The Experts below are selected from a list of 2331 Experts worldwide ranked by ideXlab platform
Jerzy Banbura - One of the best experts on this subject based on the ideXlab platform.
-
consequences of experimental addition of fresh aromatic plants into nests of blue tits Cyanistes Caeruleus on the physiological condition of nestlings
Behavioral Ecology and Sociobiology, 2020Co-Authors: Michal Glądalski, Adam Kalinski, Jaroslaw Wawrzyniak, Miroslawa Banbura, Joanna Skwarska, Piotr Zielinski, Marcin Markowski, Jerzy BanburaAbstract:The blue tit (Cyanistes Caeruleus) is one of a few known passerine birds that incorporate fresh fragments of aromatic plants in their nest during the nesting period. In this study, we experimentally tested whether aromatic plants in blue tit nests affect physiological condition of nestlings as indicated by hemoglobin and glucose in the blood. Nestlings in nests supplemented with fresh, aromatic plants had elevated blood hemoglobin, and therefore improved physiological condition, as compared with control nestlings. There was no difference between nestlings in two contrasting habitats (urban parkland and forest). Although mean levels of blood glucose did not differ between treatment and control nestlings, the blood of forest nestlings contained more glucose than the blood of parkland nestlings, which indicates poorer health for forest nestlings. In general, knowledge of the effects of incorporating fresh green, aromatic plant material into avian nests on physiological condition of nestlings is still fragmentary and more experimental studies are needed. The blue tit is one of a few known passerine birds that incorporate fresh fragments of aromatic plants in their nest during the nesting period. Little is known about the impact of this material on nestling body condition, and there is a need to understand this behavior and its effects. We tested whether nestlings in nests supplemented with fresh, aromatic plants improved their physiological condition in comparison with control nestlings. The experiment showed that nestlings from supplemented nests improved their physiological condition by exhibiting elevated hemoglobin.
-
a consistent long lasting pattern of spatial variation in egg size and shape in blue tits Cyanistes Caeruleus
Frontiers in Zoology, 2018Co-Authors: Miroslawa Banbura, Adam Kalinski, Jaroslaw Wawrzyniak, Joanna Skwarska, Piotr Zielinski, Michal Glądalski, Marcin Markowski, Jerzy BanburaAbstract:Interspecies variation in avian egg shape and size is understandable in terms of adaptation, allometry and phylogeny. Within-species variation in egg properties influences offspring fitness and can be explained by differences in allocation of resources into reproductive components of life history in mulidimensionally variable environments. Egg size is inherently traded-off with clutch size, which may also be true of egg shape in some cases. We investigated long-term variation in egg shape and size between two geographically close populations of blue tits Cyanistes Caeruleus in relation to clutch size and habitat differences. The main finding is that there exists a persistent long-lasting pattern of spatial variation of egg size and shape between the two study populations of blue tits, 10 km apart, controlling for clutch size. Eggs in the urban park site were on average larger in volume and less spherical in shape than eggs in the forest site over 12 years of this study. Egg sizes were negatively associated with clutch sizes. Egg shape was not correlated with clutch size. Our findings suggest that the pattern of variation in egg size and shape results from different trophic richness of the breeding habitats of the study populations, demanding different allocation of resources and, especially, from the contrasting difference in the availability of calcium.
-
relationships between nestling hemoglobin concentration and brood performance until fledging in great tits parus major and blue tits Cyanistes Caeruleus
Acta Ornithologica, 2017Co-Authors: Adam Kalinski, Jaroslaw Wawrzyniak, Miroslawa Banbura, Joanna Skwarska, Piotr Zielinski, Michal Glądalski, Marcin Markowski, Jerzy BanburaAbstract:Abstract. Partial mortality in broods of altricial passerines results from various reasons, including deficiency of resources, inadequate parental care, diseases and other external factors. In this study we test two hypotheses concerning the phenomenon of partial mortality in nestling altricial passerines: (1) non-adaptive starvation hypothesis based on the assumption that partial brood losses are caused by starvation and undernourishment and has no adaptive value, and (2) adaptive starvation hypothesis assuming that losses from starvation might be elements of an adaptive strategy of reducing surplus nestlings in broods that are over-large. To test the above hypotheses we divided broods of two tit species Great Tit Parus major and Blue Tit Cyanistes Caeruleus into two categories: broods with incomplete, less than 100% fledging success and broods with complete 100% fledging success. Subsequently, we compared physiological performance of nestlings between brood categories using blood hemoglobin concentratio...
