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1.
Punzo F Preshkar C 《Journal of environmental biology / Academy of Environmental Biology, India》2002,23(4):341-345
The purpose of this study was to determine if environmental chemical cues associated with prey can affect subsequent prey choice in wolf spiderlings (Hogna carolinensis). After emergence from the egg sac, three groups of 10 spiderlings were each fed for one-week on one of three naturally-occurring prey species: group 1 fed on nymphs of the field cricket Gryllus pennsylvanicus; group 2 (house cricket, Acheta domesticus); group 3 (mole cricket, Gryllotalpa hexadactyla). They were then tested for subsequent prey preference in choice tests conducted in a plastic arena. Each spiderlings was presented simultaneously with one individual of each prey species in a randomized design. Spiderlings exhibited a significant first preference for the original diet. Thus, experience with certain foods (environmental chemical cues) encountered by newly hatched spiderlings can affect subsequent prey preference in this species. 相似文献
2.
For potentially cannibalistic animals such as spiders, the ability to recognize and avoid kin and/or preferentially cannibalize non-relatives would permit exploiting conspecifics as prey while minimizing loss of inclusive fitness. We investigated the effects of relatedness and availability of alternative food on cannibalism tendency in pairs of juvenile Hogna helluo (Walckenaer), a North American wolf spider (Araneae: Lycosidae). For second-instar spiderlings (dispersing stage), cannibalism was more likely among pairs of non-sibs than pairs of sibs and, interestingly, was also more likely when other prey were available. We found no evidence of increased cannibalism in pairings involving broods of greatest average size disparity, indicating that size differences are unlikely to explain differences in cannibalism tendency. Additionally, the relative number of deaths from cannibalism or other causes did not increase with increasing risk of starvation. For third-instar spiderlings, which had lived independently of their mother and sibs following dispersal, cannibalism rates were very high in all treatments and there were no significant effects of relatedness or food availability. Our results suggest that spiders with predominantly solitary lifestyles may bias cannibalism toward non-kin during the juvenile associative period, and that this effect is lost in the subsequent instar. Results are discussed in the context of several potential mechanisms that might result in differential cannibalism.Communicated by M. Elgar 相似文献
3.
Lore M. Ruttan 《Behavioral ecology and sociobiology》1990,27(3):169-173
Summary
Theridion pictum (Walckenaer) is a subsocial spider, that is, the mother actively takes care of her offspring for an extended period of time after they emerge. It is demonstrated that spiderling dispersal is affected by the availability of food in the maternal web. Experimental manipulations indicate that in those webs where less food was provided, spiderlings dispersed significantly earlier and in significantly greater numbers. These results illustrate the importance of food availability as a permissive factor in the evolution of social spiders from subsocial ancestors. Food availability also affects the pattern of sex-biased philopatry and dispersal. Although both sexes are more likely to remain in the maternal web when more food is available, females are relatively more likely to do so. When less food is available, females are relatively more likely to disperse than are males. 相似文献
4.
In order to remain stable, dispersed social groups have to solve two fundamental problems: the coordination of movement and cohesiveness within a group and the spacing between the groups. Here, we investigate mechanisms involved in intra-group coordination and inter-group spacing using the golden brown mouse lemur, Microcebus ravelobensis, as a model for a nocturnal, solitary foraging mammal with a dispersed social system. By means of radiotelemetry and bioacoustics we studied the olfactory and vocal behaviour during nocturnal dispersal and reunion of five sleeping groups.All groups used 3–17 sleeping sites exclusively, suggesting a sleeping site-related territoriality and competition for them. The occurrence of olfactory and vocal behaviour showed an asymmetrical temporal distribution. Whereas marking behaviour was observed exclusively during dispersal, a particular call type, the trill, was used by all groups during reunions. Interestingly, these trills carried group-specific signatures.Our findings provide the first empirical evidence for nocturnal primates in a natural environment that olfactory signals represent an important mechanism to regulate the distribution of different groups in space, whereas acoustic signals control intra-group cohesion and coordination. 相似文献
5.
