While the function of ornaments shaped by sexual selection is to attract mates or drive off rivals, these signals may also evolve through social selection, in which the social context affects the fitness of signallers and receivers.... more
While the function of ornaments shaped by sexual selection is to attract mates or drive off rivals, these signals may also evolve through social selection, in which the social context affects the fitness of signallers and receivers. Classical 'mate choice' experiments often reveal preferences for ornaments, but few studies have considered whether these are strictly sexual or reflect general social preferences. Indeed, an alternative possibility is that ornaments evolve through 'non-sexual social selection' (hereafter 'social selection'). We examined the role of ornamentation (yellow ventral patch) and familiarity (individuals recognize group mates with which they have had previous interactions) on mate choice (opposite-sex stimuli preference) and social choice (same-sex stimuli preference) in both male and female white-eyed bulbuls (Pycnonotus xanthopygos). In the mate choice test, females preferred unfamiliar males with increased yellow. There were no biologically important differences in male preferences based on familiarity or intensity of patch colour. In the social choice test, females preferred to associate with familiar females. Males preferred to associate with familiar males but also preferred to associate with less ornamented males. Our results suggest that ornamentation and familiarity are important features, playing different roles in males and females, in both social and sexual selection processes.
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Research Interests: Breeding, Ecology, Population Dynamics, Hungary, Female, and 6 moreAnimals, Male, Oecologia, Fertilization, Ranidae, and Rana temporaria
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While it is well established that females prefer to mate with well-ornamented males, the influence of perceptive and cognitive processes on the expression of female mate choice is still poorly known. It has been suggested that the female... more
While it is well established that females prefer to mate with well-ornamented males, the influence of perceptive and cognitive processes on the expression of female mate choice is still poorly known. It has been suggested that the female perception of a male's attractiveness is not absolute, but depends on the other males with which he is compared that have been previously encountered (comparative evaluation). We investigated whether mate preference in bearded reedlings (Panurus biarmicus) is dependent on or independent of social context in relation to two different traits: beard and tail lengths. Each female had a choice between two to three males with different modifications of beard and tail. For each female, three different experiments were conducted (one binary and two trinary tests). We found that when females are presented with options that vary antagonistically with respect to two ornaments (binary test), some individuals prefer one trait while others the other trait. This indicates that in our bearded reedlings population exists a mate preference polymorphisms. Moreover, we found that the presence of a third stimulus, irrespective of the initial preference, reduced the strength of the initial preference - what we can call a "preference dilution effect." Our results suggest that the female's choice may be constrained by her cognitive abilities when she is simultaneously presented with several options varying for two uncorrelated traits.
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Aim: We tried to find out breeding biology and behavioral strategies of the YellowventedBulbul, Pycnonotus xanthopygos, both in the field and in captivity Methods: Campus of Akdeniz University and its vicinity were selected to field... more
Aim: We tried to find out breeding biology and behavioral strategies of the YellowventedBulbul, Pycnonotus xanthopygos, both in the field and in captivity
Methods: Campus of Akdeniz University and its vicinity were selected to field study.During the field study, possible territorial areas of the species were checked daily to
find nests and to observe behavioral activities at the beginning of March to end ofAugust in 2013. Each nest was observed every second days to get breeding data.
Adults were captured by using mist nests and ringed to individual identification. Ringed individuals were measured to classify individual quality. At the end of breeding season
of the species, we captured individuals from Çakırlar, 20 km far from Antalya, districtand put them to aviaries to study behavior of the species in captivity .
Results: Territorial and nesting tree features of the species were determined. It was found out that pairing was formed at the beginning of the breeding season and both
male and female were selected territory and females decided to nesting tree. Male and female were built nest together and they were showed parental care till fledglings can survive alone at the territory. A total of 35 nests were found at the campus during first breeding season. Of the 35 nests; 16 were abandoned and 6 were failed. The breeding
success of the species by clutch size was 3 ± 0.2 (2-4), hatching was % 96.6 ± 3.3 and fledgling was % 90,6 ± 2.1 (n:11). Captured individuals are adjusted to the aviaries and
are ready to behavioral experiments. .
Conclusion: Although P. xanthopygos is considered as an adapted species to the urban ecosystems, result of the first breeding season showed that 45 % of the nests were
abandoned by human activities. This indicate that P. xanthopygos is very sensitive to human activities. The question is that how P. xanthopygos cope with human activities and expand its distribution zone. We will conduct behavioral experiments in field and captivity to understand this phenomenon.
