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1.
Alison M. Muldal J. David Moffatt Raleigh J. Robertson 《Behavioral ecology and sociobiology》1986,19(2):105-114
Summary Nestling feeding by males is less common among birds with polygynous mating systems than in monogamous species, because of the pronounced trade-off between parental behavior and the attraction of additional mates. In this study, however, we found that male red-winged blackbirds (Agelaius phoeniceus) commonly assisted females in feeding nestlings in several Ontario marshes. Male parental care was additional to that provided by females, and it significantly enhanced the fledging success of nests (Table 2). Male redwings did not help to feed all nests on their territories: primary and secondary nests were much more likely to receive male parental care than tertiary and later nests. Contrary to expectation, male parental care was not restricted to the nests of primary females: a greater proportion of secondary than primary nests were assisted (Tables 4a and b). The presence of new females settling on the territory at the same time that a resident female had nestlings, resulted in males deferring parental care until a later brood. This suggests that males trade off the recruitment of females against parental care to an existing brood. Although the number of nestlings fledging from a male's territory was strongly influenced by the number of females in the harem, males could additionally increase their reproductive success by feeding nestlings in one or more nests on their territories (Fig. 2). The reproductive success of females was significantly enhanced by male assistance in feeding nestlings (Table 3). However, those females not receiving male assistance on territories of feeding males did not suffer a significantly reduced reproductive success in comparison to females on territories of non-feeding males (Table 2). Males varied considerably in the quality of brood care given. We therefore suggest that the quality of male parental care may be a factor considered by females in choosing a breeding situation. 相似文献
2.
James V. Briskie Robert Montgomerie Tarmo Põldmaa Peter T. Boag 《Behavioral ecology and sociobiology》1998,43(3):181-190
In species where females copulate with more than one male during a single breeding attempt, males risk investing in offspring
that are not their own. In the polygynandrous Smith's longspur (Calcarius pictus), females copulate sequentially with one to three males for each clutch of eggs and most of these males later assist in feeding
the young. Using multilocus DNA profiling, we determined that there was mixed paternity in >75% of broods (n=31) but that few offspring (<1% of 114 nestlings) were sired by males outside the polygynandrous group. Male feeding rate
increased significantly with the number of young sired, with males siring four nestlings feeding the brood at double the frequency
of males siring only a single nestling. However, male Smith's longspurs appear to show a graded adjustment of paternal care
in response to paternity only when other males are available to compensate for reduced care: feeding rate did not vary in
relation to paternity when only one male provisioned young at the nest. There was no evidence that males could recognise their
own offspring within a brood and feed them preferentially. The number of offspring sired by each male was significantly correlated
with the number of days spent copulating with the attending female: on average, a male sired one offspring for every 2 days
of copulatory access. If males use their access to females to estimate paternity (and thereby decide on their subsequent level
of parental investment), a positive relationship is expected between the amount of female access and the subsequent feeding
rate to the nestlings. Nonetheless, male feeding effort was only weakly correlated with female access and more study is needed
to determine how males estimate their paternity in a brood.
Received: 1 June 1997 / Accepted after revision: 1 April 1998 相似文献
3.
Bruce E. Lyon Robert D. Montgomerie Linda D. Hamilton 《Behavioral ecology and sociobiology》1987,20(5):377-382
Summary We experimentally removed males from a random sample of 14 snow bunting (Plectrophenax nivalis) pairs to determine the influence of male parental care on reproductive success. Widowed females increased their rate of food delivery to nestlings by increasing their feeding visit rate but not their load size. However, Widows were only able to achieve 73% of the food delivery rate of Control pairs and, as a result, they raised fewer offspring of lower quality (i.e. lower mass at fledging). Total brood mass raised by Widows was only 55% of that of Control pairs. Thus, in the year of our experiment, male parental care in the nestling period almost doubled the reproductive success realized from a brood. Our experiment, however, was done in a year of poor food availability and data from the previous year, when food supply was higher, indicate that males may not always be so important. Since nestling food supply appears to be unpredictable at the time of pair formation, we suggest that monogamy is a bet-hedging strategy in case of poor food availability. As a consequence the importance of male parental care in some years may explain why snow buntings are almost always monogamous. 相似文献
4.
