominance matrices. The probability of winning an encounter was strongly and positively related to age, both under natural conditions and at the salt lick. The proportion of interactions that adult females lost to 2‐yr‐olds and the proportion won by the youngest individual among adult females, however, more than doubled at the salt lick compared to natural conditions. Two‐year‐old females were 22 times more likely to win interactions against 2‐yr‐old males at the lick than under natural conditions. A decrease in the directional consistency index revealed that the outcomes of repeated encounters of the same dyad were more inconsistent at the salt lick than elsewhere. When interactions recorded at the lick were added to female dominance matrices, the number of inconsistencies more than doubled and the strength of the inconsistencies increased 2–8 times compared to matrices restricted to interactions recorded under natural conditions. Interactions seen at the salt lick caused substantial changes in the hierarchical rank of individual goats. Because interaction rates were high and animals were very concentrated at the trap site, individual recognition may have been difficult, explaining the differences observed in dyadic relationships at the lick compared to natural conditions.
Meadow Voles (Microtus pennsylvanicus) and Prairie Voles (M. ochrogaster) Differ in Their Responses to Over‐Marks from Opposite‐ and Same‐Sex Conspecifics
Authors: Woodward Raymond L. , Bartos Kim , Ferkin Michael H.
Published: March 2003

Over‐marking occurs when one individual deposits its scent mark on the scent mark of a conspecific. Previous studies have shown that meadow voles (Microtus pennsylvanicus) and prairie voles (M. ochrogaster) that were exposed to an over‐mark of two same‐sex conspecifics, later responded similarly to the top‐scent mark but differed in their response to the bottom‐scent mark. In the present study, we examined the responses of meadow voles and prairie voles to same‐sex and mixed‐sex over‐marks to ascertain whether their responses reflect the different tactics which males and females in promiscuous (meadow voles) and monogamous (prairie voles) species use to attract opposite‐sex conspecifics and to compete with same‐sex conspecifics. Males and females of both species spent more time investigating the mark of the top‐scent donor than that of the bottom‐scent donor of an over‐mark. Meadow voles exposed to a mixed‐sex over‐mark spent more time investigating the mark of the opposite‐sex conspecific independently of whether it was from the top‐ or bottom‐scent donor. In contrast, prairie voles spent more time investigating the mark of the opposite‐sex donor if it was from the top‐scent donor. These results suggest that: (i) over‐marking serves a competitive function; (ii) the scent marks of individuals attract multiple mates in promiscuous species such as the meadow vole; and (iii) the scent marks of individuals establish and maintain pair bonds between familiar opposite‐sex conspecifics in monogamous species such as the prairie vole.
Age‐Related Microhabitat Segregation in Willow Tit Parus montanus Winter Flocks
Authors: Brotons Lluís , Orell Markku , Lahti Kimmo , Koivula Kari
Published: March 2003

It is expected that through flexibility in behaviour, flock living birds respond to the asymmetries in resource access derived from dominance relationships. We analysed the microhabitat use of willow tits in winter flocks and assessed possible factors which shape habitat segregation between adults and juveniles in different temperature regimes. When foraging in mild conditions (ambient temperature > 0°C), flocks split up into subgroups with adults foraging in inner parts of trees more often than juveniles. However, no differences were recorded in the vertical position occupied in trees. In harsh conditions (< − 4°C), flocks re‐united and juveniles further moved to outer parts of trees, increasing horizontal segregation between age classes. In mild conditions, vigilance behaviour was not related to the position of birds in trees, but in harsh conditions, scanning frequency was higher in outer parts of trees only for adults. In mild weather, juvenile position in trees was associated with body size and mass. The foraging microhabitat segregation detected in harsh conditions fits the age‐related hoarding distribution previously described in the same population. This supports the hypothesis that hoarded food is important in determining future foraging habitat use. Adult preference and intraspecific competition for safer or richer inner parts of trees as foraging sites during harsh conditions seems to determine the habitat segregation between adults and juveniles. Furthermore, we suggest that in mild weather, when foraging in the absence of adults, juveniles balance the costs of using a potentially dangerous microhabitat with the benefits of building energetically cheap and large food reserves through hoarding. The expected patterns of microhabitat segregation may differ in parids, depending on whether predation risk or other factors such as food availability are the main factors controlling habitat quality.
Call Convergence within Groups of Female Budgerigars (Melopsittacus undulatus)
Authors: Hile Arla G. , Striedter Georg F.
Published: March 2003