In the meerkat (Suricata suricatta), a cooperative mongoose, pups follow potential feeders while the group is foraging and emit incessant calls when soliciting
food from them. In contrast to a ’stationary’ brood of chicks, in which nestlings are fed at a fixed location, meerkat pups
are ’mobile’ and become spread out. The question arises whether meerkat pups that experience different constraints to those
facing chicks have evolved similar begging strategies. This paper describes the vocalisations that meerkat pups emit in the
context of begging and investigates the influence of these calls on food allocation by older group members and on the behaviour
of littermates. Meerkat pups use two types of calls when soliciting food from a potential feeder. The most common is a ’repeat’
call, which pups emit continuously when following an older forager over several hours a day. In addition, when a potential
feeder finds a prey item, the pups next to it emit a bout of calls with increased calling rate, amplitude and fundamental
frequency, termed ’high-pitched’ calls. Observations, together with playback experiments, showed that more prey was allocated
to pups that called longer and more intensely. The pup closest to a feeder was almost always fed. The probability of emitting
high-pitched calls did not depend on the time since a pup had received food, and the change from repeat to high-pitched calls
occurred suddenly. The main function of the high-pitched call, therefore, does not appear to be to signal a pup’s hunger state.
More likely, the two calls, in the context of begging, may be an adaptation to energetic constraints in a mobile feeding system.
Pups, which are dispersed during foraging, may emit repeat calls over long periods to prevent potential feeders from eating
all the prey themselves. At the moment a potential feeder finds prey, pups may give the more intense high-pitched calls to
direct feeders to bring the food item to them and not to a littermate. Therefore, unlike the stationary feeding system where
chicks emit one type of begging call when the feeder approaches the nest, meerkats, with a mobile feeding system, have evolved
two discrete types of vocalisations in the context of begging.
Received: 22 November 1999 / Revised: 1 July 2000 / Accepted: 17 July 2000 相似文献
6.
H. G. Smith L. Wennerberg Torbjörn von Schantz 《Behavioral ecology and sociobiology》1996,38(3):191-197
The behaviour of a male bird towards a potential mate and her clutch may depend both on his expected paternity and on the
likelihood that she will produce a replacement clutch if he commits infanticide. In this study we evaluate the choices made
by replacement male European starlings Sturnus vulgaris. By removing males before and during laying, we induced other males, mainly neighbours, to mate with the reproductively active
females. When the original male was removed before laying, a new male adopted the subsequent clutch in 14 out of 15 cases.
When ten females were widowed during their laying period, replacement males never adopted their clutches. The paternity of
replacement males was a function of when they replaced the former male. When replacement occurred more than 3 days before
egglaying, the new male fathered nearly all offspring; when it occurred the day before laying, the new male still fathered
more than every second young. When the original male was removed during his mate’s laying period, in five out of ten cases
a replacement male committed infanticide by throwing out the eggs, but this only occurred in one out of 15 cases when removal
took place before laying. The evidence for infanticide actually being committed by the replacement male was circumstantial.
Four out of six of the females affected by apparent infanticide produced replacement clutches in which the male presumably
had higher paternity than in the original clutch. In all cases, the male adopted the replacement clutch. In five cases when
the original male was removed during laying, the neighbours neither adopted the brood nor committed infanticide, although
they sometimes were seen courting the widowed female and copulating with her. These cases occurred later during laying than
those were males comitted infanticide. The time from infanticide to the laying of the replacement clutch tended to increase
as infanticide was committed later in the laying sequence. We conclude that strategies of potential replacement males are
influenced by their expected paternity in the current brood and the probability that the female will produce an early replacement
clutch.
Received: 10 March 1995 / Accepted after revision: 28 October 1995 相似文献
7.
In young-of-the-year perch (Perca fluviatilis), individuals within groups differed in the degree of boldness, estimated by habitat utilisation and feeding activity in visual contact with a potential predator. We looked at changes in individual behaviour in connection with change of group composition. During the first period, perch were randomly assigned to groups, and time spent in open habitat versus in vegetation and number of prey attacks were registered. The perch were then categorised into personality types (shy, bold, intermediate) according to their behaviour. During the second period, fish were observed when sorted into new groups, each containing only one personality type. Shy individuals showed the largest changes in behaviour, and increased both the time spent in the open and the number of prey attacks when placed into the new groups. Feeding activity in shy fish during the second period was affected by group composition during the first period. After regrouping, bold individuals decreased their time in the open, whereas intermediate individuals did not change behaviour. Time in the open habitat was, to some extent, influenced by the behaviour of the other members of the group, but number of prey attacks was not. The behaviour of fish of the different personality types we have defined in this study seemed to be based on innate traits, but also modified by the influence of other group members and by habituation to the environment.Communicated by J.Krause 相似文献
8.