Key words: Yellow-vented bulbul, Pycnonotus xanthopygos, behaviour of birds,ethology, parental care, ornament
Methods: Campus of Akdeniz University and its vicinity were selected to field study.During the field study, possible territorial areas of the species were checked daily to
find nests and to observe behavioral activities at the beginning of March to end ofAugust in 2013. Each nest was observed every second days to get breeding data.
Adults were captured by using mist nests and ringed to individual identification. Ringed individuals were measured to classify individual quality. At the end of breeding season
of the species, we captured individuals from Çakırlar, 20 km far from Antalya, districtand put them to aviaries to study behavior of the species in captivity .
Results: Territorial and nesting tree features of the species were determined. It was found out that pairing was formed at the beginning of the breeding season and both
male and female were selected territory and females decided to nesting tree. Male and female were built nest together and they were showed parental care till fledglings can survive alone at the territory. A total of 35 nests were found at the campus during first breeding season. Of the 35 nests; 16 were abandoned and 6 were failed. The breeding
success of the species by clutch size was 3 ± 0.2 (2-4), hatching was % 96.6 ± 3.3 and fledgling was % 90,6 ± 2.1 (n:11). Captured individuals are adjusted to the aviaries and
are ready to behavioral experiments. .
Conclusion: Although P. xanthopygos is considered as an adapted species to the urban ecosystems, result of the first breeding season showed that 45 % of the nests were
abandoned by human activities. This indicate that P. xanthopygos is very sensitive to human activities. The question is that how P. xanthopygos cope with human activities and expand its distribution zone. We will conduct behavioral experiments in field and captivity to understand this phenomenon.
Key words: Yellow-vented bulbul, Pycnonotus xanthopygos, behaviour of birds,ethology, parental care, ornament
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Because parental care is costly, a sexual conflict between parents over parental investment is expected to arise. Parental care behavior is an adaptive decision, involving trade-offs between remating, and consequently desertion of the... more
Because parental care is costly, a sexual conflict between parents over parental investment is expected to arise. Parental care behavior is an adaptive decision, involving trade-offs between remating, and consequently desertion of the brood, and continuing parental effort. If the main advantage of desertion is remating, then this will be a time constraint, because the deserting individual will require a certain minimum period of time to breed again in the same breeding season. So, a short breeding season should force certain individuals to desert the first brood to have enough time to successfully complete their second breeding attempt. The rock sparrow, Petronia petronia, is an unusual species in which brood desertion can occur in both sexes and the breeding season is quite short so it is a good species to investigate the role of time constraint on brood desertion. For 3 years, I investigated the brood desertion modality of the rock sparrow. Then, for 2 years, I removed a group of experimental nest boxes during the autumn. Later, I re-installed the experimental nest boxes after the start of the breeding season (2 weeks after the first egg was laid), mimicking a shortening of the breeding season for the (experimental) pairs that used experimental nest boxes. I found that in the experimental pairs, the percentage of deserting individuals was significantly higher than in the control groups, and the deserting individuals were older females. This experiment adds to our knowledge of timing of reproduction effects on individual decisions to desert by showing that a short and delayed breeding season may have different effects on males and females. To my knowledge, this is the first experimental study that demonstrates a direct link between time constraint and brood desertion.
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Research Interests: Breeding, Ecology, Population Dynamics, Hungary, Female, and 6 moreAnimals, Male, Oecologia, Fertilization, Ranidae, and Rana temporaria
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ABSTRACT 2013): Does egg colouration signal female and egg quality in reed warbler (Acrocephalus scirpaceus)?, Ethology Ecology & Evolution, 25:2, 129-143 This article may be used for research, teaching, and private study... more
ABSTRACT 2013): Does egg colouration signal female and egg quality in reed warbler (Acrocephalus scirpaceus)?, Ethology Ecology & Evolution, 25:2, 129-143 This article may be used for research, teaching, and private study purposes. Any substantial or systematic reproduction, redistribution, reselling, loan, sub-licensing, systematic supply, or distribution in any form to anyone is expressly forbidden. The publisher does not give any warranty express or implied or make any representation that the contents will be complete or accurate or up to date. The accuracy of any instructions, formulae, and drug doses should be independently verified with primary
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In many animal species ornaments and display behaviours are used together in intersexual communication. Few studies, however, have simultaneously explored how the static and dynamic components interact. We examined the significance of... more
In many animal species ornaments and display behaviours are used together in intersexual communication. Few studies, however, have simultaneously explored how the static and dynamic components interact. We examined the significance of behaviour (e.g. dominance status) in comparison with beard length for the mate choice process in a bird species, the bearded reedling, Panurus biarmicus. In choice experiments, females were confronted with two males of varying beard length (artificially shortened or elongated) and status (dominant/subdominant). The results suggest that female choice is primarily based on beard length whereas dominance seems to be less important. Our results indicate that the beard length plays an important role in female choice in this species, as previously reported. Nevertheless, dominance status has a slight complementary effect. Beard length and behaviour seem to inform the female about the same aspect of male condition but with a different error probability. However, additional studies in which display rates and song properties are directly manipulated are needed.
