No description available.

Parents modulate the phenotypes of their offspring, beyond the effects of the genes they pass on. These parental effects can have impacts on the fitnesses of those offspring, as well as the fitness of the parents themselves. Parental investment in offspring is expected to be under antagonistic selection through its beneficial effects to offspring, and its detrimental effects on the parent's own fitness. Evolutionary conflict over parental care is therefore expected to occur, and may cause evolutionary stasis. Furthermore, selection is also expected to act on offspring traits, in order to maximise offspring fitness within a given parental environment, generating predictions of parent-offspring coadaptation. I tested the predictions of conflict and coadaptation in parent-offspring interactions, using a population of blue tits (Cyanistes caeruleus), a species in which adults provide biparental care to their offspring. I found evolutionary conflict over offspring body mass, which may explain stasis in this trait. I also used a cross-fostering design to test for coadaptation between parents and offspring, and siblings. I did not find evidence for parent-offspring coadaptation, nor did I find that siblings were important through either direct interactions, or in mediating parent-offspring interactions, suggesting that there is little family coadaptation in this species. In addition, I investigated whether a maternal effect on hatching time was a passive consequence of environmental changes, or was an anticipatory maternal effect actively placed in eggs to manipulate hatching time. The results from this analysis suggest the latter to be the case, and mothers appear to actively manipulate offspring hatching time to reduce the extent of hatching asynchrony, which may reduce fitness costs to the offspring. By measuring the effects of interactions between individuals on phenotypes and fitness measures, I was able to show how parental effects on offspring can affect evolutionary dynamics. Such evidence of evolutionary conflicts has not previously been found, due to methodological issues with the ways in which selection has been measured. Thus, I highlight how gaps in knowledge about the evolutionary consequences of parental effects can be addressed using appropriate statistical tools and measures of fitness.

<p>Förekomsten av migration är vida känt i djurvärlden och fåglars flyttning är kanske den mest uppenbara typen. I vissa populationer flyttar alla fåglar, i andra flyttar ingen. Blåmesen tillämpar partiell migration, dvs. en del individer i populationen flyttar medan andra stannar. Vissa år lämnar partiellt flyttande fåglar fortplantningsområdet i stora antal och invaderar andra områden – dålig födotillgång och höga populationstätheter är två viktiga, utlösande faktorer.</p><p>I den här studien undersöktes successionen av flyttande blåmesar vid Hammarö fågelstation i norra delen av Vänern (HBO) med avseende på ålders- och könsfördelning. Under höstarna 1977-2005 fångades och ringmärktes totalt 13 944 blåmesar vid HBO. Den största delen av de fångade blåmesarna var ungfåglar, av vilka honor och obestämda fåglar dominerade. Juvenila hanar utgjorde den tredje största gruppen, medan de adulta fåglarna var få. Den period då de flesta fåglarna fångades var 28 september till 2 oktober. Mediandatum för fångst var 2 oktober, medan medeldatumet var 30 september. Tvärtemot förutsägelserna anlände inte juvenila honor signifikant tidigare än andra kategorier. Det finns en trend att fåglarna fångas allt tidigare på hösten, vilket kan vara ett resultat av ett varmare vårklimat med tidigarelagd häckning som följd. Regressioner visade att proportionen juvenila fåglar ökade signifikant med medelankomstdatum och med det totala antalet fångade fåglar. En jämförelse mellan HBO, Falsterbo och Ottenby visade att fåglarna anlände signifikant tidigare till HBO. 1990 och 2003 var de enda år då HBO, Falsterbo, Ottenby och Jomfruland fångade fler fåglar än respektive stations medelvärde. Åren 1995, 1998 och 2002 fångades färre fåglar än medelvärdet på samtliga stationer.</p> / <p>Animal migration is a well known natural phenomenon and bird migration is perhaps the most obvious type. In some bird populations all individuals migrate, while in others only a fraction of the population migrates. The blue tit is a partial migrant; i.e. some individuals in the population migrate while others are sedentary. Some years, large numbers of partial migrants leave their breeding grounds and appear as invasion species in other areas. Shortage of food and high population densities are suggested as two important releasing factors. Theory predicts that juvenile birds, especially females, should arrive earlier since they are smaller and therefore are forced to leave their birth areas first.