Nest Material Shapes Eggs Bacterial Environment (original) (raw)
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Aromatic plants in nests of the blue tit Cyanistes caeruleus protect chicks from bacteria
Oecologia, 2009
Several bird species add fresh fragments of plants which are rich in volatile secondary compounds to their nests. It has been suggested, although never tested, that birds use fresh plants to limit the growth of nest microorganisms. On Corsica, blue tits (Cyanistes caeruleus) incorporate fresh fragments of aromatic plants into their nests. These plants do not reduce infestation by nest ectoparasites, but have been shown to improve growth and condition of chicks at fledging. To understand the mechanisms underlying such benefits, we experimentally tested the effects of these plants on the bacteria living on blue tits. Aromatic plants significantly affected the structure of bacterial communities, in particular reducing bacterial richness on nestlings. In addition, in this population where there is a strong association between bacterial density and infestation by blood-sucking Protocalliphora blow fly larvae, these plants reduced bacterial density on the most infested chicks. Aromatic plants had no significant effect on the bacteria living on adult blue tits. This study provides the first evidence that fresh plants brought to the nests by adult birds limit bacterial richness and density on their chicks.
Plumage bacterial load increases during nest-building in a passerine bird
Journal of Ornithology, 2012
ABSTRACT Plumage bacteria may play an important role in shaping the life histories of birds. However, few studies have examined natural patterns of variation in plumage bacteria. We have previously shown that plumage bacterial load is higher during the pre-laying period than during the brood rearing period in female Great Tits (Parus major). Here, we examined whether the pre-laying bacterial peak in female Great Tits develops during nest-building, where the females come into increased contact with the ground and nest materials, or dates back to an earlier period. Females were captured during three stages of nest-building (nest initiated, nest half ready, and nest completed). The density of plumage bacteria and the species richness of feather-degrading bacterial assemblages were studied using flow cytometry and ribosomal intergenic spacer analysis (RISA), respectively. The density of attached bacteria on feathers increased significantly between nest initiation and nest completion. No effect of nest-building stage on feather-degrading bacterial species richness was found. Our results indicate that the density of attached bacteria in the plumage of free-living birds can change rapidly during nest-building, providing one potential cost of nest-building for individual birds.
Use of nest material as insecticidal and anti-pathogenic agents by the European Starling
Oecologia, 1985
Passerine birds that reuse nest sites face an increased parasite and pathogen load. They also are more likely to use fresh green vegetation during nest construction. The present results demonstrate that at least one passerine, the European Starling: (a) selects a small subset of available plant species for inclusion in nest material; and (b) chooses plants whose volatiles are more likely to inhibit arthropod hatching and bacterial growth relative to a random subset of available vegetation. The results also show that preferred plants possess greater numbers of mono- and sesqueter-penes at higher concentrations relative to a random subset of available plants. These findings strongly suggest that starlings use chemicals in fresh vegetation as fumigants against parasites and pathogens.
Naturwissenschaften, 2010
Avian incubation dramatically reduces the abundance and diversity of microbial assemblages on eggshells, and this effect has been hypothesized as an adaptive explanation for partial incubation, the bouts of incubation that some birds perform during the egg-laying period. However, the mechanisms for these antimicrobial effects are largely unknown. In this study, we hypothesized that microbial inhibition is partly achieved through removal of liquid water, which generally enhances microbial growth, from eggshells, and experimentally tested this hypothesis in two ways. First, we placed the first-and second-laid eggs of tree swallow (Tachycineta bicolor) clutches in unincubated holding nests with either ambient or increased water on eggshells. Second, we added water to eggshells in naturally partially incubated nests. We compared microbial growth on shells during a 5-day experimental period and found that, as predicted, both unincubated groups had higher microbial growth than naturally partially incubated controls, and that only in the absence of incubation did wetted eggs have higher microbial growth than unwetted eggs. Thus, we have shown that water increases microbial growth on eggshells and that incubation nullifies these effects, suggesting that removal of water from egg surfaces is one proximate mechanism for the antimicrobial effects of incubation.
Journal of Ornithology, 2003
We investigated the bacterial frequency and identified 11 genera of bacteria in starlingnests of a nest box colony in southern Germany. We sampled bacteria with a new method: agar paddles, developed for the food industry, were pressed against the naked belly of nestlings at an age of 14 days for 5 seconds. The bacteria colonies on the paddle surface were counted after incubation and their numbers served as an estimate of bacterial infestation of a nest. Bacteria numbers increased with season and precipitation. No relationship between bacteria load of the nests and hatching and fledging success, nestling mortality and body mass close to fledging was detected. The reason for this may be that a high bacteria load is not necessarily harmful but may even act in a beneficial way on the digestive and immune system. Nevertheless we consider it possible that the higher load of bacteria of late nests may under certain conditions be one of the factors responsible for the frequently observed lower quality of second brood nestlings.
Mechanisms of antimicrobial defense in avian eggs
One of the greatest threats to the survival of avian eggs is the risk of infection by microbes; as such, a large number of parental defense mechanisms have evolved in response to the decreased fitness imposed by microbial infection. The existing literature on this topic has focused largely on the mechanisms of microbial invasion through eggshells and the identification of molecules with antimicrobial properties in eggs of commercial species. However, little is still known about antimicrobial mechanisms in wild birds or how they vary with environmental pressures. This review concentrates on recent findings that shed new light on the role of parental behaviors (including incubation and placement of vegetation with antifungal activity in the nest) and the physical properties of eggshells (including nanometer-scale spheres that prevent microbial attachment) that protect eggs from contamination in high-risk environments. In addition to presenting a summary of current information, we identify evident gaps in knowledge and highlight research avenues for the future.