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Pair bond duration and age are suggested to be important determinants for reproductive success in long-term monogamous pair bonding. These two effects are generally difficult to separate, however, and experimental approaches are scarce.... more
Pair bond duration and age are suggested to be important determinants for reproductive success in long-term monogamous pair bonding. These two effects are generally difficult to separate, however, and experimental approaches are scarce. We experimentally examined the role of the extended pair bond period, controlling for age and experience, in the bearded reedling, Panurus biarmicus. In this species pairs form in juvenile flocks and usually remain stable for life. We experimentally manipulated the pair-formation period in aviary pairs prior to their first breeding season and observed the effect of varying pair bond duration on breeding success, male parental effort and breeding coordination. This was done for pairs with long (6.5 months), medium (4 months) and short (2 weeks) formation periods. Our results suggest that the length of the bonding period does not influence male parental effort, as males with medium and short formation periods did not reduce their parental effort in nest building, during incubation or in nestling provisioning. Nevertheless, coordination of pair partners (in terms of simultaneous start of nest building) occurred more often when the pair bond period was long, and these pairs also started breeding earlier. Pairs with long bonds succeeded more often in breeding attempts and had higher hatching and fledging success than pairs with medium and short formation periods. Thus, our results support the hypothesis that the duration of the pair bond may improve coordination within a pair before the start of breeding and thereby may result in enhanced reproductive success.► We examined the role of the extended pair-bond period in the bearded reedling. ► We manipulated the pair-formation period in aviary pairs prior to their first breeding season. ► The length of the bonding period does not influence male parental effort. ► Pairs with long bonds succeeded more often in breeding attempts.
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Colourful feathers are important traits in female mate choice in birds because the colour properties of the feathers are often correlated with individual condition during moult. Feather colour can change after moult, and dirt accumulation... more
Colourful feathers are important traits in female mate choice in birds because the colour properties of the feathers are often correlated with individual condition during moult. Feather colour can change after moult, and dirt accumulation has been suggested to contribute to this variation. However, we still know little about the influence of dirt on feather colour change, possibly because it is difficult to experimentally manipulate the level of feather dirtiness. We investigated whether reflectance properties of feathers exposed to naturally deposited soil (atmospheric particle deposition such as dust, pollution and smoke) differ from feathers for which this contact was prevented. To achieve this, we compared the spectral colour of throat-breast feathers of European starling, Sturnus vulgaris, kept in the open air (dirty group) with those preserved within a plastic envelope (clean group). Before treatment and three and six weeks after the beginning of the treatment we measured the plumage reflectance of the two groups of feathers. While clean feathers did not change their reflectance spectra, the dirty group showed a reduced reflectance along the entire spectrum (300–700 nm). The reduction in reflectance was particularly pronounced in the UV range (300–400 nm). These preliminary results are consistent with the idea that feather colours are not static signals but are plastic traits. However, much work remains to determine the role of soil and air pollution in altering plumage colouration.
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Several factors can influence the risk of cuckoldry through extra-pair paternity for male birds. The number of neighbouring males is thought to affect the chance of females engaging in extra-pair copulations, and species which breed both... more
Several factors can influence the risk of cuckoldry through extra-pair paternity for male birds. The number of neighbouring males is thought to affect the chance of females engaging in extra-pair copulations, and species which breed both socially (colonially) and solitarily provide an ideal opportunity to test the effect of close proximity on extra-pair behaviour and paternity guards. In this study, the extent to which male house sparrows, Passer domesticus, used two alternative strategies, namely frequent copulation and mate-guarding, to ensure paternity was investigated. We also examined how males vary the two paternity guards according to their breeding sociality. Pairs at the dense colony started to copulate at a higher rate at the beginning of the fertile period than those of the medium-sized colony and solitary breeding pairs. Male house sparrows appear to fine-tune their strategies according to the breeding density. Both strategies are alternatively used in the weak fertile period but are simultaneously used in the peak fertile period. Our results suggest that males modify their strategy according to their individual abilities: mate-guarding intensity was positively correlated with the black breast badge size.
