Hoopoes color their eggs with antimicrobial uropygial secretions

  title={Hoopoes color their eggs with antimicrobial uropygial secretions},
  author={Juan Jos{\'e} Soler and Manuel Mart{\'i}n-Vivaldi and Juan Manuel Peralta‐S{\'a}nchez and Laura Rodriguez Arco and Natalia Ju{\'a}rez-Garc{\'i}a-Pelayo},
Uropygial gland secretions are used as cosmetics by some species of birds to color and enhance properties of feathers and teguments, which may signal individual quality. Uropygial secretions also reach eggshells during incubation and, therefore, may influence the coloration of birds’ eggs, a trait that has attracted the attention of evolutionary biologists for more than one century. The color of hoopoe eggs typically changes along incubation, from bluish-gray to greenish-brown. Here, we test… 
Preening as a Vehicle for Key Bacteria in Hoopoes
The hypothesis that symbiotic bacteria are transmitted from the uropygial gland to beak, brood patch, and eggshell surfaces is agreed, opening the possibility that the bacterial community of the secretion plays a central role in determining the communities of special hoopoe eggshell structures that, soon after hatching, are filled with uropgial oil, thereby protecting embryos from pathogens.
Seasonal and Sexual Differences in the Microbiota of the Hoopoe Uropygial Secretion
It is hypothesize that bacterial proliferation may be host-regulated in phases of high infection risk (i.e., nesting) and highlighted the importance of specific antimicrobial-producing bacteria present only in dark secretions that may be key in this defensive symbiosis.
Nest Bacterial Environment Affects Microbiome of Hoopoe Eggshells, but Not That of the Uropygial Secretion
First experimental evidence indicating that nest material influences the bacterial community of the eggshells and, therefore, probability of embryo infection is shown, suggesting a role of nest environments of hoopoes as reservoirs of symbiotic bacteria.
The uropygial gland microbiome of house sparrows with malaria infection
The first results of the Uropygial gland microbiome in malaria-infected birds illustrate the presence of a more specific relationship between certain members of the gland microbiota and Plasmodium parasites in birds, which opens up new questions on the role of the uropygia gland in avian health.
Cosmetic coloration of cross-fostered eggs affects paternal investment in the hoopoe (Upupa epops)
This is the first experimental demonstration that egg colour stained with uropygial secretion could act as a post-mating sexual signal of female quality to males, and males adjusted their provisioning rate to the eggshell cosmetic coloration.
Made-up mouths with preen oil reveal genetic and phenotypic conditions of starling nestlings
It is suggested that the cosmetic use of colored uropygial secretion might also play a role in parent-offspring communication, complementing or amplifying information provided by the flamboyant colored gapes and skin of nestlings.
Acquisition of Uropygial Gland Microbiome by Hoopoe Nestlings
The results of this analysis support the idea that the typical composition of the hoopoe gland microbiome is reached by the incorporation of some bacteria during the nestling period, and suggest the existence of a coevolved core microbiome composed by a mix of specialized vertically transmitted strains and facultative symbionts able to coexist with them.
Environmental Factors Shape the Community of Symbionts in the Hoopoe Uropygial Gland More than Genetic Factors
H hoopoes are able to incorporate new symbionts from the environment during the development of the uropygium, which could be a selective advantage if strains with higher antimicrobial capacity are incorporated into the gland and could aid hosts in fighting against pathogenic and disease-causing microbes.
Preen oil and bird fitness: a critical review of the evidence
  • G. Moreno-Rueda
  • Biology
    Biological reviews of the Cambridge Philosophical Society
  • 2017
The uropygial gland appears to have several non‐mutually exclusive functions in birds, and thus is likely to be subject to several selective pressures, and future studies should consider how the inevitable trade‐offs among different functions drive the evolution of uropyGial gland secretions.
Micro- and macroanatomical features of the uropygial gland of duck (Anas platyrhynchos) and pigeon (Columba livia)
Morphometric and histological analysis of the uropygial gland of the duck and pigeon showed that the architecture is similar among birds; however, some species-specific differences suggest a functional correlation with the habitat.


Special structures of hoopoe eggshells enhance the adhesion of symbiont-carrying uropygial secretion that increase hatching success.
The findings of specialized crypts on the eggshells of hoopoes, and of video-recorded females smearing secretion containing symbiotic bacteria at a high density onto the eggShells strongly support a link between secretion and bacteria on eggs.
Antimicrobial chemicals in hoopoe preen secretions are produced by symbiotic bacteria
Support is found for the hypothesized role of bacteria in the production of such antimicrobial chemicals in hoopoe preen secretions because experimental clearance of bacteria from glands of nestlings with antibiotics resulted in secretions without most of the volatiles detected in control individuals.
Greater flamingos Phoenicopterus roseus use uropygial secretions as make-up
It is shown not only that the colour of feathers of greater flamingos Phoenicopterus roseus became more colourful due to the application of carotenoids from uropygial secretions over the plumage but also that the feathers became more colours with the quantity of pigments applied over them, thus providing evidence of cosmetic coloration.
Symbiotic association between hoopoes and antibiotic- producing bacteria that live in their uropygial gland
A tight symbiotic interaction between bacteria that produce antibiotic substances and the hoopoes is suggested, as well as the association with the presence of bacteria living inside their uropygial gland.
Ectoparasites, uropygial glands and hatching success in birds
Findings are consistent with the hypothesis that the uropygial gland functions to manage the community of microorganisms, and that certain taxa of chewing lice have diverged as a consequence of these defenses.
The evolution of size of the uropygial gland: mutualistic feather mites and uropygial secretion reduce bacterial loads of eggshells and hatching failures of European birds
The size of the uropygial gland was positively related to eggshell bacterial loads, and bird species with higher diversity and abundance of feather mites harboured lower bacterial density on their eggshells (Enterococcus and Staphylococcus), in accordance with the hypothesis.
Seasonal, sexual and developmental differences in hoopoe Upupa epops preen gland morphology and secretions: evidence for a role of bacteria
The results suggest that some of the special properties of hoopoe glands are mediated by the presence of symbiotic bacteria.
Symbiotic bacteria living in the hoopoe's uropygial gland prevent feather degradation
The results suggest that by preening their feathers hoopoes benefit from their symbiotic relationship with bacteriocin-producing enterococci, which constitute a chemical defence against feather degradation.
Feather micro‐organisms and uropygial antimicrobial defences in a colonial passerine bird
It is suggested that the uropygial gland plays a specific role in regulating the abundance of feather-degrading bacteria that furthermore depends on the social environment of the host.
Antimicrobial Activity and Genetic Profile of Enteroccoci Isolated from Hoopoes Uropygial Gland
It is found that the genetic profile of bacterial isolates was related to antimicrobial activity, as well as to individual host identity and the nest from which samples were obtained, suggesting that variation in the inhibitory capacity of Enterococci symbionts should be under selection.