-
spatial variation in haemoglobin concentration of nestling blue tits Cyanistes Caeruleus a long term perspective
Journal of Ornithology, 2016Co-Authors: Michal Glądalski, Adam Kalinski, Jaroslaw Wawrzyniak, Miroslawa Banbura, Joanna Skwarska, Piotr Zielinski, Marcin Markowski, Jerzy BanburaAbstract:An understanding of the influences of anthropogenic disturbance and variation in habitat quality on organism condition and breeding success may improve future management and conservation decisions. Some authors consider haemoglobin concentration to be a simple biochemical indicator of bird condition. The main goal of this paper is to examine if the level of haemoglobin displays any consistent pattern of variation across habitats differing in quality. We present results concerning long-term variation in haemoglobin concentration in the blood of about 14-day-old nestling Blue Tits (Cyanistes Caeruleus) in central Poland in an 11-year period (2003–2013), in two landscapes (an urban parkland and a deciduous forest). The most important findings of the study are: (1) the concentration of haemoglobin of the nestlings from the same brood tended to be consistently similar, with most variation occurring between broods, (2) mean levels of haemoglobin varied between years, and were correlated with caterpillar abundance peaks in the forest study site, (3) mean haemoglobin concentration was significantly higher in the forest area than in the parkland area, (4) haemoglobin levels were positively correlated with breeding and fledging success. We confirmed that haemoglobin concentration displays a spatio-temporal pattern and that the level of haemoglobin is a reliable condition and habitat quality indicator in nestling Blue Tits in the study populations. Although, strictly speaking, the analysed differences are between two particular sites, we think that they reflect differences between urban and non-urban habitats.
-
landscape patterns of variation in blood glucose concentration of nestling blue tits Cyanistes Caeruleus
Landscape Ecology, 2014Co-Authors: Adam Kalinski, Jaroslaw Wawrzyniak, Miroslawa Banbura, Joanna Skwarska, Piotr Zielinski, Michal Glądalski, Marcin Markowski, Iwona Cyzewska, Jerzy BanburaAbstract:Integration of landscape ecology and conservation physiology has been recommended as a potentially useful way to investigate consequences of human-induced changes in habitats for animal populations. A central goal of this paper was to examine if a simple physiological parameter displays any consistent patterns of spatio-temporal variation. Blood glucose concentration in birds reflects their high metabolic demands and may be influenced by a number of environmental factors. Therefore we present results concerning variation in glucose concentration in the blood of c. 14-day-old nestling blue tits (Cyanistes Caeruleus) in central Poland in an 8-year period, 2005–2012, in two landscapes: an urban parkland and a deciduous forest. The most important findings of the study were: (1) mean levels of blood glucose varied markedly among years, most probably due to variable weather conditions, (2) glucose concentrations were significantly higher in the parkland study site than in the forest site, (3) heavier nestlings had lower glucose levels, and (4) high glucose levels were negatively correlated with fledging and breeding success. Thus we have confirmed that a consistent spatio-temporal pattern really exists.
Juan J. Sanz - One of the best experts on this subject based on the ideXlab platform.