The budgerigar (Melopsittacus undulatus) is a promising model species for the study of adult vocal learning. To date, several studies have confirmed the existence of vocal plasticity and, more importantly, rapid imitation of contact calls by adult male budgerigars. Vocal learning has not been investigated in female budgerigars, however. Since one likely function of the contact call is to denote group affiliation, we tested the hypothesis that female budgerigars, when placed into groups, would develop a shared contact call. We recorded the contact call repertoires of eight adult female budgerigars that were unfamiliar with one another, then placed them into two groups. Each group was deprived of visual contact with other birds. Recording sessions continued for the subsequent 8 wks, and behavioral observations were also conducted during this time. Within 4–7 wks, females in both groups converged on a common call type. This rate of convergence is slower than that observed in prior experiments limited to male birds, and much slower than vocal imitation by male budgerigars paired with females. Therefore, while our study documents vocal plasticity in adult female budgerigars, it also suggests that female budgerigars learn new vocalizations more slowly than males do.
Male Mating Tactics in the ShrimpPalaemonetes pugio(Decapoda, Caridea): Precopulatory Mate Guarding vs. Pure Searching
Authors: Bauer Raymond T. , Abdalla Joseph H.
Published: March 2003

The guarding of females approaching a limited period of sexual receptivity is a common mating tactic of males. In many decapod crustaceans, such as the shrimpPalaemonetes pugio, females can only copulate during a short period after a reproductive molt. It has been predicted that mate guarding by males (pre‐copula) evolves in such species if sex ratios are not highly female‐biased and if males can detect the molt stage of the female. The mating tactics of males were investigated inP. pugio. Time‐lapse video observations were made on interactions among two males, a pre‐molt female, and an inter‐molt female (20 replicates). There was no evidence that males recognized a pre‐molt female until 24 h before its molt. Significant numbers of male contacts with pre‐molt females occurred 1 h before and after the female molt. Copulation took place within 1–3 min of the molt. No behavior commonly associated with mate guarding in decapods was observed – no clasping, agonistic behavior, or close association. It is concluded that the male's mating tactic is pure searching, wherein males haphazardly contact many females in order to find a receptive one. The high encounter rate in nature of these very mobile, aggregated shrimps is proposed as the factor responsible for the evolution of pure searching. It is hypothesized that pure searching is the male tactic of the many species of decapod shrimps with small males, sexually monomorphic cheliped weapons, and aggregated populations.
Age Differences in the Response of California Ground Squirrels (Spermophilus beecheyi) to Conspecific Alarm Calls
Authors: Hanson Mark T. , Coss Richard G.
Published: March 2003

Juvenile California ground squirrel responses to adult alarm calls and juvenile alarm calling may be modified during development to achieve adult form. Adult conspecific chatter and whistle alarm calls were played back to juvenile and adult ground squirrels at an agricultural field site. In response to chatter playbacks, adults spent more time visually orienting to the environment and less time out of view and in covered habitats than juveniles; the converse was true in response to whistle playbacks. To test the evocativeness of juvenile calling, a subset of adult subjects received juvenile chatter and whistle playbacks. Adults spent less time out of view to juvenile call types than to adult calls, and showed more similar responses to juvenile chatters and whistles than to adult chatters and whistles. Age differences in the ground squirrel’s alarm call system may reflect adjustments to changing risks during development.
Dominance Interactions Regulate Worker Mating in the Polygynous Ponerine AntGnamptogenys menadensis
Authors: Gobin Bruno , Billen Johan , Peeters Christian
Published: March 2003

