Triparental care in the collared flycatcher ( Ficedula albicollis ): Cooperation of two females with a cuckolded male in rearing a brood

Certain predominant forms of mating and parental care systems are assumed in several model species among birds, but the opportunistic and apparently infrequent variations of “family structures” may often remain hidden due to methodological limitations with regard to genetic or behavioral observations. One of the intensively studied model species, the collared flycatcher (Ficedula albicollis), is usually characterized by social monogamy with polyterritorial, facultative social polygyny, and frequent extrapair mating and extrapair paternity. During a brood-size manipulation experiment, we observed two females and a male delivering food at an enlarged brood. A combination of breeding phenology data (egg laying and hatching date), behavioral data (feeding rates) from video recordings at 10 days of nestling age, and microsatellite genotyping for maternity and paternity suggests a situation of an unrelated female helping a pair in chick rearing. Such observations highlight the relevance of using traditional techniques and genetic analyses together to assess the parental roles within a population, which becomes more important where individuals may dynamically switch from their main and presupposed roles according to the actual environmental conditions

When to measure plumage reflectance: a lesson from Collared Flycatchers Ficedula albicollis

Sexually selected colour traits of bird plumage are widely studied. Although the plumage is replaced only at one or two yearly moults, plumage colour has long been shown to change between moults. Nevertheless, most studies measure colour weeks to months after the courtship period, typically at nestling rearing, and it is unclear whether these measurements yield relevant data concerning the primary process of sexual selection. Here we analyse repeated spectrometric data taken from male Collared Flycatchers during social courtship and nestling rearing. We show that some spectral traits are not correlated between the two measurements and that within-individual correlation declines significantly with the likely exposure of the plumage area to damage and soiling. There is an overall decline in spectral trait exaggeration during breeding, but trait decline is not closely related to measurement latency, especially not in the damage-exposed areas. Finally, sexual selection estimates differ depending on whether they are derived from spectra measured during courtship or during nestling rearing. These results suggest that, contrary to current practice, measurements of plumage reflectance should be made during the primary period of sexual signalling. Spectral trait decline during breeding could also be studied as a possible signal for mates and neighbours.Peer Reviewe

Ornaments and condition: plumage patch sizes, nutritional reserve state, reserve accumulation, and reserve depletion

Abstract: Condition-dependence is considered as a dominant mechanism ensuring the fitness benefits of continued mate choice for heritable sexual signal traits, but crucial questions remain concerning the underlying physiological pathways. For example, it is unclear whether condition-dependence is mediated by the different amount of resource obtained, some uncheatable functional link with nutritional status, or the adverse effect of nutritional stress experienced by some individuals. Furthermore, the pattern of change in nutritional reserves in relation to ornamental traits has recently been proposed as a critical pillar of the condition-dependence concept, but this pattern is virtually unknown in natural populations. We quantified separate measures for actual body condition, lipid reserve accumulation rate, and lipid reserve depletion, and applied these measures to two white plumage ornaments of male collared flycatchers during courtship, during nestling rearing, and before the summer moult. Neither actual condition nor reserve accumulation rate before moult predicted the subsequent change of ornament sizes, but reserve depletion was accompanied by the reduction of forehead patch size to the following year. Wing patch size, a trait important in territoriality, was negatively related to both reserve accumulation and reserve depletion in the courtship period, but not related to current condition. Finally, irrespective of breeding phase, measures of current condition, and recent nutritional reserve depletion were negatively correlated, but both were unrelated to resource accumulation rate. These results indicate that measuring nutritional reserve trajectories in addition to actual condition may reveal functionally important processes underlying signal-condition correlations. Significance statement: Ornamental signal characters are known to convey honest information to signal receivers through their dependence on nutritional condition. Here, we show that such signals can also indicate the temporal trends of condition. We examine plumage patch sizes and separate measures of actual condition, nutritional reserve accumulation, and nutritional reserve depletion in three contexts: during courtship, during nestling rearing, and before the summer moult. The results suggest nutritional stress effects on signal expression, and predictable reserve dynamics in relation to signal expression, thereby highlighting the usefulness of dynamic nutritional measures in clarifying the fundamental concept of condition-dependent signalling.Peer Reviewe