-
habitat structure modulates nestling diet composition and fitness of blue tits Cyanistes Caeruleus in the mediterranean region
Bird Study, 2017Co-Authors: Eva Serranodavies, Juan J. SanzAbstract:ABSTRACTCapsule: The nestling diet of Blue Tits Cyanistes Caeruleus is influenced by parental effort and habitat type, and consequently has an impact on breeding success.Aims: In a three-year study, we compared the nestling diet of Blue Tits in two Mediterranean forests (pinewood and oakwood) and tested its implications for breeding success.Methods: Adults were captured at the nest to obtain morphological measurements, and provisioning behaviour was recorded when chicks were 11 days old. Nestling tarsus length and body mass were measured on day 13 after hatching.Results: Caterpillars constituted the largest proportion of nestling diet in both habitats, however, higher numbers and biomass of noctuid, as well as higher numbers of tortricid larvae, were provided to nestlings in the pinewood. Furthermore, females provided tortricids more often than males, whereas males supplied more geometrid larvae and spiders. We found a more generalist diet for nestlings raised in the pinewood. Also, a greater number of yo...
-
incubation behaviour of blue Cyanistes Caeruleus and great tits parus major in a mediterranean habitat
Acta Ornithologica, 2017Co-Authors: Javier Buenoenciso, Rafael Barrientos, Juan J. SanzAbstract:The incubation stage in avian reproduction could be as costly as the nestling rearing stage. This is particularly true in the case of uniparental incubation, during which both current and future breeding attempts may be compromised. Therefore, the knowledge of the proximate effects that condition the incubation behaviour in free-living bird populations is of great importance in understanding the evolution of avian life history. In this two-year study, we assessed the incubation behaviours of Blue Cyanistes Caeruleus and Great Tits Parus major inhabiting the same Mediterranean area in central Spain through the usage of iButton data loggers. It showed that the incubating behaviour of our tit populations resembles that reported in previous studies, but with peculiarities related to living at lower latitudes, i.e. with a relatively low attentiveness and a shorter active day. Both tit species showed very different incubation strategies, with Blue Tits leaving more frequently the nest (Mean ± SE number of off-bouts, Blue Tit = 27.14 ± 0.63, Great Tit = 16.95 ± 0.58) but for shorter periods than Great Tits (off-bout duration, Blue Tit = 8.76 ± 0.22 min, Great Tit = 14.04 ± 0.56 min; on-bout duration, Blue Tit = 22.63 ± 0.60 min, Great Tit = 36.86 ± 0.86 min). Nonetheless, both species provided a similar nest attentiveness, percentage of time of the active day during which the females were actively incubating (Blue Tit = 70.87 ± 0.57%, Great Tit = 70.75 ± 0.83%). Presumably, differences in the cooling rate of clutches, estimated with the iButtons, could be behind the differences in incubation behaviour between species and the greater capacity of Great Tits to adjust their incubation behaviour.
-
individual genetic diversity and probability of infection by avian malaria parasites in blue tits Cyanistes Caeruleus
Journal of Evolutionary Biology, 2014Co-Authors: Juan J. Sanz, Esperanza S. Ferrer, Vicente Garcianavas, Joaquín OrtegoAbstract:Understanding the importance of host genetic diversity for coping with parasites and infectious diseases is a long-standing goal in evolutionary biology. Here, we study the association between probability of infection by avian malaria (Plasmodium relictum) and individual genetic diversity in three blue tit (Cyanistes Caeruleus) populations that strongly differ in prevalence of this parasite. For this purpose, we screened avian malaria infections and genotyped 789 blue tits across 26 microsatellite markers. We used two different arrays of markers: 14 loci classified as neutral and 12 loci classified as putatively functional. We found a significant relationship between probability of infection and host genetic diversity estimated at the subset of neutral markers that was not explained by strong local effects and did not differ among the studied populations. This relationship was not linear, and probability of infection increased up to values of homozygosity by locus (HL) around 0.15, reached a plateau at values of HL from 0.15 to 0.40 and finally declined among a small proportion of highly homozygous individuals (HL > 0.4). We did not find evidence for significant identity disequilibrium, which may have resulted from a low variance of inbreeding in the study populations and/or the small power of our set of markers to detect it. A combination of subtle positive and negative local effects and/or a saturation threshold in the association between probability of infection and host genetic diversity in combination with increased resistance to parasites in highly homozygous individuals may explain the observed negative quadratic relationship. Overall, our study highlights that parasites play an important role in shaping host genetic variation and suggests that the use of large sets of neutral markers may be more appropriate for the study of heterozygosity–fitness correlations.