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There is growing evidence that moult speed affects plumage quality. In many bird species, males and females differ in terms of breeding effort, survival expectation and the relationship between fitness and plumage quality. Consequently,... more
There is growing evidence that moult speed affects plumage quality. In many bird species, males and females differ in terms of breeding effort, survival expectation and the relationship between fitness and plumage quality. Consequently, differences in moult strategies between the sexes can be expected. The aim of this study was to assess whether, under simulated time constraints and with no parental investment in the previous breeding season, males and females differed in: a) timing and duration of primary moult, b) growth rates of individual primary feathers, and c) number of concurrently growing feathers. We investigated the effect of time constraints generated by a treatment consisting of two decreasing photoperiods (slow changing photoperiod, SCP=2 min day−1 and fast changing photoperiod, FCP=8 min day−1) on the primary post-nuptial moult of captive rock sparrows Petronia petronia. Females started to moult on average 14 and 15 days later than males in both experimental groups. Primary moult duration was 10 (FCP) and 24 (SCP) days longer in males than in females, and, within sex, 34 (females) and 48 (males) days longer in SCP birds than in FCP ones. Females renewed a larger number of primaries simultaneously (5.7% in FCP and 12.8% in SCP) and had a higher total daily feather mass grown (9.9% in FCP and 22.4% in SCP), even though daily growth rates of individual primaries did not differ between sexes. As a result, males and females completed their primary moult at the same time within treatment. The observed differences in timing, duration and energy allocation for primary moult between the sexes probably have a genetic basis, as birds did not engage in reproduction during the preceding breeding season.
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We investigated the effects of resource distribution on the population structure and distribution of a polytypic bird species. We compared the presence of insect remains (mainly dormant larvae) in the winter diet of two reed bunting... more
We investigated the effects of resource distribution on the population structure and distribution of a polytypic bird species. We compared the presence of insect remains (mainly dormant larvae) in the winter diet of two reed bunting subspecies, small billed E. s. schoeniclus and large billed E. s. intermedia and studied the distribution of this resource within reed (Phragmites sp.) stems in seven north Italian localities where the two subspecies breed (three schoeniclus and four intermedia populations). We also tested if the distributions of winter insect resources and breeding populations of the large bill subspecies overlapped. The distribution of the larvae in reed stems matched closely the distribution of large billed breeding populations. The winter diets of the two subspecies were significantly different in terms of frequency of insect remains. These results, when compared to theoretical models of para-patric distribution, suggest that the two subspecies may be subject to ecological (vicariant) selection maintaining their reproductive isolation. © 2002 The Linnean Society of London, Biological Journal of the Linnean Society, 2002, 75, 21–26.
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The incidence of extra‐pair paternity and egg dumping was investigated in a colony of common terns (Sterna hirundo), a colonial seabird, in the Venetian lagoon. Ten families were sampled and multilocus DNA fingerprinting analysis was... more
The incidence of extra‐pair paternity and egg dumping was investigated in a colony of common terns (Sterna hirundo), a colonial seabird, in the Venetian lagoon. Ten families were sampled and multilocus DNA fingerprinting analysis was performed. No indication of extra‐pair paternity or egg dumping was found in any of the families. The results are discussed in the light of life‐history strategies, the benefits of coloniality and the evolution of adoption behaviour in the species.
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In some birds, feather ornaments are expressed in nestlings well before sexual maturation, possibly in response to parental favouritism towards high-quality offspring. In species with synchronous hatching, in which nestling ornaments may... more
In some birds, feather ornaments are expressed in nestlings well before sexual maturation, possibly in response to parental favouritism towards high-quality offspring. In species with synchronous hatching, in which nestling ornaments may vary more among than within broods, parents may use this information to adjust their parental allocation to the current brood accordingly. We tested this hypothesis in the rock sparrow, in which a sexually selected yellow feather ornament is also expressed in nestlings. We experimentally enlarged nestlings’ breast patch in a group of broods and sham-manipulated another group of control broods. Nestlings with enlarged ornament were fed more frequently and defended more actively from a dummy predator than their control counterparts. Mothers from the enlarged group were more likely to lay a second clutch and showed a reduced survival to the next breeding season. These results provide one of the first evidences of differential parental allocation among different broods based directly on nestlings’ ornamentation, and the first, to our knowledge, to show a reduction in maternal survival.