In queenless ants, workers compete aggressively to be reproductives instead of sterile helpers. To limit the number of reproductives, either mating or egg‐laying by mated workers can be regulated. InGnamptogenys menadensis, all mated workers reproduce, and field data presented here indicate that mating is not random. We removed gamergates experimentally (n=16 groups) to induce mating and gamergate replacement. Virgin workers engaged in agonistic interactions, allowing us to classify them into two groups: dominants performed antennal boxing and biting, while subordinates did not. However, a few subordinates cooperated to immobilize individual dominant workers. This effectively reduced the number of dominants because immobilized dominants became subordinates. Six to 12 wks after the removal of reproductives, between one and eight dominants per colony started to perform ‘sexual calling’ outside the nest entrance. Sixteen (out of 33) dominants mated with foreign males introduced in five experimental groups. None of the subordinate workers mated. The probability of mating is thus regulated by dominance interactions among workers and immobilizations initiated by infertile workers in this polygynous queenless ant.
The Behavior of Honey Bees (Apis mellifera ligustica) during Queen Duels
Authors: Gilley David C.
Published: March 2003

Conflict is rare among the members of a highly cooperative society such as a honey bee colony. However, conflict within a colony increases drastically during colony reproduction (‘swarming’) when newly produced queens fight each other until only one queen remains in the nest. This study describes the behavior of queens and workers during naturally occurring queen combat. The duels of five pairs of queens were observed in three observation colonies. A typical duel is described qualitatively and the events of all five duels are described quantitatively. Several aspects of duels that are of particular interest are examined in detail, including the behavior of queens near capped queen cells, worker aggression toward queens, queen tooting, and the relation of queen and worker behavior to the outcome of the duel. The results of this investigation serve as a foundation for rigorous tests of hypotheses regarding the adaptive significance of queen and worker behavior during queen combat. The results presented suggest that: young queens patrol queen cells to kill rival queens while they are vulnerable; workers aggress queens to prevent them from destroying queen cells; queens toot to inhibit worker aggression; workers immobilize queens to make them easy targets for rival queens; and queens eject hind‐gut contents to cause their rival to be immobilized by the workers.
Cues for Early Discrimination of Conspecific Song in the White‐Crowned Sparrow (Zonotrichia leucophrys)
Authors: Soha Jill A. , Marler Peter
Published: March 2003

In song learning, white‐crowned sparrows (Zonotrichia leucophrys) begin memorizing conspecific song models at around 20 d of age. Even prior to song memorization, however, between 10 and 20 d of age, these birds respond differently to playbacks of conspecific and heterospecific songs. To investigate the acoustic cues underlying this early song discrimination, we measured the vocal responses of newly fledged young to playbacks of modified conspecific and heterospecific songs. Fledgling white‐crowned sparrows responded more strongly to songs containing conspecific notes than to songs containing notes from other species. In contrast, the presence or placement of an introductory whistle, present in all white‐crowned sparrow songs, did not affect response levels. A whistle has previously been shown to serve as an acoustic cue for song memorization and production in this species. Such different responses to the species‐typical introductory whistle at different stages suggests that developmental changes occur in the template system underlying song learning, the factors governing song recognition, or both.
Social Influence on Early Foraging of Domestic Chicks (Gallus gallus) in a Near‐to‐Nature Procedure
Authors: Gajdon Gyula K. , Hungerbühler Nadja , Stauffacher Markus
Published: March 2003