A széncinege tollazati színezete mint egységes jelzésrendszer

Az állatok párválasztási jelzései információt nyújthatnak az egyed minőségéről, de ez az információ igen sokféle lehet. Gyakori egy fajon belül egyszerre több jelzés használata, de a jelzések egymáshoz való viszonya általában tisztázatlan. Különösen ritkán vizsgált kérdés, hogy a különféle jelzések által közvetített információban mennyi a párhuzamosság. Jó példa erre, hogy a madarak különböző eredetű színezeti foltjait, mint a karotinoid alapú és szerkezeti színezet, egymástól függetlennek tételezték fel, korrelációjukat és párhuzamos változásaikat még nem vizsgálták. Jelen munkámban hím és tojó széncinegéken (Parus major) a karotinoid alapú sárga mellszínezet és a szerkezeti alapú fekete fejtetőszínezet fenotípusos integrációját vizsgáltam ősszel (a nyári vedlés után), illetve a tavaszi költési időszakban végzett mintavételek segítségével. Arra voltam kíváncsi, hogy a spektrális adatokból a két testtájra számolt közös főkomponens tengelyek mennyi varianciát magyaráznak, mennyire hasonlóak szezonok és ivarok között, mutatnak-e kondíciófüggést, illetve lehet-e szerepük a szaporodási időszakban. Azt találtam, hogy a két testtáj színezete közt erősebb volt a kapcsoltság tavasszal, mint közvetlenül a vedlés után. A különböző színezeti tengelyek fontosságának megváltozása miatt, amelyet a tollkopás okozhatott, az őszi és tavaszi főtengelyek statisztikailag eltérőnek bizonyultak. A két ivar közt viszont ősszel és tavasszal is hasonlóak voltak a színezeti tengelyek. A sárga mell telítettségét és a fejtető ultraibolya visszaverését összekapcsoló színváltozó ősszel összefüggött a vedléskori kondícióval, tavasszal pedig költéssiker mutatókkal: a hímeknél a költéskezdés idejével, a tojóknál pedig a tojásszámmal. Eredményeink azt mutatják, hogy a különböző eredetű tollazati színek párhuzamosságait érdemes és fontos vizsgálni. Munkánk során egy új statisztikai módszert is teszteltünk a színezeti integráció vizsgálatára

Single tabulated data set

Contains all data used in the analyses published in the paper

Data from: Mutual plumage ornamentation and biparental care: consequences for success in different environments

According to the good parent and differential allocation models, parental behavior could depend on the individual’s own quality, and it could be adjusted to the coinvestor’s parental care and sexual ornamentation. These investment patterns may interact with environmental conditions and offspring quality in determining reproductive success. Few studies have considered ornament-related own and partner care of both parents and their consequences in relation to environmental conditions. In a brood size manipulation experiment on collared flycatchers (Ficedula albicollis), we measured nestling feeding rates, white patch sizes and plumage reflectance properties of both parents, and quantified nestling growth and reproductive success. We found little relationship between ornamentation and own feeding rate irrespective of manipulation. Parental quality, measured as nestling biomass production per unit feeding effort, was related to male structural plumage brightness in a manipulation-dependent manner. Male wing patch size and the female’s structural plumage brightness were linked to the partner’s feeding rate, and this did not vary with experimental environment. Finally, relationship of prefledging nestling size with male forehead patch size was environment-dependent, and this pattern was apparently due to intrinsic nestling characteristics. Reproductive success only partly reflected these findings. Our results indicate how integrated studies of mutual ornamentation and mutual care with environmental and offspring quality may help us better grasp the selection forces shaping sexual ornaments