Dispersal attempts can be costly and may often end in failure. Individuals should therefore only disperse when the benefits
of dispersal outweigh the costs. While previous research has focussed on aspects of the individual that may affect dispersal
success, social factors may also influence dispersal outcomes. One way of achieving successful dispersal could be through
cooperative, or coalition dispersal. I investigated this possibility in the cooperatively breeding Arabian babbler Turdoides squamiceps. I found that coalition dispersal appears to be an effective strategy to ensure the success of dispersal attempts, with coalitions
more successful than lone individuals at taking over the breeding position in a new group. Lone dispersal was more costly
than coalition dispersal, with lone individuals suffering a greater loss of body mass during dispersal attempts. These results
suggest a substantial short-term benefit for this type of cooperative behaviour. There was no evidence for dispersal polymorphism
in the population, with no detectable phenotypic difference between dispersers and non-dispersers or those that dispersed
as part of a coalition compared with those that dispersed alone. 相似文献
9.
Subsocial spiders demonstrate an intermediate stage in the evolution of permanent sociality. Cooperative hunting is an important attribute of their sociality, but has not been documented in subsocial arthropods. After cannibalizing their mother, young of the subsocial spider Amaurobius ferox (Araneae, Amaurobiidae) remain together for several instars and feed communally. We monitored the collective prey capture behavior of the spiderlings. All the clutches showed collective capturing sequence (latency–orientation–moving–touching–seizing–feeding) toward the prey that was 10 times more massive than each individual. The first three individuals that exhibited attacking behavior were responsible for 90% of the total number of attacks, while 68% of the individuals within the group never exhibited attacks during the first 10 min following the introduction of prey into the communal web. First arriving individuals at the prey most often seized the antennae and legs of the prey, which probably facilitate access to the prey for subsequent individuals. The spiderlings that arrived later occupied more likely the abdomen and thorax, which contain more nutrition than the extremities occupied earlier. The individual apportionment of collective hunting behavior suggests a coordinated teamwork among individuals. 相似文献
10.
We present a hitherto unknown prey perception strategy in bats: Myotis nattereri (Vespertilionidae, Chiroptera) is able to perceive prey by echolocation within a few centimeters of echo-cluttering vegetation,
by using frequency-modulated search signals of very large bandwidth (up to 135 kHz). We describe the species’ search behavior
and echolocation repertoire from the field and from experiments in a flight tent. In the field, bats varied signal parameters
in relation to their distance from vegetation and usually flew close to vegetation. In the flight tent, M. nattereri detected and localized prey by echolocation alone as close as 5 cm from vegetation. Apparently, the bats were able to tolerate
some overlap between prey and clutter echoes. Passive prey cues (vision, olfaction, prey-generated sounds) were not used in
prey perception. The bats selected prey by size. The animals performed aerial catches and produced approach sequences typical
for aerial hawking bats, but were able to do so within a few centimeters of the substrate. M. nattereri thus has access to silent, suspended prey very close to vegetation (e.g., spiders, and caterpillars on threads).
Received: 29 September 1999 / Received in revised form: 12 February 2000 / Accepted: 12 February 2000 相似文献
11.
D. J. Green H. L. Osmond M. C. Double A. Cockburn 《Behavioral ecology and sociobiology》2000,48(6):438-446
Empirical and theoretical studies have only recently begun to examine how females use complex multi-component displays when
selecting mates. Superb fairy-wrens are well suited to the study of female choice because females have control over extra-group
paternity and cuckold their mates at high rates, while males possess a variety of sexually selected traits. Available evidence
suggests that females base their extra-group mate choice on the timing of male moult into breeding plumage or the onset of
display. However, males continue to perform elaborate displays throughout the season, and direct most displays to females
during their fertile period. We therefore conducted focal observations on fertile females to quantify the frequency of male
display and used microsatellite genotyping to compare the role of display rate during the breeding season and the timing of
male moult on female mate choice. We show that the addition of data on male display rate does not improve our ability to predict
which males obtain extra-group paternity. The timing of male moult into breeding plumage remains the only predictor of male
extra-group reproductive success. Nevertheless, we found that males displayed more to females that were unable to select extra-group
mates on the basis of the timing of moult or the onset of display. This raises the possibility that there are circumstances
when females use display rate to discriminate between potential extra-group sires. Overall this study supports the theoretical
prediction that females are more likely to base their mate choice on reliable indicators of male quality such as fixed morphological
traits and displays of endurance, in this case an early moult into breeding plumage and the performance of an elaborate display
during the winter, than a flexible behavioural trait such as display rate during the breeding season.