The aim of this study was to investigate the social influence of single chicks with different foraging experience on the behaviour of their group members during the first days after hatching. In contrast to the duplicate cage procedure normally used in social learning studies, four naïve group members could freely interact with a tutor or a control chick in an enriched 20‐m2 test arena. This arena contained two types of food caches with differently coloured food. The tutor was 3 d older than its group members and was trained to feed from one of the two food cache types, whereas the control chick was not familiar with the characteristics of the test arena and was either of the same age or 3 d older than its group members. During the first 9 d after hatching, the foraging activity of 32 chick groups was tested in 15 trials per group. Groups with a 3 d older but inexperienced control chick had the least foraging success whilst groups with a naïve control chick of the same age compared more favourably with the groups with experienced tutors than with groups that included older control chicks. In a second experiment, a tutor compartment was introduced into the test arena in order to compare a situation of unrestricted contact possibilities with the duplicate cage procedure in which tutor and bystanders are separated by a Perspex divider. The tutor compartment was opened for some test groups, allowing free interaction between tutor and naïve chicks. Those chicks which could only watch the tutor through the Perspex developed a preference for the tutor’s food type and discovered this food type as fast as the chicks of groups with unrestricted interactions. However, a relatively large proportion of groups (3 out of 8) did not develop successful foraging behaviour at all, whereas the successful groups showed longer feeding latencies during the subsequent trials than groups which had unrestricted contact with their tutor. This indicates an inhibiting effect of the duplicate cage procedure. It is concluded that when testing chicks of a few days of age, a distinction should be made between (i) the social influence on food particle preferences and (ii) the social influence on learning where to find food. This is important for generalizations taken from duplicate cage procedures without any environmental enrichment, as this restrictive setting only allows detection of food particle preferences.
Pheromonal Recognition of Females Takes Precedence over the Chromatic Cue in Male Iberian Wall Lizards Podarcis hispanica
Authors: López Pilar , Martín José
Published: March 2003

Sex recognition is based on colour signals in many species of lizards. However, olfactory stimuli are also clearly involved, and many species might rely more on chemoreception. We aimed to examine whether colour pattern or odours, or both, are used in sex recognition and which cues elicit courtship of females by males of the lizard Podarcis hispanica. We experimentally manipulated the coloration and odour of female P. hispanica, thereby creating groups with all combinations between coloration and odour of males and females. Using data from staged encounters, we compared the responses of resident males to manipulated and unmanipulated individuals (males and females). Responding males reacted significantly more aggressively to female intruders with male odours, independently of their coloration. Nevertheless, coloration seemed to be important in long‐distance sex recognition since, in the first minutes, females painted as females received a lower number of aggressive responses. Both colour and odour were important in eliciting male courtship. However, females painted as females and with female odours were preferentially courted. Comparisons with unmanipulated male and female intruders agreed with these expectations. Therefore, at close range, odoriferous cues seem to be more important than colour patterns in sex recognition, but female coloration is also useful at long range to deter the aggressive response of males and to elicit courtship in conjunction with odours.
Adult Song Sparrows do not Alter their Song Repertoires
Authors: Nordby J. Cully , Campbell S. Elizabeth , Beecher Michael D.
Published: March 2003

To understand fully the function of vocal learning, it is important to know when, during an individual’s lifetime, learning occurs. Songbirds are generally categorized into two groups with respect to their adult song learning ability. ‘Open‐ended’ song learners are able to learn to produce new songs in adulthood, whereas ‘age‐limited’ song learners can only acquire songs during their first year of life. Researchers have long assumed that certain oscine species are open‐ended or age‐limited song learners, but the evidence to date has been inadequate to test these assumptions for most species. We tested the hypothesis that song sparrows (Melospiza melodia) are age‐limited song learners who do not alter their song repertoires in adulthood by examining the song repertoires of 24 color‐banded males who were fully recorded in two, three or four different years. We compared sonagrams of the song types produced by males in different years and looked for any changes in repertoire composition (i.e. added or dropped song types). With few exceptions, males produced song repertoires that were identical in every year they were recorded. The exceptions (four males who did not produce one of their song types during one recording session) were all cases in which we believe that we missed recording a song type that a male did indeed have, not that the males dropped a song type. The finding that adult males do not alter the composition of their song repertoires provides strong evidence that song sparrows are age‐limited song learners. Although it is possible that song sparrows make subtle within‐song type changes across years, such changes would not necessarily constitute new song learning.
In‐Hive Behavior of Pollen Foragers (Apis mellifera) in Honey Bee Colonies Under Conditions of High and Low Pollen Need
Authors: Weidenmüller Anja , Tautz Jürgen
Published: March 2003