Giuseppe Boncoraglio Roberta Martinelli Nicola Saino 《Behavioral ecology and sociobiology》2008,62(5):729-738
In diverse taxa, offspring solicit parental care using complex displays, which may evolve as reliable signals of condition
or as mechanisms to manipulate parental investment. Differential sex allocation may therefore result from adaptive parental
decisions or sex-related variation in competitive ability or because of sex-related asymmetries in kin selection. Under normal
food provisioning, female barn swallow (Hirundo rustica) nestlings begged more loudly but did not receive more food than male nestlings. After food deprivation, begging call loudness
of males but not females increased. Begging loudness positively predicted the number of feedings received by the nestlings,
and males gained more mass than females after food deprivation. Male nestlings are more severely affected by chronic food
reduction and may therefore accrue a larger benefit compared to females by increasing their food intake under short-term conditions
of food scarcity. These results suggest that either females do not increase begging intensity to favour male broodmates which
are more vulnerable to prolonged food stress, or that males prevail in scramble competition despite being similar in size
to females. 相似文献
5.
Do males and females differ in the feeding of large and small siblings? An experiment with the bluethroat 总被引:3,自引:0,他引:3
Per T. Smiseth Trond Amundsen Lars T. T. Hansen 《Behavioral ecology and sociobiology》1998,42(5):321-328
Males and females have been reported to differ in their feeding of large and small siblings in several species of birds.
According to recent hypotheses, this phenomenon may be related to a sexual conflict over avian hatching patterns. We designed
an experiment to test for the existence of such a sex difference by manipulating nestling size hierarchies of the bluethroat
(Luscinia s. svecica) in two directions; half the broods were “asynchronized” to yield large size-differences within broods and the other half
were “synchronized” to yield small size-differences. In all broods, nestlings were categorized as being either large or small
according to body mass. We recorded male and female food distribution by video early (day 4 after hatching) and late (day
8) in the nestling period. Males and females did not differ in their distribution of food among different-sized nestlings.
With large size-differences, both males and females fed large nestlings nearly twice as often as small ones. In contrast,
when the size-differences were small, food was more evenly distributed among nestlings. Early in the nestling period, males
fed more nestlings during each feeding visit than did females. Our finding that male and female bluethroats do not differ
in the feeding of large and small siblings is in contrast to most previous studies. Variation in costs and benefits to males
and females from feeding different-sized nestlings, and restrictions to parental choice due to nestling interactions, may
explain interspecific variation.
Received: 27 June 1997 / Accepted after revision: 26 January 1998 相似文献
6.
Emlen and Oring (1977) suggested that monogamy in birds is maintained because of the need for strict biparental care. A corollary of their suggestion is that paternal care should decrease under conditions of high food abundance. An alternative is that paternal care would increase if males take advantage of the higher food abundance by trying to reduce the length of the nestling feeding period. We tested these two ideas using yellow warblers (Dendroica petechia) by providing some pairs with supplemental food, thereby reducing the importance of biparental care. However, the extra food did not decrease paternal effort, nor did it increase it (Fig. 2). Early in the nestling period experimental females brooded more but visited their nestlings less than did control females, but later, when brooding times decreased, experimental females fed their nestlings more than did control females (Fig. 3). There were no significant differences in nestling survival (Fig. 5), but nestlings in the control treatment were larger and heavier up to 6 days old (Fig. 6). The main effect of supplemental food was on maternal, not paternal behaviour. Models of biparental care assume interdependence between the parental effort of both parents. In this species, however, males and females provide for their brood independently from each other. 相似文献
7.
Summary We investigated the division of labor in male and female tree swallows by measuring the rate of food delivery to nestlings at 36 nests. By observing natural nests and performing brood manipulations we found that males and females divided the feeding duties about equally and responded similarly to changes in brood size and age. Feeding rate was most highly correlated with brood mass. Manipulation and removal experiments showed that increased feeding rates could be elicited, but only for limited periods of time. Male and female tree swallows could only partially compensate in feeding nestlings when mates were removed. This, along with the higher mortality in enlarged broods and in those raised by single parents, indicates that both male and female are required to raise an entire brood to fledging. We argue that this requirement contributes to the absence of mate guarding and the maintenance of monogamy in the tree swallow. 相似文献
8.