-
environmental and within nest factors influencing nestling feeding patterns of mediterranean blue tits Cyanistes Caeruleus
The Condor, 2012Co-Authors: Vicente Garcianavas, Juan J. SanzAbstract:Abstract. The rate at which parent birds deliver food to their young may depend on several factors, both intrinsic (e.g., brood demand) and extrinsic (e.g., time of day). Using PIT tags, we determined patterns of nestling provisioning in the Blue Tit (Cyanistes Caeruleus) and the proximate factors affecting them. Over 3 years, we monitored the rates of provisioning by Blue Tits in two types of forest (evergreen and deciduous) in Cabaneros National Park (Spain). Pairs breeding in the deciduous forest visited the nest at rates higher than did those in the evergreen forest. Contrary to expectation, males fed their offspring more than females did, and the rates of feeding were positively related to those of the social partner. Sex roles in provisioning were consistent through the day, suggesting that parents did not work in concert. Provisioning rates also tended to decline through the day and were negatively correlated with ambient temperature. In females, but not in males, the adult's body condition was neg...
-
Molecular characterization of avian malaria parasites in three Mediterranean blue tit (Cyanistes Caeruleus) populations
Parasitology Research, 2012Co-Authors: Esperanza S. Ferrer, Juan J. Sanz, Vicente García-navas, Joaquín OrtegoAbstract:We genetically analysed malaria parasites (Protozoa) in three Mediterranean blue tit (Cyanistes Caeruleus) popula- tions from central Spain. A total of 853 breeding individuals were screened for parasites of the genera Plasmodium and Haemoproteus using a very efficient polymerase chain reaction approach that amplifies a partial segment of the mitochondrial cytochrome b gene of these parasites. We have found six line- ages of Plasmodium (SGS1, GRW11, COLL1, DELURB4, GRW04 and BLUTI10) parasitizing the studied populations but we did not detect any infection byHaemoproteus. One of the detected lineages (BLUTI10) has not been previously de- scribed in any bird species and this is the first study recording lineages DELURB4 and GRW04 in blue tits. SGS1 (belonging to the morphospecies Plasmodium relictum) was the most fre- quent lineage (overall prevalence, 24 %), whereas the other lineages showed a much lower prevalence (
M Cichoń - One of the best experts on this subject based on the ideXlab platform.
-
sex specific heritability of cell mediated immune response in the blue tit nestlings Cyanistes Caeruleus
Journal of Evolutionary Biology, 2010Co-Authors: Szymon M Drobniak, D Wiejaczka, Aneta Arct, Anna Dubiec, Lars Gustafsson, M CichońAbstract:Here, we aimed at estimating sex-specific heritabilities of cell-mediated immune response (CMI) in the blue tit nestlings (Cyanistes Caeruleus). To separate genetic and environmental components of the phenotypic variance in CMI (measured using phytohaemagglutinin assay), we performed a cross-fostering experiment. Additionally, controlled environmental variation was introduced by enlarging some broods. Our analyses revealed a significant genetic component (as approximated by the nest-of-origin term) of the phenotypic variance in immune response. More importantly, these genetic effects differed between sexes and experimentally manipulated brood sizes, as indicated by significant genotype-by-sex and genotype-by-environment interactions. We discuss possible causes of such sexual dimorphism in gene expression and suggest that sex- and environment-specific genetic interactions may contribute to the maintenance of genetic variability in traits related to immune functions.