Pollen collection in honey bees is regulated around a homeostatic set‐point. How the control of pollen collection is achieved is still unclear. Different feedback mechanisms have been proposed but little is known about the experience of pollen foragers in the hive. A detailed documentation of the behavior of pollen foragers in the hive under different pollen need conditions is presented here. Taking a broad observational approach, we analyze the behavior of individual pollen foragers in the hive between collecting trips and quantify the different variables constituting the in‐hive stay. Comparing data from two colonies and 143 individuals during experimentally induced times of low vs. times of high pollen need, we show that individual foragers modulate their in‐hive working tempo according to the actual pollen need of the colony: pollen foragers slowed down and stayed in the hive longer when pollen need was low and spent less time in the hive between foraging trips when pollen need by their colony was high. Furthermore, our data show a significant change in the trophallactic experience of pollen foragers with changing pollen need conditions of their colony. Pollen foragers had more short (< 3 s) trophallactic contacts when pollen need was high, resulting in an increase of total number of trophallactic contacts. Thus, our results support the hypothesis that trophallactic experience is one of the various information pathways used by pollen foragers to assess their colony's pollen need.
The Role of Female Behavior in Maintaining Monogamy of a Coral‐Reef Filefish
Authors: Kokita Tomoyuki
Published: March 2003

The corallivorous filefish Oxymonacanthus longirostris is a predominantly monogamous species without parental care. Polygyny reduces female fitness because monogamous females benefit from male assistance with feeding–territory defense that secures both a feeding area and time to feed. I studied the strategy of females to prevent polygyny, with the help of field observations and manipulative field experiments. Monogamous females always behaved aggressively towards intruding floater females. When a caged male or female was placed within the territory of a monogamous pair, the resident female was more likely to pay attention to the caged female than to the caged male. Experimentally transplanted floater females succeeded in settling as secondary females in the monogamous territory more frequently when the resident female was caged. These results suggest that monogamous females behave aggressively towards floater females to defend their mating status; such aggressive behavior is successful in preventing polygyny. Furthermore, the removal experiment showed that polygynous (especially secondary) females moved to territories of widowed males located near them more frequently than monogamous females did. This outcome indicates that polygynous females can change their mating status and escape polygyny by moving to another territory if the opportunity occurs. Thus, female behavior can play an important role in the maintenance of monogamy and in lowering the level of polygyny within populations of this species.
Dialect Discrimination by Male Orange‐Tufted Sunbirds (Nectarinia osea): Reactions to Own vs. Neighbor Dialects
Authors: Leader Noam , Wright Jonathan , Yom‐Tov Yoram
Published: March 2003

Male orange‐tufted sunbirds (Nectarinia osea) exhibit distinct song dialects throughout Israel. Recently, two distinct local dialects with a sharp boundary were discovered in a small (1.5 km2) urban neighborhood densely inhabited by 63 territorial sunbird pairs. We conducted playback experiments to determine song dialect discrimination capability by sunbird males in this neighborhood. Males of both dialects responded significantly more strongly to playback of their own dialect than to that of the adjacent dialect. In spite of the extreme proximity between the two dialect areas, we found no effect of distance to the neighboring dialect on the intensity of any the behavioral responses. We suggest that due to the complex acoustic properties of this urban neighborhood, sunbirds are extremely limited in the number of neighboring males they can assess to establish what the local song is. A stronger response to one's own dialect is therefore expected, and we discuss how local dialects could be maintained via this mechanism regardless of the very small distances between territories and dialect populations.
Maternal Influences on Feeding and General Activity in Domestic Chicks
Authors: Wauters Aline‐Marie , Richard‐Yris Marie‐Annick , Talec Nolwenn
Published: March 2003

