Egg Speckling Patterns Do Not Advertise Offspring Quality or Influence Male Provisioning in Great Tits

Many passerine birds lay white eggs with reddish brown speckles produced by protoporphyrin pigment. However, the function of these spots is contested. Recently, the sexually selected eggshell coloration (SSEC) hypothesis proposed that eggshell color is a sexually selected signal through which a female advertises her quality (and hence the potential quality of her future young) to her male partner, thereby encouraging him to contribute more to breeding attempts. We performed a test of the SSEC hypothesis in a common passerine, the great tit Parus major. We used a double cross-fostering design to determine whether males change their provisioning behavior based on eggshell patterns they observe at the nest. We also tested the assumption that egg patterning reflects female and/or offspring quality. Because birds differ from humans in their color and pattern perception, we used digital photography and models of bird vision to quantify egg patterns objectively. Neither male provisioning nor chick growth was related to the pattern of eggs males observed during incubation. Although heavy females laid paler, less speckled eggs, these eggs did not produce chicks that grew faster. Therefore, we conclude that the SSEC hypothesis is an unlikely explanation for the evolution of egg speckling in great tits

Connecting the data landscape of long-term ecological studies: The SPI-Birds data hub

The integration and synthesis of the data in different areas of science is drastically slowed and hindered by a lack of standards and networking programmes. Long-term studies of individually marked animals are not an exception. These studies are especially important as instrumental for understanding evolutionary and ecological processes in the wild. Furthermore, their number and global distribution provides a unique opportunity to assess the generality of patterns and to address broad-scale global issues (e.g. climate change). To solve data integration issues and enable a new scale of ecological and evolutionary research based on long-term studies of birds, we have created the SPI-Birds Network and Database (www.spibirds.org)\u2014a large-scale initiative that connects data from, and researchers working on, studies of wild populations of individually recognizable (usually ringed) birds. Within year and a half since the establishment, SPI-Birds has recruited over 120 members, and currently hosts data on almost 1.5 million individual birds collected in 80 populations over 2,000 cumulative years, and counting. SPI-Birds acts as a data hub and a catalogue of studied populations. It prevents data loss, secures easy data finding, use and integration and thus facilitates collaboration and synthesis. We provide community-derived data and meta-data standards and improve data integrity guided by the principles of Findable, Accessible, Interoperable and Reusable (FAIR), and aligned with the existing metadata languages (e.g. ecological meta-data language). The encouraging community involvement stems from SPI-Bird's decentralized approach: research groups retain full control over data use and their way of data management, while SPI-Birds creates tailored pipelines to convert each unique data format into a standard format. We outline the lessons learned, so that other communities (e.g. those working on other taxa) can adapt our successful model. Creating community-specific hubs (such as ours, COMADRE for animal demography, etc.) will aid much-needed large-scale ecological data integration

Negotiation over offspring care?--a positive response to partner-provisioning rate in great tits

Game theoretical models of biparental care predict that a change in work rate by one parent should be met by incomplete compensation by its partner. However, in empirical studies on biparental birds, there has been some inconsistency in the direction and extent of the response, and the mechanism behind it has so far been unclear. Parents could be responding directly to partner work rate or indirectly via chick begging. In this study of great tits (Parus major), the work rate of one parent was increased experimentally by augmenting the begging of the chicks with playback of extra begging calls whenever the parent visited the nest. The playback had no effect on the chicks' begging behavior, so any change in the focal parent's behavior was a direct response to its partner's work rate over a short timescale. An experimental increase in care by either male or female parent led to an increase (to a lesser extent) in the work rate of its partner, which is counter to the decrease predicted by partial compensation models. This seemingly paradoxical result may reflect decisions made exclusively over a short timescale and is in keeping with new theoretical work, which takes into account the information content of partner work rates. Copyright 2006.begging; great tit; matching; parental care; partial compensation; playback; provisioning rate