-
Sex‐specific heritability of cell‐mediated immune response in the blue tit nestlings (Cyanistes Caeruleus)
Journal of Evolutionary Biology, 2010Co-Authors: Szymon M Drobniak, D Wiejaczka, Aneta Arct, Anna Dubiec, Lars Gustafsson, M CichońAbstract:Here, we aimed at estimating sex-specific heritabilities of cell-mediated immune response (CMI) in the blue tit nestlings (Cyanistes Caeruleus). To separate genetic and environmental components of the phenotypic variance in CMI (measured using phytohaemagglutinin assay), we performed a cross-fostering experiment. Additionally, controlled environmental variation was introduced by enlarging some broods. Our analyses revealed a significant genetic component (as approximated by the nest-of-origin term) of the phenotypic variance in immune response. More importantly, these genetic effects differed between sexes and experimentally manipulated brood sizes, as indicated by significant genotype-by-sex and genotype-by-environment interactions. We discuss possible causes of such sexual dimorphism in gene expression and suggest that sex- and environment-specific genetic interactions may contribute to the maintenance of genetic variability in traits related to immune functions.
Szymon M Drobniak - One of the best experts on this subject based on the ideXlab platform.
-
maternal age related depletion of offspring genetic variance in immune response to phytohaemagglutinin in the blue tit Cyanistes Caeruleus
Evolutionary Biology-new York, 2015Co-Authors: Szymon M Drobniak, Anna Dubiec, Lars Gustafsson, Mariusz CichonAbstract:Studies examining age-specific patterns in genetic variance have focussed primarily on changes in the genetic variance within cohorts. It remains unclear whether parental age may affect the genetic variance among offspring. To date, such an effect has been reported only in a single study performed in a wild bird population. Here, we provide experimental evidence that the additive genetic variance (VA) observed among offspring may be related to parental age in a wild passerine—the blue tit (Cyanistes Caeruleus). To separate genetic and environmental components of phenotypic variance in nestling body size and immune function we cross-fostered nestlings between pairs of broods born to young and old mothers and used an animal model to estimate VA. We show that the genetic variance in immune response to phytohaemagglutinin (PHA) and body weight among offspring depends on maternal age. VA in response to PHA appeared to be lower among nestlings of older mothers. Such a tendency was not observed for tarsus length. We argue that the lower VA may result either from depletion of additive genetic variation due to selection acting on parents across age classes or from environmental effects confounded with parental age. Thus, our study suggests that parental age may significantly affect estimates of quantitative genetic parameters in the offspring.
-
experimentally increased reproductive effort alters telomere length in the blue tit Cyanistes Caeruleus
Journal of Evolutionary Biology, 2014Co-Authors: Joanna Sudyka, Szymon M Drobniak, Aneta Arct, Anna Dubiec, Lars Gustafsson, Mariusz CichonAbstract:Telomeres have recently been suggested to play important role in ageing and are considered to be a reliable ageing biomarkers. The life history theory predicts that costs of reproduction should be expressed in terms of accelerated senescence, and some empirical studies do confirm such presumption. Thus, a link between reproductive effort and telomere dynamics should be anticipated. Recent studies have indeed demonstrated that reproduction may trigger telomere loss, but actual impact of reproductive effort has not received adequate attention in experimental studies. Here, we experimentally manipulated reproductive effort by increasing the brood size in the wild blue tit (Cyanistes Caeruleus). We show that parents attending enlarged broods experienced larger yearly telomere decay in comparison to control birds attending unaltered broods. In addition, we demonstrate that the change in telomere length differs between sexes, but this effect was independent from our treatment. To our knowledge, this is the first experimental study in the wild revealing that telomere dynamics may be linked to reproductive effort. Thus, telomere shortening may constitute one of the potential proximate mechanisms mediating the costs of reproduction.