</p><p>In this study, the migration of blue tits at Hammarö Bird Observatory in northern lake Vänern (HBO) was examined with respect to age and sex distribution. During the autumns of 1977-2005, a total number of 13 944 blue tits were caught and ringed at HBO. A large fraction of the caught blue tits were juveniles, of which female and non-sexed birds dominated. Juvenile males were the third largest group, whereas adults were only caught in small numbers. The period when most birds arrived was between 28th of September and 2nd of October, but juvenile females did not arrived significantly earlier. The median arrival date was the 2nd of October, and the mean arrival date was 30th of September. There was a trend of earlier arrival dates, which may be due to warmer spring climate leading to an earlier breeding start. Analyses showed that the proportion of juveniles increased significantly with mean arrival date and total number of birds caught. Comparison between HBO, Falsterbo and Ottenby showed that birds arrived significantly earlier at HBO. In 1990 and 2003 all bird observatories (HBO, Falsterbo, Ottenby and Jomfruland) captured more birds than respectively stations average and in 1995, 1998 and 2002 fewer birds than average were captured at all sites.</p>

<p>Animal migration is a well known natural phenomenon and bird migration is perhaps the most obvious type. In some bird populations all individuals migrate, while in others only a fraction of the population migrates. The blue tit is a partial migrant; i.e. some individuals in the population migrate while others are sedentary. Some years, large numbers of partial migrants leave their breeding grounds and appear as invasion species in other areas. Shortage of food and high population densities are suggested as two important releasing factors. Theory predicts that juvenile birds, especially females, should arrive earlier since they are smaller and therefore are forced to leave their birth areas first.</p><p>In this study, the migration of blue tits at Hammarö Bird Observatory in northern lake Vänern (HBO) was examined with respect to age and sex distribution. During the autumns of 1977-2005, a total number of 13 944 blue tits were caught and ringed at HBO. A large fraction of the caught blue tits were juveniles, of which female and non-sexed birds dominated. Juvenile males were the third largest group, whereas adults were only caught in small numbers. The period when most birds arrived was between 28th of September and 2nd of October, but juvenile females did not arrived significantly earlier. The median arrival date was the 2nd of October, and the mean arrival date was 30th of September. There was a trend of earlier arrival dates, which may be due to warmer spring climate leading to an earlier breeding start. Analyses showed that the proportion of juveniles increased significantly with mean arrival date and total number of birds caught. Comparison between HBO, Falsterbo and Ottenby showed that birds arrived significantly earlier at HBO. In 1990 and 2003 all bird observatories (HBO, Falsterbo, Ottenby and Jomfruland) captured more birds than respectively stations average and in 1995, 1998 and 2002 fewer birds than average were captured at all sites.</p> / <p>Förekomsten av migration är vida känt i djurvärlden och fåglars flyttning är kanske den mest uppenbara typen. I vissa populationer flyttar alla fåglar, i andra flyttar ingen. Blåmesen tillämpar partiell migration, dvs. en del individer i populationen flyttar medan andra stannar. Vissa år lämnar partiellt flyttande fåglar fortplantningsområdet i stora antal och invaderar andra områden – dålig födotillgång och höga populationstätheter är två viktiga, utlösande faktorer.