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Growing evidence suggests that structural feather colours honestly reflect individual quality or body condition but, contrary to pigment-based colours, it is not clear what mechanism links condition to reflectance in structural feather... more
Growing evidence suggests that structural feather colours honestly reflect individual quality or body condition but, contrary to pigment-based colours, it is not clear what mechanism links condition to reflectance in structural feather colours. We experimentally accelerated the moult speed of a group of blue tits (Cyanistes caeruleus) by exposing them to a rapidly decreasing photoperiod and compared the spectral characteristics of their structural feather colours with those of control birds. Blue tits were sexually dimorphic on the UV/blue crown and on the white cheek feathers. Moult speed, however, dramatically reduced brightness and the saturation only on the UV/blue crown feathers, whereas structural white on the cheek feathers was basically unaffected by moult speed. Given that the time available for moulting is usually confined to the period between the end of the breeding season and migration or wintering, UV/blue colours, but not structural white, may convey long-term information about an individual’s performance during the previous breeding season. The trade-off between fast moulting and structural colour expression may represent a previously unrecognized selective advantage for early-breeding birds.
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An individual's investment in mating or keeping a pair bond intact may be influenced not only by the attractiveness of its current mate, but also by that of other potential mates. In this study, we investigated the effect of relative... more
An individual's investment in mating or keeping a pair bond intact may be influenced not only by the attractiveness of its current mate, but also by that of other potential mates. In this study, we investigated the effect of relative attractiveness on pair-bond behaviour in bearded reedlings, Panurus biarmicus. We showed that mate attractiveness, in terms of beard length in males and tail length in females, influenced courtship behaviour when the pair was kept isolated. In the presence of a conspecific, contact initiations within a pair increased.
Background Female condition-dependent variation in mate preference may have important evolutionary implications, not only within the same population but also among populations. There are few experiments, however, on how condition and/or... more
Background Female condition-dependent variation in mate preference may have important evolutionary implications, not only within the same population but also among populations. There are few experiments, however, on how condition and/or genotype influences female mate preferences. The black throat patch of the male house sparrow, Passer domesticus, is an intensively studied plumage trait. It is often referred to as a'badge of status' and seems to be involved in female mate choice, but differences exist among populations.
Social network theory provides a perfect tool to better understand the population-level consequences of how individuals interact and make their decisions; however, this approach is generally overlooked among evolutionary biologists... more
Social network theory provides a perfect tool to better understand the population-level consequences of how individuals interact and make their decisions; however, this approach is generally overlooked among evolutionary biologists interested in social relationships. Here, we used social network analysis to examine the patterns of leader-follower interactions in relation to individual characteristics in foraging groups of free-living rock sparrows (Petronia petronia).
Abstract Growing evidence suggests that structural feather colours honestly reflect individual quality or body condition but, contrary to pigment-based colours, it is not clear what mechanism links condition to reflectance in structural... more
Abstract Growing evidence suggests that structural feather colours honestly reflect individual quality or body condition but, contrary to pigment-based colours, it is not clear what mechanism links condition to reflectance in structural feather colours. We experimentally accelerated the moult speed of a group of blue tits (Cyanistes caeruleus) by exposing them to a rapidly decreasing photoperiod and compared the spectral characteristics of their structural feather colours with those of control birds.
There is growing evidence that moult speed affects plumage quality. In many bird species, males and females differ in terms of breeding effort, survival expectation and the relationship between fitness and plumage quality. Consequently,... more
There is growing evidence that moult speed affects plumage quality. In many bird species, males and females differ in terms of breeding effort, survival expectation and the relationship between fitness and plumage quality. Consequently, differences in moult strategies between the sexes can be expected.
Electing to invest in parental care is an adaptive decision thought to involve a trade-off between remating and continuing parental effort. The rock sparrow, Petronia petronia, is an unusual species in which parental investment is highly... more
Electing to invest in parental care is an adaptive decision thought to involve a trade-off between remating and continuing parental effort. The rock sparrow, Petronia petronia, is an unusual species in which parental investment is highly variable and both sexes may desert the brood. Males contemporaneously engage in parental care, mate guarding, and courting their current or new females.