Received: 26 January 2000 / Revised: 1 August 2000 / Accepted: 26 August 2000 相似文献
12.
Behavioral and demographic changes following the loss of the breeding female in cooperatively breeding marmosets 总被引:3,自引:0,他引:3
C. Lazaro-Perea C. S. S. Castro R. Harrison A. Araujo M. F. Arruda C. T. Snowdon 《Behavioral ecology and sociobiology》2000,48(2):137-146
Recent models of the evolution and dynamics of family structure in cooperatively breeding vertebrates predict that the opening
of breeding vacancies in cooperatively breeding groups will result in (1) dispersal movements to fill the reproductive position,
and (2) within-group conflict over access to reproduction. We describe the behavioral and demographic changes that followed
the creation of breeding vacancies in three wild groups of cooperatively breeding common marmosets (Callithrix jacchus). Replacement of the breeding female was rapid when no adult females remained in the group, but did not occur for several
months when other adult females were present. Aggression of adult animals towards same-sex potential immigrants was associated
with a period of reduced affiliation, increased intragroup agonism, no intragroup sexual behavior, and frequent extragroup
copulations. This ended with the fissioning of groups along sexual lines. After replacement, multiple males copulated with
multiple females and vice versa, with no increases in sexually related aggression. Female-female conflict was resolved through
infanticide. The lack of direct conflict between males is consistent with cooperative polyandry. After a breeding vacancy
appeared, marmoset groups showed conflict of interests among group members similar to those shown by cooperatively breeding
birds, but they used different behavioral mechanisms to resolve those conflicts. Our data provide important evidence from
a cooperatively breeding mammal to support Emlen’s model for the evolution of vertebrate families, but they suggest that species-specific
inter- and intrasexual competitive strategies should be considered before the model can be applied to other cooperatively
breeding vertebrates.
Received: 23 November 1999 / Received in revised form: 28 March 2000 / Accepted: 1 April 2000 相似文献
13.
E. Sparrevik 《Marine Biology》1999,133(3):437-441
Laboratory experiments were performed to investigate the effects of sediment texture and presence of non-moulting conspecifics
on size-specific moulting survival of the omnivorous benthic isopod Saduria entomon (L.). The moult survival of S. entomon was significantly higher in coarse sand than in very soft muddy clay sediment. However, there was no size-related difference
in moult survival between the substrates. Due to cannibalism, moult survival of S. entomon was substantially reduced in the presence of non-moulting conspecifics. Moult survival was higher when the moulter was larger
than the non-moulters compared to when the moulter was smaller. In contrast, the absolute size of the moulter or the non-moulters
did not affect moult survival. The sex of the moulting or non-moulting isopods had no effect on the survival of the moulters.
Based on the results from laboratory experiments, sediment texture and cannibalism are suggested to affect survival during
moult of S. entomon in the field.
Received: 12 February 1998 / Accepted: 14 November 1998 相似文献
14.
We tested the influence of limiting access to prey on larval development of the crabs Cancer magister and Hemigrapsus oregonensis by raising their Stage 1 larvae in the laboratory on different prey densities and with various periods of access to prey.
Experiments were conducted in 1995 and 1996 at the Shannon Point Marine Center in Anacortes, Washington, USA. Our results
show that crab larvae do not require continuous access to prey for optimal development nor do they appear to require light
for prey capture. Survival and duration of Stage 1 C. magister fed continuously on only one-fourth the amount of the control density of prey and those fed at the control density for only
6 h per day were the same as for larvae fed continuously at the control density (20 ml−1). Larvae with cyclic access to prey at the control density for 24 h and then starved for 72 h showed significantly lower
survival and longer instar duration to Stage 2. Experiments on Stage 1 H. oregonensis which investigated a combination of prey density, period of access to prey and light/dark conditions during feeding revealed
that survival decreased with decreasing prey density or with decreasing feeding period, but no differences were observed during
periods of limited prey availability as a function of light or dark conditions. Stage duration was not affected by reduced
prey density nor by the light/dark condition at the time of feeding, but it was prolonged when the period of access to prey
was limited. The period of access to prey did not affect the weight of Day 1 Stage 2 larvae. Larvae fed high densities of
prey for 4 h followed by 20 h of reduced-density diet exhibited the same survival and stage duration as controls that were
continuously fed high-density prey. Our results define sub-optimal diets that can be used experimentally to determine the
nutritional contributions made by naturally-occurring prey organisms during larval development in the two species. In nature,
larvae may satisfy nutritional requirements through periodic encounters with dense prey patches during vertical migrations
by day or night.