Oscar Vedder Arjan L. Dekker G. Henk Visser Cor Dijkstra 《Behavioral ecology and sociobiology》2005,58(4):429-436
Allocation of parental investment is predicted to be equal at the population level between both sexes of offspring, and should lead to sex ratio biases in species that exhibit a sex-difference in parental care. Sex-differences in parental care are rarely quantified. We measured daily energy expenditure in free-living nestlings of the extremely sexually size dimorphic European sparrowhawk (Accipiter nisus), using the doubly labelled water method. These data were combined with measured growth characteristics to estimate daily and total metabolised energy intake of male and female young during the nestling stage. Females reached an asymptotic body mass 1.6 times higher than males. This resulted in a total metabolised energy an estimated 1.4 times higher for the nestling stage. Furthermore, we observed a decline in daily metabolised energy with an increase in brood size, which was significantly stronger for females than for males. These results are discussed in the context of Fishers equal allocation theory. Empirical evidence of a sex ratio bias at the end of parental care, with an overall excess of males, is lacking in this species. Consequently, our data do not support the idea of equal allocation between the sexes. The observed sex difference in daily metabolised energy in response to brood size may give scope for sex ratio bias at the level of the individual brood. 相似文献
9.
We used a brood-size manipulation to test the effect of rearing environment on structural coloration of feathers grown by
eastern bluebird (Sialia sialis) nestlings. Ultraviolet (UV)-blue structural coloration has been shown to be sexually selected in this species. Our experimental
design took advantage of the growth of UV-blue wing feathers in nestlings that are retained as part of the first nuptial plumage.
We cross-fostered nestlings to create enlarged and reduced broods with the purpose of manipulating parental feeding rates
and measured the effect on nestling growth and plumage coloration. Brood size influenced feeding rates to offspring, but the
effect varied with season. In general, male nestlings reared in reduced broods were fed more often, weighed more, and displayed
brighter structural plumage compared to nestlings reared in enlarged broods. Female nestlings appeared to experience less
adverse affects of brood enlargement, and we did not detect an effect of brood-size manipulation on the plumage coloration
of female nestlings. Measures of plumage coloration in both males and females, however, were correlated to hatching date and
nestling mass during feather development. These data provide empirical evidence that environmental quality can influence the
development of the blue structural coloration of feathers and that males may be more sensitive to environmental fluctuations
than females. 相似文献
10.
Juan Moreno Santiago Merino Jaime Potti Ana de León Rosa Rodríguez 《Behavioral ecology and sociobiology》1999,46(4):244-251
We manipulated parental work load without changing brood size in a population of pied flycatchers Ficedula hypoleuca by removing two primaries (7 and 9) from each wing of females, thus reducing wing area and increasing flight costs. At other
nests, we offered supplementary food in the form of live mealworms (10–20 g daily from hatching) to reduce brood demand and
thus parental foraging costs. Other nests were left as controls. The daily energy expenditure of females feeding 12-day-old
nestlings was measured with doubly labelled water D2
18O. Females in both treatments expended the same amount of energy, fed at the same rate and had similar body masses to birds
in the control group. No effect of treatment on male mass and feeding effort was detected. More nestlings, however, died in
nests of handicapped females. Nestlings of handicapped females had significantly lower body mass and haematocrit values than
nestlings in food-supplemented nests, with nestlings in control nests occupying an intermediate position. The effects of both
treatments on nestling mass, haematocrit values and mortality rates were only noticeable in nests infested with mites. Maternal
energy expenditure is apparently constrained and offspring pay the costs imposed by reduced provisioning rate or increased
demand caused by ectoparasites, while receiving benefits when food supply improves. The presumption that avian reproductive
costs derive from changes in a flexible energy output may not be met in many cases.
Received: 24 October 1998 / Received in revised form: 15 March 1999 / Accepted: 26 April 1999 相似文献
11.
Feeding frequency and parental division of labour in the double-brooded great tit Parus major 总被引:2,自引:0,他引:2
Henrik G. Smith Hans Källander Kristina Fontell Martin Ljungström 《Behavioral ecology and sociobiology》1988,22(6):447-453
Summary We studied the relative contribution of each sex and total effort expended in feeding nestlings in the great tit Parus major in relation to artificially altered brood size. A recent model suggests that feeding frequency should reflect the optimal trade-off between parental and fledgling survival, the former being negatively, the latter positively, influenced by high feeding frequencies. In both sexes weight loss was linearly related to feeding frequency. Since fledgling survival increases with nestling weight, the conditions of this model are fulfilled. However, in contrast to the predictions of the model, the total feeding frequency for both sexes combined did not differ between control and enlarged broods, but was lower for reduced ones. This outcome was not the result of a physiologically related inability of the parents to increase their delivery rate. Instead, we suggest that parents with enlarged broods could not find sufficient amounts of prey large enough to be economically worth transporting to the nest. Differences in brood-provisioning rates between the sexes may arise because costs and benefits of feeding nestlings may differ. Females lost more weight than males during the nesting period, but maintained a relatively higher weight during the incubation period. The relationship between weight loss and feeding frequency was similar for both sexes. Male and female brood-feeding frequency was related to brood size in a similar way. This is discussed in light of the great tit's mating system and the fact that the great tit is facultatively double-brooded. 相似文献
12.
