Péter Péczely

Carotenoids in the egg yolks of collared flycatchers (Ficedula albicollis) in relation to parental quality, environmental factors and laying order

Birds may influence the fitness of their offspring by transmission of different amounts of carotenoids to their eggs. Carotenoids play crucial roles in antioxidant protection and immune defence mechanisms, but they may be available to females in limiting amounts. Therefore, their allocation to the eggs may be influenced by the female’s condition, age and environmental circumstances. Furthermore, the quality of the male parent, which affects the reproductive value of the offspring, may also influence this investment. In this correlational study, we investigated proximate and ultimate factors that may lead to variation in yolk lutein, zeaxanthin and β-carotene concentrations among and within clutches of a wild passerine, the collared flycatcher (Ficedula albicollis). We found that carotenoid concentration was positively associated with caterpillar supply at the time of egg formation, which suggests a proximate constraint of carotenoid availability on yolk composition. Neither female condition, body size, age, nor male plumage ornamentation, age and body size correlated with carotenoid deposition. Yolk β-carotene concentration was found to be positively linked to yolk testosterone concentration. We suggest that females allocated more β-carotene to their eggs to mitigate the potentially detrimental effects of elevated steroid concentration. We found that concentration of β-carotene increased with laying order. The possible function of this pattern may be to enhance the resistance to oxidative stress and pathogens of the disadvantaged last-hatching nestling, suggesting that collared flycatchers pursue a compensatory, “brood survival” strategy.

Common cuckoos (Cuculus canorus) lay eggs with larger yolk but not more testosterone than their great reed warbler (Acrocephalus arundinaceus) hosts

The relatively small common cuckoo Cuculus canorus hatchling evicts its hosts propagules, then begs intensively to elicit sufficient parental care. The proximate mechanisms of these behaviours are still obscure. Recent intraspecific studies on avian broods revealed higher competitive ability of nestlings that hatched from eggs with a greater yolk testosterone level. Greater maternal investment in yolk steroids may provide an explanation for the vigour of parasitic chicks. Unexpectedly we found no evidence of higher yolk T concentration and absolute amount of T in cuckoo eggs compared to those of its host, the great reed warbler Acrocephalus arundinaceus. The yolk mass of cuckoo eggs, however, was significantly greater than that of the host, despite egg volumes being similar between these two species. Relatively larger yolks of cuckoo eggs indicates differential maternal investment strategies by parasites as more yolk may contain additional macronutrients to increase the vigour of parasitic young during the early days of its life and/or to enhance its begging display to elicit care from foster parents.

Seasonal changes in courtship behavior, plasma androgen levels and in hypothalamic aromatase immunoreactivity in male free-living European starlings (Sturnus vulgaris)

In songbirds from temperate latitudes, singing during spring has an essential role in mate attraction, while during the non-breeding season it is connected to territorial aggression and/or maintaining dominance hierarchies or flock cohesion. Courtship behavior is regulated by plasma testosterone (T) levels. Other androgens, like dehydroepiandrosterone (DHEA) could be responsible for aggression. The aromatization of androgens in the brain is an essential step in mediating their effects on behavior. Our goal was to determine whether the seasonal changes in male courtship behavior (measured by average song bout length and wing-waving/flicking) are related to seasonal changes in androgen activity (measured by plasma T, DHEA levels) and aromatase (ARO) immunoreactivity in the preoptic area/medial preoptic nucleus (POA/POM) of free-living male starlings. DHEA increased during pair formation, decreased at nesting and remained at low levels. The number of ARO cells - in line with the T levels - increased during the courtship and nesting periods, but outside the breeding season it was low. Song bout length showed a similar pattern, namely the peak was reached during the courtship period, and after that males stopped singing when chicks started to hatch. Short and fast wing-flicking and wing-waving behavior was observed only during the breading season. Summarizing, we have found that song bout length of male starlings changes parallel with plasma T levels and ARO immunoreactivity in the POA/POM. Furthermore, DHEA levels were low during the sexually inactive period which suggests that other mechanisms could be involved in the aggressive non-courtship behavior/vocalization in these birds.