Received: 12 August 1997 / Accepted: 5 February 1998 相似文献
15.
Reproduction in birds requires the input of time and energy during discrete breeding phases leading to investment trade-offs
between laying date, clutch size, body mass, and incubation constancy. We investigated costs during incubation by experimentally
enlarging 25 clutches of white-tailed ptarmigan Lagopus leucurus. The experiment was conducted in 2 years, one with harsh weather that forced a natural delay in reproduction. When forced
to delay egg-laying, females began incubation with poorer body condition and foraged more during incubation. Rates of mass
loss during incubation were not affected by clutch enlargement, and did not differ between harsh and benign years; however,
females that were heavier at the start of incubation lost more mass than lighter females. Clutch-enlarged females had reduced
nest attendance compared to control birds in both years and incubation periods increased by up to 2 days relative to controls.
In the harsh year, there was a trend for clutch-enlarged females to have lower nest success, but there was no effect on overwinter
survival. Different behavioral responses by females in the 2 years showed that incubation costs may depend on other factors
such as female quality, food supply, or weather conditions. Incubation is a dynamic period during which birds may adjust energy
balances by varying body condition and food intake.
Received: 28 March 2000 / Received in revised form: 18 August 2000 / Accepted: 2 July 2000 相似文献
16.
Declines in rock-lobster (Jasus lalandii) growth have prompted a re-assessment of their diet, for which we employed an immunological approach (enzyme-linked immunosorbent
assay, ELISA). Antisera were raised against 26 prey species, and their specificity was determined using ELISA. Antibody-binding
was compared using Western blots. The antisera showed high specificity to undigested prey with cross-reactions among antisera
being reduced to <4%. However, cross-reactivity increased to 49% when tested against digested prey, with some antisera even
failing to recognise homologous prey. Sodium dodecylsulphate (SDS) gel electrophoresis demonstrated that excess rock-lobster
digestive enzymes prevented the identification of digested prey by ELISA. However, “inhibition ELISA” (modified ELISA) did
demonstrate species-specific proteins in the digested extracts and could be used to identify digested prey accurately. Nevertheless,
the problem of enzyme interference has to be solved before large-scale screening of rock-lobster diets by ELISA is feasible.
Received: 6 October 1999 / Accepted: 6 June 2000 相似文献
17.
Predation rates and prey selection of the pelagic mysid shrimp, Mysis mixta, were studied experimentally in the northern Baltic Sea in 1998 during their most intensive growth period, from June to October.
Functional responses during 5 months were determined by providing the mysids with a natural zooplankton assemblage, diluted
to several different concentrations. The results show that ingestion rate increased, along with mysid growth, from early summer
to autumn and that saturation level was reached between 400 and 500 μg C l−1. Ingestion rates increased with increasing prey concentration, and sigmoidal curves explained mostly the variation in ingestion
rates (explanatory levels of 86–97%). Prey selection was evident in June, July and August, though weaker during the latter
2 months. Selection differed between the studied months but, generally, copepods were more positively selected than cladocerans.
Rotifers were the main prey during June and July, when mysids were small, while larger mysids fed on copepods and cladocerans.
Of the copepods, Eurytemora affinis was a truly selected species. This study shows that mysids feed on many zooplankton taxa and that they undergo ontogenetic
diet shifts.
Received: 19 July 2000 / Accepted: 19 October 2000 相似文献
18.