The extent to which male birds in polygynous species with biparental care assist in nestling feeding often varies considerably
between nests of different mating status. Both how much polygynous males assist and how they divide their effort between nests
may have a profound effect on the evolution of mating systems. In this study we investigated how males in the facultatively
polygynous European starling Sturnus vulgaris invested in their different nests. The amount of male assistance affected the quality of the offspring. Polygynous males
invested as much as monogamous males, but divided their effort asymmetrically between nests, predominantly feeding nestlings
of first-mated (primary) females. Although females partly compensated for loss of male assistance, total feeding frequency
was lower at primary females’ nests than at monogamous females nests. Secondary females received even less assistance with
nestling rearing, and the extent to which males assisted decreased with the length of the interval between the hatching of
the primary and secondary clutches. These results are contrasted with those from a Belgian populations of starlings with a
much more protracted breeding season and thus greater opportunities for males to attract additional mates during the nestling
rearing period. The results show that both the “defence of male parental investment model” and the “asynchronous settlement
model” have explanatory power, but that their validity depends on the potential length of the breeding season.
Received: 21 July 1995/Accepted after revision: 13 July 1996 相似文献
13.
Replacement males in the western bluebird: opportunity for paternity, chick-feeding rules, and fitness consequences of male parental care 总被引:2,自引:0,他引:2
In western bluebirds (Sialia mexicana), most pairs remain together for life and share equally in post-hatching parental care. We removed resident males of socially
monogamous pairs during laying and after clutch completion to examine chick-feeding rules used by replacement males and current
and future fitness consequences of paternal care. Replacement males were not infanticidal and 7 (47%) fed nestlings. Feeding
replacement males and the females they joined fed at rates similar to controls. Females without a feeding replacement male
compensated by feeding more themselves so that overall feeding rates were not compromised, but they reduced their brooding
time. Unlike assisted females, unassisted females exhibited reduced nesting success and their 14-day-old chicks weighed less
than controls. Field metabolic rates of unassisted females were 17% higher than those of control females, but the difference
was not statistically significant. Older females were better able to raise young without the male's help than were yearling
females. Female condition was not affected by male provisioning and unassisted females were as likely to survive to the next
breeding season as assisted females. We found no future benefits of provisioning by replacement males; those that fed were
no more likely to breed with the female on her subsequent attempt than were males that did not feed, and subsequent clutch
sizes were not reduced for females rearing young without the male's help. These experiments suggest that male parental care
increases nesting success in western bluebirds and that replacement males use an all-or-none rule to determine whether or
not to feed chicks: if they are present during the fertile period they feed at typical rates; if they are not, they usually
do not feed at all. Because chick-feeding by males is tied to opportunity for paternity, influences success in the current
nest, and does not affect the male's future breeding success, it appears to be parental rather than mating effort.
Received: 8 May 1998 / Accepted after revision: 23 July 1998 相似文献
14.
Female choice and the evolution of the conspicuous plumage coloration of monogamous male great tits 总被引:6,自引:0,他引:6
K. J. Norris 《Behavioral ecology and sociobiology》1990,26(2):129-138
Summary The conspicuous male plumage coloration of many avian species is often regarded as the result of sexual selection through female choice. In general terms such plumage characters may evolve in monogamous species if males bearing them pair with high quality females and so reproduce more successfully than males lacking the character. Male great tits have a conspicuous, central black breast stripe which varies in size between individuals. The stripe is also present in the female although it is smaller in size. Male great tits with large stripes paired with females which laid large clutches. Furthermore, in one of three years, females paired with such males commenced breeding earlier in the season than other females. Individual females were significantly more consistent in their clutch size and laying date between years than were nesting boxes. Males with large stripes paired with females which had previously laid a large clutch. Although there was evidence that territory quality may affect female reproductive success by influencing nesting success and nestling quality, there was no significant relationship between the stripe size of a male and the quality of his territory. Therefore, the results suggest that female great tits are choosing the characteristics of the male rather than the quality of his territory. The evidence thus suggests that female choice may be important in the evolution of male secondary sexual characteristics in great tits. 相似文献
15.