The influence of parental age and weather on testosterone concentration and offspring survival in broods of tawny owl Strix aluco

Previous research has suggested that parental condition may affect offspring mortality patterns by affecting offspring testosterone levels. Accordingly, we hypothesized that there is a relationship between offspring testosterone concentration and survival during the early nestling period, and that both are influenced by parent age/experience and by prey availability. We tested our hypothesis on tawny owls Strix aluco in their first and third known breeding seasons, when they bred either in adverse or mild weather conditions, in Duna-Ipoly National Park, Hungary. Plasma testosterone concentrations of the nestlings were analyzed and related to parental condition, hatching order and nestling mortality. Inexperienced parents breeding in all weather conditions and experienced parents breeding in adverse conditions were both in poor condition compared to experienced parents breeding in mild conditions. Parents in poor condition produced broods with large between-sibling differences in testosterone concentrations and their later-hatched nestlings (which had low testosterone levels) died during the early nestling period, whereas parents in good condition produced broods with lower variation in offspring testosterone concentrations and all offspring survived the early nestling period. We discuss environmental influences on the amount of testosterone deposited in eggs, and also how maternal testosterone might induce those mechanisms producing testosterone in the nestlings.

Distribution and phenological data of some bird species of Uganda

Abstract During a twenty five days trip in Uganda a brief faunistic survey of birds, mammals and reptiles was performed. Altogether 380 bird species were observed in six National Parks and some other protected areas in the summer of 2012. From these 64 bird species are discussed here selected according the following criteria: rarity, occurrence in a new habitat or geographic area, and emergence of novel breeding phenological data of certain species. Our new records of House Sparrow (Passer domesticus) along the Kazinga Channel (between Lake Edward and Lake George) are outside the current distribution range of the species. The House sparrow expanded its area about 800 km toward west from their first record in Nairobi in 1992. Our new records on White-tailed Ant-thrush (Neocossyphus poensis), Red-tailed Ant-thrush (Neocossyphus rufus), Papyrus Yellow Warbler (Chloropeta gracilirostris), Shelley’s Rufous Sparrow (Passer shelley) and Streaky Seedeater (Serinus striolatus) also require the correction of distribution maps of this species in Uganda. In addition we give some remarks on the breeding phenology of Mountain Wagtail (Motacilla clara), Cassin’s Grey Flycatcher (Muscicapa cassini) and Northern Red Bishop (Euplectes franciscanus). Our recent observational data of African Skimmer (Rynchops flavirostris) may have importance for the Bonn Convention. These observations might be important from conservation and ecotouristic point of views Összefoglalás 2012. július 11. és augusztus 4.-e között 25 napot töltöttünk el Ugandában madarak, hüllők és emlősök megfigyelésével. Utunk során hat nemzeti parkot és számos egyéb védett területet kerestünk fel, összesen 380 madárfajt észleltünk. Közülük 64 fajt válogattunk ki, melyek előfordulási és viselkedési adatainak közzététele érdeklődésre tarthat számot különféle szempontok, mint a természetvédelem, ökoturizmus, költésbiológia alapján, vagy az elterjedési területük változása miatt. A házi veréb (Passer domesticus) kelet-afrikai terjeszkedése során mintegy 10 éve érte el Ugandát, ezért a Kazinga-csatorna melletti megfigyelés jelentős új adatnak számít. További új előfordulási adatok a fehérfarkú hangyarigó (Neocossyphus poensis), a vörösfarkú hangyarigó (Neocossyphus rufus), a papirusz poszáta (Chloropeta gracilirostris), a nílusi veréb (Passer shelley), a csíkos csicsörke (Serinus striolatus) vonatkozásában születtek. Költésbiológiai adatokat közlünk a pataki billegető (Motacilla clara), a cassin-légykapó (Muscicapa cassini) és a tűzhátú szövőmadár (Euplectes franciscanus) vonatkozásában. A részleges vonuló afrikai ollóscsőrűmadár (Rynchops flavirostris) előfordulási adata érdekes lehet a Bonni Egyezmény szempontjából