Lizards and birds are both popular ”model organisms” in behavioural ecology, but the interactions between them have attracted
little study. Given the putative importance of birds as predators of diurnal lizards, it is of considerable interest to know
which traits (of lizards as well as birds) influence the outcome of a predatory attempt. We studied predation by giant terrestrial
kingfishers (kookaburras, Dacelo novaeguineae: Alcedinidae) on heliothermic diurnal lizards (highland water skinks, Eulamprus tympanum: Scincidae), with particular reference to the role of prey (lizard) size. Our approach was twofold: to gather direct evidence
(sizes of lizards consumed in the field, compared to those available) and indirect evidence (size-related shifts in lizard
behaviour). We quantified the size structure of a natural population of skinks (determined by an extensive mark-recapture
program), and compared it to the sizes of wild lizards taken by kookaburras (determined by analysis of prey remains left at
the birds’ nests). Kookaburras showed size-based predation: they preyed mainly on small and medium-sized rather than large
lizards in the field. However, the mechanism producing this bias remains elusive. It is not due to any distinctive behavioural
attributes (locomotor ability, activity level, habitat usage) of the lizards of the size class disproportionately taken by
the kookaburras. The greater vulnerability of subadult lizards may reflect subtle ontogenetic shifts in ecological and behavioural
traits, but our data suggest that great caution is needed in inferring patterns of vulnerability to predation from indirect
measures based on either the prey or the predator alone. Instead, we need direct observations on the interaction between the
two.
Received: 30 May 2000 / Revised: 29 July 2000 / Accepted: 26 August 2000 相似文献
19.
Jorge E. Rabinovich Martín Torres Jordá C. Bernstein 《Behavioral ecology and sociobiology》2000,48(4):308-315
Telenomus fariai is a gregarious endoparasitoid of the eggs of several species of Triatominae (Hemiptera) with a high degree of sibmating:
males fertilize their sisters inside the host egg before emergence or emerge first and copulate with their sisters as these
emerge. Our results show that, when laying alone, T. fariai behaves adaptively, minimizing offspring mortality and conforming to the prediction of local mate competition (LMC) theory
by laying a single male, which is sufficient to fertilize all the sisters. When more than one wasp was placed with one host,
sex ratios still conformed to LMC predictions but, despite the decreasing number of eggs laid per wasp, clutch size could
not be completely adjusted to avoid mortality. This is not surprising, as superparasitism is rare in the field. Offspring
production was independent of the contacts between conspecifics but was affected by the number of mothers laying on a single
host egg. The sex of the progeny was precisely determined: a female produced one male per clutch when laying on both unparasitized
or previously parasitized hosts. On the other hand, a mother produced less daughters when superparasitizing. Under crowded
conditions, the number of eggs laid per female wasp and per host decreased as the number of mothers increased. Developmental
mortality also increased with the number of T. fariai eggs per host, determining a maximum of approximately 14 emerged adults. Host resources per individual affected male and
female adult size with similar intensity, and male adult mortality was slightly higher than that for females. These results,
and previous findings, suggest that T. fariai attains Hamiltonian sex ratios by laying one male and a variable number of females, and that the detection of chemical marks
left by conspecifics provides information on the number of foundresses sharing a patch.
Received: 4 February 2000 / Received in revised form: 19 April 2000 / Accepted: 20 May 2000 相似文献
20.
A. Peters L. B. Astheimer C. R. J. Boland A. Cockburn 《Behavioral ecology and sociobiology》2000,47(6):438-445
Testosterone has been proposed as a physiological link between the level of sexual signalling and male condition. Bright plumage
is one of the most noticeable sexual signals and is often used by females as a basis for mate choice. Yet bright male plumage
is not necessarily testosterone dependent. We investigated the role of testosterone in the moult into seasonal nuptial plumage
in male superb fairy-wrens. Early pre-nuptial moult is under intense intersexual selection and males can acquire the bright
plumage any time between autumn and the next spring. Testosterone was always undetectable or very low in males in dull eclipse
plumage. During the pre-nuptial moult, both the number of males with detectable testosterone and average testosterone levels
increased sharply. High testosterone was more correlated with nuptial plumage than with presence of the cloacal protuberance
(indicative of sperm storage). Subcutaneous testosterone implants always induced the pre-nuptial moult within 2–3 weeks after
implantation, even well outside the natural time range of moulting. Moreover, removal of the implants before the nuptial plumage
was completed, arrested the moult process. The evidence suggests that development of the nuptial plumage is testosterone dependent,
although we cannot exclude that testosterone exerts its action after conversion to a metabolite such as oestrogen. Once the
nuptial plumage was completed, all males maintained substantially elevated testosterone, sometimes months before the onset
of breeding. These high levels could be necessary to maintain the plumage, and/or are involved in courtship displays. The
results are discussed with respect to potential costs involved in acquiring and maintaining the nuptial plumage.
Received: 17 January 2000 / Received in revised form: 24 February 2000 / Accepted: 25 February 2000 相似文献