Maternal anxiety, maternal sensitivity, and attachment

Previous research has related maternal anxiety to insecurity of attachment. Here we ask whether different aspects of maternal sensitivity mediate this link. From a community sample of intact families with 1-3 children, mothers with 4.5-year-olds were selected for low, medium, or high anxiety levels (N=98). Following Mary Ainsworth’s lead, our maternal sensitivity measures were primarily based on ratings of direct observations. Six sets of measures were obtained: positive maternal style at home (a mean of 4 different ratings); providing a sensitive framework, limit setting, allowing autonomy, criticizing/cutting in (each a mean relative frequency over two laboratory joint tasks); and tension-making (a mean of 3 different ratings in a fear-inducing task). Regression analyses showed firstly that maternal anxiety rather than behavioral inhibition or sex of child was the significant predictor of each maternal sensitivity measure; and secondly that these measures rather than maternal anxiety or sex were the significant predictors of security of attachment. Finally, ANOVA’s indicated which sets of maternal ratings were associated with each pattern of attachment (Avoidant, Secure, Ambivalent, or Controlling)

Parental-Offspring Conflict

Disputes between parents and their young might seem easy enough to spot in everyday human life, but the notion of a general, evolutionary conflict between offspring and their parents has proved surprisingly slippery (reviewed by Godfray 1995). Nevertheless, today, almost four decades since the concept was first proposed by Trivers (1974), parent-offspring conflict has theoretically robust foundations (reviewed by Godfray 1995; Godfray and Johnstone 2000) and there is diverse evidence that it is a significant selective force in nature (although perhaps not always in the ways initially assumed, reviewed by Kilner and Hinde 2008). In a recent review, we showed how information warfare lies at the heart of parent-offspring conflict in many instances. Readers specifically interested in signalling by young animals and their parents, as well as other uses of personal information, may wish to consult Kilner and Hinde 2008 before ploughing ahead here. Our aim in this chapter is to attempt to reconstruct the evolutionary consequences of this conflict for traits in offspring and their parents, focusing relatively little on signalling this time. We start with a quick recap of basic conflict theory before outlining diverse empirical evidence for an evolutionary conflict between parents and their young. Next we consider how conflict might link pairs of traits in parents and their offspring, showing how co-evolution between the two parties becomes focused on these particular characters. We conclude with a discussion about the outcomes of parent-offspring conflict: does it always end in a stable equilibrium between parents and their young, as predicted by the many ‘resolution’ models of conflict? Or is instability widespread, with parents and offspring frequently alternating in who gains the upperhand

Long-term familiarity promotes joining in neighbour nest defence

Familiarity plays an important role in the evolution of sociality and cooperation. Familiar individuals may gain a reputation for participating in, or defecting from, cooperative tasks. Previous research suggests that long-term familiarity with territorial neighbours benefits breeders. We tested the hypothesis that great tits (Parus major) are more likely to join in neighbours' nest defence if those neighbours are familiar from the previous year. We show that neighbours that shared a territory boundary the previous year are more likely to join their neighbours' nest defence than neighbours that did not share a boundary before. Closer neighbours did not differ from distant neighbours in their latency to join. For familiar neighbours that joined, there was no difference in call rate in relation to whether one or both members of the focal pair were familiar. First-time breeders (by definition unfamiliar) did not join each other's nest defence. This is the first evidence of a relationship between familiarity and joining in nest defence. Such direct benefits of familiarity may have important implications in the evolution of sociality

Begging signals more than just short-term need: cryptic effects of brood size in the pied flycatcher (Ficedula hypoleuca)

The begging of nestling birds is known to reliably signal short-term nutritional need, which is used by parents to adjust rates of food delivery and patterns of food distribution within broods. To test whether begging signals reflect more than just short-term feeding history, we experimentally created 18 "small" (4-nestling) and 18 "large" (8-nestling) broods in the pied flycatcher (Ficedula hypoleuca). Compared to small broods, large broods were provisioned by parents at a greater rate, but at a lower visit rate per nestling and with no obvious differences in load mass per visit. However, lower rates of food mass delivery per nestling in large broods did not result in any measurable reduction in nestling growth (i.e. "long-term need") or in any increase in the begging effort per individual nestling whilst in the nest. Mid-way through the nestling period we also used hand-feeding laboratory trials to assess in more detail individual begging behaviour and digestive performance of the three mid-ranking nestlings from each brood. More food items were required at the start of each trial to satiate nestlings from large broods, but despite this initial control for "short-term need", nestlings from large broods went on to beg at consistently higher rates and at different acoustic frequencies. Large brood nestlings also produced smaller faecal sacs, which were quantitatively different in content but did not differ in frequency. We suggest that different nutritional histories can produce cryptic changes in nestling digestive function, and that these can lead to important differences in begging signals despite controlling for short term need. [KEYWORDS: Brood size - Nestling begging - Parental care - Pied flycatcher - Signals of need]