I. Nishiumi Satoshi Yamagishi Hiromi Maekawa Chikashi Shimoda 《Behavioral ecology and sociobiology》1996,39(4):211-217
In many polygynous animals, parents invest more heavily in individual sons than in daughters. However, it is unclear if these
differences in investment are a consequence of sex differences in the demand of offspring related to sexual size dimorphism
or a consequence of parental manipulation. Here, we report on parental food delivery frequency in relation to brood size and
brood sex ratio in a wild population of polygynous great reed warblers Acrocephalus arundinaceus. We used the polymorphic microsatellite loci on the Z chromosome to sex chicks. We found that paternal feeding frequency
(times/h per nest) increased not with brood size, but with the proportion of males in the brood, although the demand per nest
was more closely related to brood size than to brood sex ratio. Additionally, the increase in rate of paternal feeding frequency
in relation to the brood sex ratio was much higher than the increase in rate of nestling food demands. Maternal feeding frequency
was independent of both brood size and brood sex ratio. These results strongly suggest that fathers preferentially invest
in their sons. We propose that parents can afford sex-biased parental care in animals in which food provisioning is enough
for all offspring to survive.
Received: 22 January 1996/Accepted after revision: 30 June 1996 相似文献
16.
Nathaniel T. Wheelwright Cheryl B. Schultz Peter J. Hodum 《Behavioral ecology and sociobiology》1992,31(4):279-289
Summary To determine the effects of male mating status on female fitness, we compared the reproductive success, survival, and future fecundity of female Savannah sparrows (Passerculus sandwichensis) mated to monogamous vs. polygynous males in a 5-year study on Kent Island, New Brunswick, Canada. The proportion of males with more than one mate varied from 15 to 43% between years and sites. Polygynous and monogamous males fledged young of equal size in every year of the study. Females who shared paternal care with other females laid as many eggs per clutch and clutches per season as monogamously mated females. In most years polygynously mated females showed no delay in laying a second clutch, and they suffered no reduction in fecundity the following year. Recruitment of a female's offspring into the breeding population was generally independent of her mating status. Fitness costs of being mated to a polygynous male were only apparent in one year of the study, during which females mated to polygynous males had higher over-winter mortality than those mated to monogamous males. That same year, young raised by polygynous males were only one-third as likely to survive to reproductive maturity (as inferred by returns) as those raised by monogamous males. A male's mating status had no effect on his own survivorship. A male's mating status did not necessarily reflect his contributions to raising nestlings, which may partially explain why monogamously and polygynously mated females had equal fitness. At 35 nests the proportion of food deliveries brought by individual males varied from 0 to 75%; on average, males brought fewer than 30% of all food deliveries. Yet parental care by polygynous males was no less than that of monogamous males, at least at the nests of their primary females. Secondary females tended to receive less male assistance during the nestling stage, but their reproductive success was indistinguishable from that of primary females. Females feeding young without male assistance made as many food deliveries/h as did pairs in which males brought at least 30% of all food deliveries. Unassisted females did not suffer diminished fledging success or produce smaller fledglings. The benefits of polygyny for male Savannah sparrows are clear: polygynous males recruit more surviving offspring into the breeding population than monogamous males. The fitness of females, on the other hand, appears to be unaffected by whether their mate was monogamous or polygynous except in occasional years. Polygyny may be maintained in this population by the constraints of a female-biased sex ratio, the inability of females to predict a male's paternal care based on his morphology or behavior, the poor correlation between a male's mating status and his assistance at the nest, and inconsistent natural selection against mating with a polygynous male.
Correspondence to: N.T. Wheelwright 相似文献
17.
Summary Several recent studies have questioned whether the presence and activities of monogamous male birds are of value to their young during the nesting attempt. We addressed this issue in house wrens (Troglodytes aedon) by removing males early in the nestling stage. In one of four periods survivorship among experimental nestlings was 63% lower than among control nestlings. In the other periods survivorship was about equal in experimental and control nests indicating that in this species the male's activities may only benefit his nestlings during unfavorable periods. We summarize the results of 15 other male removal studies, concluding that when males appear to be helping, their absence usually results in decreased survival of young whereas when the males render little apparent care their absence does not decrease survival of the young. A possible exception to this generalization, illustrated by our study and others, is that during the nestling stage of many altricial species, the female appears able to raise the young about as well without the male as with him, except in poor periods. A male caring for his nestlings during good periods may benefit by maintaining his mate's health for the next nesting attempt or by insuring her willingness to mate with him again. Alternatively, it may cost males so little to help during good periods, and benefit them so much during poor periods, that there has been little selective pressure for them to assess conditions and vary their level of care accordingly. A series of more specific predictions about which males are likely to be of greatest, and least, value to their nestlings is presented. Male care after young leave the nest has not been well studied, but is probably substantial in many species, and warrants attention in future studies. 相似文献
18.