The aim of this study was to determine if and how the presence of a hen influences the behaviour of chicks and, more precisely, their food preferences. We observed two types of young, brooded and non‐brooded chicks in the presence of three different food types. Results revealed that brooded chicks performed more locomotion and more sustained feeding activities than non‐brooded chicks. Moreover, brooded chicks had different preferences from non‐brooded chicks and very clearly followed their mother's preferences. We concluded that social facilitation and local enhancement could play a significant role in determining the importance of feeding activities and preferences of brooded chicks.
Fighting and Mating Between Groups in a Cooperatively Breeding Mammal, the Banded Mongoose
Authors: Cant M. A. , Otali E. , Mwanguhya F.
Published: March 2003

Many cooperatively breeding animals actively defend a territory containing resources such as food and shelter, which are essential for reproduction. Some observations, however, indicate that conflicts between groups are often triggered by the attempts of males or females, or both, to gain extra‐group copulations. We studied interactions between 12 groups of banded mongooses (Mungos mungo) in Uganda to test whether the frequency of inter‐group encounters was linked to the reproductive status of females, and conducted an experiment to examine the responses of individuals to mongooses from other groups. The rate at which focal groups fought with other groups was higher when its females were in estrous, suggesting that many fights take place over access to mates. Both males and estrous females were instrumental in instigating encounters with rival groups, and extra‐group copulation in the midst of a fight was observed on three occasions. We experimentally simulated encounters with foreign individuals by presenting each of six groups with cages containing a male and a female from a rival group. Subordinate males were the first to investigate these ‘intruders’, spent more time around the intruders' cages, and were more aggressive to the intruders than either dominant males or females. Subordinate males directed more attention and aggression towards the male intruder than the female intruder. We suggest that male banded mongooses actively seek extra‐group copulations in pursuit of paternity, while females may actively seek extra‐group copulations as a way of reducing inbreeding depression.
Why do Juvenile Chinese Pit‐Vipers (Gloydius shedaoensis) Select Arboreal Ambush Sites?
Authors: Shine Richard , Sun Li‐xin , Kearney Michael , Fitzgerald Mark
Published: March 2003

Ontogenetic shifts in habitat use are widespread, especially in ectothermic taxa in which juveniles may be an order of magnitude smaller than large adult conspecifics. The factors that generate such habitat shifts are generally obscure, but we studied an unusual system that allowed us to compare consequences of habitat selection between adults and juveniles. Pit‐vipers (Gloydius shedaoensis) on a small island in north‐eastern China feed almost entirely on seasonally migrating birds. During the spring bird‐migration period, individual snakes consistently re‐used either arboreal or terrestrial ambush sites. Snakes in trees were smaller (and more philopatric) than snakes on the ground. This ontogenetic shift in habitat use may reflect the difficulty of capturing birds on the ground, especially by small snakes. In laboratory trials, large (adult) pit‐vipers struck faster, further and more accurately than did small (juvenile) snakes. In experiments with free‐ranging snakes, the proportion of strikes hitting the bird was lower for juveniles than for adults, and lower for terrestrial snakes than for arboreal snakes. Additionally, adult snakes generally seized the bird by the head whereas juveniles frequently struck the body or wings (and thus, obtained a less secure grip). Arboreal ambush sites may facilitate prey capture not only because they give access to smaller birds but also because they render the bird's location more predictable and, hence, enable the snake to position itself optimally prior to the prey's arrival. Because juvenile pit‐vipers are less capable strikers, and are small relative to available prey items, they may benefit from the greater ease of prey capture from branches. Thus, the ontogenetic shift in habitat selection within this species may be because of ontogenetic shifts in the vipers’ ability to capture and ingest large, mobile prey.