</p><p>I den här studien undersöktes successionen av flyttande blåmesar vid Hammarö fågelstation i norra delen av Vänern (HBO) med avseende på ålders- och könsfördelning. Under höstarna 1977-2005 fångades och ringmärktes totalt 13 944 blåmesar vid HBO. Den största delen av de fångade blåmesarna var ungfåglar, av vilka honor och obestämda fåglar dominerade. Juvenila hanar utgjorde den tredje största gruppen, medan de adulta fåglarna var få. Den period då de flesta fåglarna fångades var 28 september till 2 oktober. Mediandatum för fångst var 2 oktober, medan medeldatumet var 30 september. Tvärtemot förutsägelserna anlände inte juvenila honor signifikant tidigare än andra kategorier. Det finns en trend att fåglarna fångas allt tidigare på hösten, vilket kan vara ett resultat av ett varmare vårklimat med tidigarelagd häckning som följd. Regressioner visade att proportionen juvenila fåglar ökade signifikant med medelankomstdatum och med det totala antalet fångade fåglar. En jämförelse mellan HBO, Falsterbo och Ottenby visade att fåglarna anlände signifikant tidigare till HBO. 1990 och 2003 var de enda år då HBO, Falsterbo, Ottenby och Jomfruland fångade fler fåglar än respektive stations medelvärde. Åren 1995, 1998 och 2002 fångades färre fåglar än medelvärdet på samtliga stationer.</p>

Animal migration is a well known natural phenomenon and bird migration is perhaps the most obvious type. In some bird populations all individuals migrate, while in others only a fraction of the population migrates. The blue tit is a partial migrant; i.e. some individuals in the population migrate while others are sedentary. Some years, large numbers of partial migrants leave their breeding grounds and appear as invasion species in other areas. Shortage of food and high population densities are suggested as two important releasing factors. Theory predicts that juvenile birds, especially females, should arrive earlier since they are smaller and therefore are forced to leave their birth areas first. In this study, the migration of blue tits at Hammarö Bird Observatory in northern lake Vänern (HBO) was examined with respect to age and sex distribution. During the autumns of 1977-2005, a total number of 13 944 blue tits were caught and ringed at HBO. A large fraction of the caught blue tits were juveniles, of which female and non-sexed birds dominated. Juvenile males were the third largest group, whereas adults were only caught in small numbers. The period when most birds arrived was between 28th of September and 2nd of October, but juvenile females did not arrived significantly earlier. The median arrival date was the 2nd of October, and the mean arrival date was 30th of September. There was a trend of earlier arrival dates, which may be due to warmer spring climate leading to an earlier breeding start. Analyses showed that the proportion of juveniles increased significantly with mean arrival date and total number of birds caught. Comparison between HBO, Falsterbo and Ottenby showed that birds arrived significantly earlier at HBO. In 1990 and 2003 all bird observatories (HBO, Falsterbo, Ottenby and Jomfruland) captured more birds than respectively stations average and in 1995, 1998 and 2002 fewer birds than average were captured at all sites. / Förekomsten av migration är vida känt i djurvärlden och fåglars flyttning är kanske den mest uppenbara typen. I vissa populationer flyttar alla fåglar, i andra flyttar ingen. Blåmesen tillämpar partiell migration, dvs. en del individer i populationen flyttar medan andra stannar. Vissa år lämnar partiellt flyttande fåglar fortplantningsområdet i stora antal och invaderar andra områden – dålig födotillgång och höga populationstätheter är två viktiga, utlösande faktorer. I den här studien undersöktes successionen av flyttande blåmesar vid Hammarö fågelstation i norra delen av Vänern (HBO) med avseende på ålders- och könsfördelning. Under höstarna 1977-2005 fångades och ringmärktes totalt 13 944 blåmesar vid HBO. Den största delen av de fångade blåmesarna var ungfåglar, av vilka honor och obestämda fåglar dominerade. Juvenila hanar utgjorde den tredje största gruppen, medan de adulta fåglarna var få. Den period då de flesta fåglarna fångades var 28 september till 2 oktober. Mediandatum för fångst var 2 oktober, medan medeldatumet var 30 september. Tvärtemot förutsägelserna anlände inte juvenila honor signifikant tidigare än andra kategorier. Det finns en trend att fåglarna fångas allt tidigare på hösten, vilket kan vara ett resultat av ett varmare vårklimat med tidigarelagd häckning som följd. Regressioner visade att proportionen juvenila fåglar ökade signifikant med medelankomstdatum och med det totala antalet fångade fåglar. En jämförelse mellan HBO, Falsterbo och Ottenby visade att fåglarna anlände signifikant tidigare till HBO. 1990 och 2003 var de enda år då HBO, Falsterbo, Ottenby och Jomfruland fångade fler fåglar än respektive stations medelvärde. Åren 1995, 1998 och 2002 fångades färre fåglar än medelvärdet på samtliga stationer.