Within a family there are conflicts of interest between parents and offspring, and between male and female parents, over the
supply of parental care. The observed pattern of parental care is the outcome of negotiations within the family, and may be
influenced by environmental factors such as food abundance. We experimentally increased food supply to ten Tengmalm’s owl
(Aegolius funereus) nests from hatching to fledging, mimicking natural cached prey. Ten un-supplemented nests served as controls. Parents and
offspring were fitted with radio-tags. Food provisioning by parents was measured both in the (1) mid- and (2) late nestling
stage and in the (3) early and (4) late post-fledging stage. In response to food supplementation, both males and females reduced
food provisioning, but the effect was more pronounced in females. Females generally contributed much less to food provisioning
than males, and food supplementation increased the difference between the sexes. Mass loss during the brooding stage was substantially
lower for supplemented than for control females. Food supplementation did not improve offspring survival, and had no effect
on body measurements of nestlings. In conclusion, parents of both sexes used the increased food supply to reduce the costs
of caring for their current offspring, but females responded more strongly than males. 相似文献
19.
Amanda J. Gilby Enrico Sorato Simon C. Griffith 《Behavioral ecology and sociobiology》2012,66(11):1519-1529
Differential resource allocation by females across the laying sequence has been hypothesised as a mechanism through which females could either compensate nestlings that hatch last in asynchronous broods or promote brood reduction. In this study we artificially incubated eggs and cross-fostered offspring to manipulate nestlings’ position in the hatching order, to identify whether the competitive ability of nestlings is dependent on position in the laying sequence. In both control and experimentally reversed broods, first hatched chicks had a higher survival than last hatched siblings. Yet, nestlings that hatched from eggs laid in the second half of a clutch begged with a greater intensity than nestlings hatched from eggs laid in the first half of a clutch. In natural broods, the greater begging competitiveness of nestlings from later-laid eggs led to a moderation of sibling competition and these nestlings achieved the same body size and weight as nestlings from eggs laid in the first half of the clutch. The lack of a substantial difference in the size and condition of surviving nestlings in respect to laying order suggests that differential resource allocation across the egg-laying sequence partially compensates for hatching last in asynchronous broods and reduces the negative effects of the nestling size hierarchy. The effect of laying order, brood size and experimental treatment also differed for male and female nestlings. Our study highlights the need to be aware of the complex and subtle effects of nestling sex and laying sequence when investigating genetic and environmental influences on individual fitness. 相似文献
20.
The cost of parental care and egg cannibalism in the river bullhead,Cottus gobio L. (Pisces,Cottidae) 总被引:4,自引:0,他引:4
Summary Male river bullheads guard and care for egg masses during a single brood cycle every breeding season. A study of two bullhead populations demonstrated that nesting males show a strong reduction in food intake rate and that their physical condition deteriorates during parental care. The estimated weight loss for the average guarding male was 18.8% in one population and 13.5% in the other. This could in part be responsible for the peak of male mortality observed during the second part of the breeding season. A high incidence of egg cannibalism was observed in males guarding eggs. Analysis of the developmental stage of individual egg masses demonstrated that heterocannibalism is very rare in this species and that the observed rate of egg cannibalism is mainly due to guarding males preying upon their own eggs (filial cannibalism). In both populations the frequency of filial cannibalism was negatively correlated with the male's chance of getting other food items. The probability of a male cannibalizing its own eggs was also significantly influenced by the time elapsed since the beginning of parental care. The observed limited cannibalism of progeny in the river bullhead cannot be explained as a male's strategy for obtaining energy to be used in subsequent brood cycles, as suggested for other fishes which show filial cannibalism. Rather, it can be interpreted as a behaviour aimed at avoiding the risk of dying of starvation before the eggs hatch. The observed criteria of female mate choice, i.e. a preference for males in good physical condition and for males that already have eggs in their nests, are consistent with the prediction of Rohwer's filial cannibalism theory, although other hypotheses cannot be excluded. 相似文献