-
sex specific heritability of cell mediated immune response in the blue tit nestlings Cyanistes Caeruleus
Journal of Evolutionary Biology, 2010Co-Authors: Szymon M Drobniak, D Wiejaczka, Aneta Arct, Anna Dubiec, Lars Gustafsson, M CichońAbstract:Here, we aimed at estimating sex-specific heritabilities of cell-mediated immune response (CMI) in the blue tit nestlings (Cyanistes Caeruleus). To separate genetic and environmental components of the phenotypic variance in CMI (measured using phytohaemagglutinin assay), we performed a cross-fostering experiment. Additionally, controlled environmental variation was introduced by enlarging some broods. Our analyses revealed a significant genetic component (as approximated by the nest-of-origin term) of the phenotypic variance in immune response. More importantly, these genetic effects differed between sexes and experimentally manipulated brood sizes, as indicated by significant genotype-by-sex and genotype-by-environment interactions. We discuss possible causes of such sexual dimorphism in gene expression and suggest that sex- and environment-specific genetic interactions may contribute to the maintenance of genetic variability in traits related to immune functions.
-
Sex‐specific heritability of cell‐mediated immune response in the blue tit nestlings (Cyanistes Caeruleus)
Journal of Evolutionary Biology, 2010Co-Authors: Szymon M Drobniak, D Wiejaczka, Aneta Arct, Anna Dubiec, Lars Gustafsson, M CichońAbstract:Here, we aimed at estimating sex-specific heritabilities of cell-mediated immune response (CMI) in the blue tit nestlings (Cyanistes Caeruleus). To separate genetic and environmental components of the phenotypic variance in CMI (measured using phytohaemagglutinin assay), we performed a cross-fostering experiment. Additionally, controlled environmental variation was introduced by enlarging some broods. Our analyses revealed a significant genetic component (as approximated by the nest-of-origin term) of the phenotypic variance in immune response. More importantly, these genetic effects differed between sexes and experimentally manipulated brood sizes, as indicated by significant genotype-by-sex and genotype-by-environment interactions. We discuss possible causes of such sexual dimorphism in gene expression and suggest that sex- and environment-specific genetic interactions may contribute to the maintenance of genetic variability in traits related to immune functions.
Jan Komdeur - One of the best experts on this subject based on the ideXlab platform.
-
Is UV signalling involved in male-male territorial conflict in the blue tit (Cyanistes Caeruleus)? A new experimental approach
Behaviour, 2020Co-Authors: Peter Korsten, Thomas H Dijkstra, Jan KomdeurAbstract:Structurally-based ultraviolet (UV) coloration of plumage can signal male quality and plays a role in female mate choice in many bird species. UV-reflecting badges could also be important signals in male-male competition. We tested if territorial blue tit (Cyanistes Caeruleus) males discriminate between conspecific male intruders which differ in the UV reflectance of their crown feathers. To this aim, we used a new experimental approach in which we simultaneously (instead of sequentially) introduced two male blue tit taxidermic mounts in the territories of resident males during the female fertile period; one mount with natural crown UV reflectance and one mount with reduced crown UV. The two mounts provoked strong aggressive reactions from resident males. Males specifically directed their aggression to conspecific intruders, as a male blue tit mount received substantially more aggression than a mount of a European robin (Erithacus rubecula). However, aggression of resident males did not vary between the UV-reduced and the control mount. Furthermore, the variation in natural crown UV reflectance of the resident males did not predict the intensity of their aggressive response. Contrary to previous findings our results suggest that UV signals play only a limited role in male-male interactions during territorial intrusions in the female fertile period.
-
effect of tree logging on reproductive performance in blue tits Cyanistes Caeruleus
Journal of Ornithology, 2017Co-Authors: Seyed Mehdi Amininasab, Charles C Y Xu, Sjouke A Kingma, Jan KomdeurAbstract:For birds, habitat quality is largely determined by local vegetation, and reproductive performance can therefore be negatively influenced by anthropogenic activities. A tree logging event enabled us to examine the effect of removing trees of different maturities and types on the reproductive performance of Blue Tits (Cyanistes Caeruleus). Against expectations, only the logging of small coniferous trees, but not larger and deciduous trees, was associated with a reduction in the number of eggs laid, whereas logging had no significant effect on lay date. Therefore, we conclude that modest logging activity has no or limited negative influence on Blue Tit reproductive performance.