Journal of Ornithology
Nests of secondary-cavity breeding birds are structures constructed to lay and incubate eggs and raise nestlings to fledging. These nests are characterized by relatively stable conditions, which makes them a suitable habitat for various microorganisms. It has been suggested that bacteria inhabiting nests and nestling skin may affect nestlings both positively and negatively. In this study, nests of Great Tits Parus major were replaced with artificial nests on the fifth day of the nestling phase in two different study sites to create two categories of nests: (i) natural and (ii) artificial with a reduced bacterial load. Four days later, bacterial samples were collected from the nestling skin and from the edge of the nest to assess skin and nest bacterial loads, expressed as colony forming units (CFUs). It was predicted that (i) the previous season occupancy of nest boxes would influence bacterial loads, (ii) the experimental treatment would reduce nest and skin bacterial loads, and (i...
Between laying and hatching, eggs are colonized by a variety of micro-organisms able to invade the eggshell and infect egg contents, posing risks to embryo viability. However, little is known about the specific microbial communities colonizing eggshells in free-living species, or their sources. We investigated potential changes in the bacterial community structure on eggs of a free-living bird species (red-capped lark, Calandrella cinerea), using eggs from the start of laying until hatching, and associated them with communities found in the maternal cloaca and soil surrounding nests. Eggshell and soil communities were distinct, while cloacal and eggshell communities showed significant overlap, and cloaca and soil communities were strongly similar. Neither bacterial structure nor diversity, abundance or species richness changed over the duration of incubation. Our results support previous findings that incubation inhibits bacteria growth and has overall bacteriostatic effects, and that eggshells receive bacteria from maternal cloacae during laying.
Journal of Ornithology, 2018
The Blue Tit Cyanistes caeruleus prefer to use nest boxes to raise their young rather than nests in natural tree cavities. However, nest boxes provide a warm, humid microclimate that is favourable to the growth of rich bacterial communities. In this study we investigated how the bacterial community developed throughout the breeding season and whether it had any effect on egg or nestling mortality. Samples were collected across six sites and three breeding seasons at the completion of nest building, clutch completion and immediately post fledging. Bacterial counts were obtained for each sample, including a total bacterial count using non-selective media and bacterial counts on selective media for Staphylococcus spp. and Enterobacter spp, which may indicate pathogenicity to the birds. There were significantly more bacteria (total counts and counts for Staphylococcus spp. and Enterobacter spp. specifically) present within the nest box at the post fledging stage compared to the two earlier stages, likely due to increased activity by the adult birds (feeding of the nestlings and defecating) and less time by the adult birds for self-preening and nest sanitation. No positive relationship was found between bacterial counts and either egg mortality, nestling mortality or brood size; however, a negative relationship between egg mortality and total bacterial count was identified. Although somewhat unexpected, this negative relationship may indicate the presence of a greater number of symbiotic bacteria, which could offer a greater level of protection. Keywords Bacteria • Birds • Nest • Breeding • Success Zusammenfassung Wachsende Belastung durch Bakterien in Nistkästen von Blaumeisen während der Brutzeit und ihr möglicher Einfluss auf Schlüpfen und Flüggewerden Blaumeisen (Cyanistes caeruleus) ziehen für die Aufzucht ihrer Jungen Nistkästen den natürlichen Baumhöhlen vor. Aber die Nistkästen bieten ein warmes und feuchtes Mikroklima, das die Entwicklung von Bakteriengemeinschaften fördert. In dieser Studie wurde untersucht, wie sich die Bakteriengemeinschaften während der Brutzeit entwickelten und ob sie einen Einfluss auf die Sterberate der Nestlinge oder das Absterben der Eier hatten. Über drei Brutzeiten und sechs Brutplätze hinweg wurden während des Nestbaus, der Vervollständigung des Geleges und unmittelbar nach Ausfliegen der Jungen Proben gesammelt und für jede Probe die darin enthaltenen Bakterien gezählt. Zum einen wurde mit unspezifischen Nährmedien die Gesamtzahl ermittelt, zum anderen anhand von spezifischen Medien die Anzahl von Staphylococcus spp. und von Enterobacter spp., die beide als Hinweis auf bakterielle Pathogenität für die Vögel genommen werden können. Nach dem Ausfliegen gab es in den Nistkästen signifikant mehr Bakterien (insgesamt, sowie auch Staphylococcus spp. und Enterobacter spp.), vermutlich wegen der erhöhten Aktivität für das Füttern der Jungen und Entfernen der Kotballen und der entsprechend weniger verfügbaren Zeit für das Putzen der Nester und der Adulten selbst. Ein positiver Zusammenhang mit der Gelegegröße oder der Sterberate von Nestlingen oder Eiern konnte nicht festgestellt werden, wohl aber eine negative Beziehung zwischen der Gesamtzahl an Bakterien und der Absterberate der Eier. Obwohl etwas unerwartet, könnte dies ein Hinweis auf eine größere Anzahl symbiontischer Bakterien sein, die möglicherweise einen größeren Schutz bieten. Communicated by K. C. Klasing.