Förekomsten av migration är vida känt i djurvärlden och fåglars flyttning är kanske den mest uppenbara typen. I vissa populationer flyttar alla fåglar, i andra flyttar ingen. Blåmesen tillämpar partiell migration, dvs. en del individer i populationen flyttar medan andra stannar. Vissa år lämnar partiellt flyttande fåglar fortplantningsområdet i stora antal och invaderar andra områden – dålig födotillgång och höga populationstätheter är två viktiga, utlösande faktorer. I den här studien undersöktes successionen av flyttande blåmesar vid Hammarö fågelstation i norra delen av Vänern (HBO) med avseende på ålders- och könsfördelning. Under höstarna 1977-2005 fångades och ringmärktes totalt 13 944 blåmesar vid HBO. Den största delen av de fångade blåmesarna var ungfåglar, av vilka honor och obestämda fåglar dominerade. Juvenila hanar utgjorde den tredje största gruppen, medan de adulta fåglarna var få. Den period då de flesta fåglarna fångades var 28 september till 2 oktober. Mediandatum för fångst var 2 oktober, medan medeldatumet var 30 september. Tvärtemot förutsägelserna anlände inte juvenila honor signifikant tidigare än andra kategorier. Det finns en trend att fåglarna fångas allt tidigare på hösten, vilket kan vara ett resultat av ett varmare vårklimat med tidigarelagd häckning som följd. Regressioner visade att proportionen juvenila fåglar ökade signifikant med medelankomstdatum och med det totala antalet fångade fåglar. En jämförelse mellan HBO, Falsterbo och Ottenby visade att fåglarna anlände signifikant tidigare till HBO. 1990 och 2003 var de enda år då HBO, Falsterbo, Ottenby och Jomfruland fångade fler fåglar än respektive stations medelvärde. Åren 1995, 1998 och 2002 fångades färre fåglar än medelvärdet på samtliga stationer. / Animal migration is a well known natural phenomenon and bird migration is perhaps the most obvious type. In some bird populations all individuals migrate, while in others only a fraction of the population migrates. The blue tit is a partial migrant; i.e. some individuals in the population migrate while others are sedentary. Some years, large numbers of partial migrants leave their breeding grounds and appear as invasion species in other areas. Shortage of food and high population densities are suggested as two important releasing factors. Theory predicts that juvenile birds, especially females, should arrive earlier since they are smaller and therefore are forced to leave their birth areas first. In this study, the migration of blue tits at Hammarö Bird Observatory in northern lake Vänern (HBO) was examined with respect to age and sex distribution. During the autumns of 1977-2005, a total number of 13 944 blue tits were caught and ringed at HBO. A large fraction of the caught blue tits were juveniles, of which female and non-sexed birds dominated. Juvenile males were the third largest group, whereas adults were only caught in small numbers. The period when most birds arrived was between 28th of September and 2nd of October, but juvenile females did not arrived significantly earlier. The median arrival date was the 2nd of October, and the mean arrival date was 30th of September. There was a trend of earlier arrival dates, which may be due to warmer spring climate leading to an earlier breeding start. Analyses showed that the proportion of juveniles increased significantly with mean arrival date and total number of birds caught. Comparison between HBO, Falsterbo and Ottenby showed that birds arrived significantly earlier at HBO. In 1990 and 2003 all bird observatories (HBO, Falsterbo, Ottenby and Jomfruland) captured more birds than respectively stations average and in 1995, 1998 and 2002 fewer birds than average were captured at all sites.

No description available.