-
testosterone reduces promiscuity of female blue tits Cyanistes Caeruleus an experimental study
Ethology, 2017Co-Authors: Berber De Jong, Peter Korsten, Ton G G Groothuis, Luc Lens, Marco Van Der Velde, Jan KomdeurAbstract:In many animal species, extra-pair copulations (EPCs) are common and can increase fitness in both sexes. In males, EPCs can increase total reproductive output, whereas in females benefits of EPCs can be indirect through improving the genetic quality of their offspring. Males and females of many vertebrates show an increase in levels of the hormone testosterone (T) during the mating period. In males, T plays an important role in regulating mating behaviour including increasing their EPC rate. While much is known about the role of T in male mating behaviour, the role of T in female reproduction remains unclear. To study the influence of T on extra-pair paternity rates in females in a field setting, we created three experimental groups of female blue tits (Cyanistes Caeruleus): treated with either T, flutamide (Flu; an androgen receptor blocker) or empty implants before egg laying. Subsequently, we scored the number of extra-pair offspring (EPO) in their broods. We also assessed the attractiveness of females treated with either T or Flu to males in mate choice trials in the laboratory. The overall proportion of EPO was lower for the T-implanted group compared with the control group, whereas Flu had no effect. Given that males did not show a preference for Flu- vs. T-treated females in the mate choice trials, it appears less likely that the reduction in EPO in the T-implanted females was due to a reduction in their attractiveness. T levels may have negatively influenced EPO rate by affecting female within-pair and/or extra-pair mating behaviour. Future behavioural studies should investigate how elevated T levels reduce the number of EPO.
-
sperm depletion does not account for undeveloped eggs in blue tits Cyanistes Caeruleus
Ibis, 2014Co-Authors: Elske Schut, Jan Komdeur, Oscar Vedder, Michael J. L. MagrathAbstract:Hatching failure negatively impacts reproductive success in birds. One reason why eggs fail to hatch is that they are not fertilized, which may be because they receive insufficient sperm. In most passerines, copulation declines in frequency or ceases altogether after the laying of the first egg, so eggs laid late in the laying sequence may be more likely to remain unfertilized. We tested this prediction in the Blue Tit Cyanistes Caeruleus, a species in which late-laid eggs are particularly likely to be sperm-limited because it lays the largest clutch of any passerine. We assessed whether: (1) eggs laid later in the laying sequence are more likely to fail to develop, (2) larger clutches are more likely to contain undeveloped eggs, (3) the number of sperm present on the perivitelline layers of each egg decreases across the laying sequence and (4) the number of sperm present on the perivitelline layers of freshly laid eggs sampled from active clutches predicts the proportion of eggs that develop in the remainder of the clutch. The occurrence of undeveloped eggs was not related to their position in the laying sequence, nor was it related to clutch size. Within a clutch, sperm number did not differ between an egg laid early and an egg laid towards the end of the laying sequence. Moreover, there was no indication that the proportion of undeveloped eggs in a clutch correlated with the number of sperm in a subset of eggs from that clutch, or that females laying larger clutches had stored more sperm. In summary, we found no evidence that Blue Tit eggs fail to hatch because they receive insufficient sperm.
-
Volume of the cloacal protuberance as an indication of reproductive state in male Blue Tits Cyanistes Caeruleus
Ardea, 2012Co-Authors: Elske Schut, Michael J. L. Magrath, Kees Van Oers, Jan KomdeurAbstract:In male passerines, the accumulation of sperm in the sperm reserves causes the cloaca to become enlarged, forming the cloacal protuberance (CP). In Blue Tits, the timing of breeding differs considerably between pairs. Hence, when catching a male during the breeding season it may be unclear whether he is in a reproductively active state (i.e. producing sperm). Here, we show in captive Blue Tits Cyanistes Caeruleus that CP volume is increased in males in a reproductively active state when compared to the same males in a reproductively inactive state. However, there was some overlap in CP volume when comparing the values in reproductively active and non-active states. Measurements of CP volume at a single time point, therefore, do not allow the researcher to reliably determine an individual's reproductive status.