Existing research on the foraging ecology and breeding biology of blue tits (Cyanistes caeruleus) and great tits(Parus major) has mainly concentrated on populations in woodland. However increasing urbanisation means much of the suitable tit habitat is represented by fragmented areas, not large woodlands, and little is known about factors that may affect reproductive success in urban environments. Using General and Generalised Linear Models this study compared reproductive performance in four habitat types with differing levels of habitat modification: the Cambridge University Botanic Garden (CUBG) with an abundance of non-native vegetation and structural fragmentation, two marginal sites with native scrubby vegetation and structural fragmentation and small fragments and large fragments of native woodland. Compositional analysis was used in a study focused on how foraging blue tits used the heterogeneous habitat of the CUBG. Additionally frequency tests were used to compare foraging preferences and foraging behaviours of both species in the CUBG. Productivity was poor in the CUBG compared to all of the other habitats, with great tits appearing to do worse than blue tits, rearing lower quality chicks (significantly lower mean mass than in other habitats). Within the CUBG, positive relationships were found between the abundance of native trees and shrubs and breeding success for both blue tits and great tits. A positive relationship was found between breeding success in blue tits and the abundance of Quercus and Betula. However, habitat and year interactions showed that habitat and reproductive relationships were complicated by annual variation. The two species differed in their foraging preferences in the CUBG; blue tits were observed feeding in native deciduous trees significantly more than in non-native species and had a preference for birch trees over other taxa. Great tits however showed no strong preferences for any of the habitat types. With regards to foraging behaviours, great tits used a wider range of foraging heights and different foraging locations and capture techniques than blue tits. Blue tits were observed‘hanging’ from twigs more frequently, and appeared to be more effective at foraging in the wider variety of plants available in the heterogeneous vegetation of the garden. The data presented in this thesis suggest that blue tits have adopted a better foraging strategy by preferentially choosing native deciduous trees over the abundance of non-natives available in the CUBG. However, despite the apparent better foraging strategy of blue tits, reproductive performance of both species is poor in this urban garden compared to marginal sites and woodland. Urbanisation and the associated loss of optimal tit habitat are likely to continue. It is therefore important to offset urbanisation by the addition of appropriate foraging habitats that are likely to improve reproductive success, such as native trees and shrubs.

The drivers of fidelity and divorce of pair-bonded individuals, along with their fitness consequences, are of great interest as they influence mating systems, population structure and productivity, and gene flow. Socially monogamous birds offer an ideal opportunity to study divorce since they show great variability in the extent to which pair bonds are maintained. However, there has been little consensus as to whether divorce is a behavioural adaptation to improve a mating situation, or a consequence of other processes. Moreover, the biological and ecological correlates of fidelity are difficult to address because previous work has been based on indirect and potentially biased methods. Finally, in terms of process, the link between the process of mate choice and subsequent mating decisions has been largely inaccessible to study. My doctoral thesis addressed these significant gaps in our understanding of cause, process and consequence in the formation and dissolution of pair bonds in socially monogamous birds. I accomplished this in three principal ways. First, I conducted a robust phylogenetic meta-analysis on 84 studies across 64 species to assess the existing empirical evidence that divorce in socially monogamous birds is adaptive (in terms of breeding success). This analysis revealed that divorce is, in general, adaptive as it is both triggered by relatively low breeding success and leads to improvement in success. Next, I developed a novel probabilistic multievent capture–mark–recapture framework that provides joint estimates of survival and fidelity while explicitly accounting for imperfect detection, capture heterogeneity, and uncertainty in pair status. By applying this model to breeding data on a wild great tit population I showed that birds that remain faithful to their partner exhibit higher survival rates and are more likely to remain faithful in the next breeding season than do birds that change partners. Subsequently, I confirmed the generality of a survival benefit by applying the model to breeding data on other tit populations. Then, by applying the model to data from a population of mute swans, I showed that fidelity decreases the likelihood of skipping breeding and mortality in this long-lived species, and that these effects depended on age, individual quality, and immigration status. Finally, I investigated how the timing of pair formation influences breeding success and divorce probability using five years of data on the over-winter social behaviour of great tits. I showed that early pair formation had a positive effect on fitness components, influencing the likelihood of divorce only indirectly, through breeding success. Further, my work revealed that males, but not females, with higher numbers of the female associates in winter, and males whose future breeding partners were ranked low amongst these, divorced more often. My research makes a significant contribution to our understanding of divorce and fidelity, and generates a number of important implications for future studies. First, my work establishes that divorce is adaptive for breeding success. Second, my results highlight that survival is an important (and likely, widespread) fitness consequence of pairing decisions. Third, I provide a novel statistically rigorous modelling framework for estimating fidelity-rates and testing hypothesis about fidelity that overcomes many of the inherent biases in traditional estimates. Fourth, it provides the first evidence for a selective advantage of early pair formation in wild, thus highlighting that there are benefits to pair familiarity that manifest via social associations of individuals prior to breeding. Finally, my work reveals the selective pressures operating via the social environment can ultimately influence the mating strategies individuals adopt.