S. Nee, More than meets the eye, Nature, vol.330, issue.6994, pp.804-809, 2004.
DOI : 10.1038/23393

V. Ezenwa, N. Gerardo, D. Inouye, M. Medina, and J. Xavier, Animal Behavior and the Microbiome, Science, vol.338, issue.6104, pp.198-207, 2012.
DOI : 10.1126/science.1227412

H. Consortium, Structure, function and diversity of the healthy human microbiome, Nature, vol.486, issue.7402, pp.207-221, 2012.

V. Torsvik and L. Øvreås, Microbial diversity and function in soil: from genes to ecosystems, Current Opinion in Microbiology, vol.5, issue.3, pp.240-245, 2002.
DOI : 10.1016/S1369-5274(02)00324-7

M. Steinert, U. Hentschel, and J. Hacker, Symbiosis and Pathogenesis: Evolution of the Microbe-Host Interaction, Naturwissenschaften, vol.87, issue.1, pp.1-11, 2000.
DOI : 10.1007/s001140050001

E. Proksch, J. Brandner, and J. Jensen, The skin: an indispensable barrier, Experimental Dermatology, vol.38, issue.12, pp.1063-72, 2008.
DOI : 10.1111/j.1600-0625.2008.00786.x

T. Ganz, Epithelia: Not just physical barriers: Figure 1, Proceedings of the National Academy of Sciences, vol.99, issue.6, pp.3357-3365, 2002.
DOI : 10.1073/pnas.072073199

URL : http://www.ncbi.nlm.nih.gov/pmc/articles/PMC122525

R. Gallo and L. Hooper, Epithelial antimicrobial defence of the skin and intestine, Nature Reviews Immunology, vol.66, issue.7, pp.503-519, 2012.
DOI : 10.1038/nri3228

A. Ellis, Innate host defense mechanisms of fish against viruses and bacteria, Developmental & Comparative Immunology, vol.25, issue.8-9, pp.827-866, 2001.
DOI : 10.1016/S0145-305X(01)00038-6

E. Burtt and J. Ichida, Occurrence of Feather-Degrading Bacilli in the Plumage of Birds, The Auk, vol.116, issue.2, pp.364-72, 1999.
DOI : 10.2307/4089371

M. Shawkey, S. Pillai, G. Hill, L. Siefferman, and S. Roberts, Bacteria as an Agent for Change in Structural Plumage Color: Correlational and Experimental Evidence, The American Naturalist, vol.169, issue.S1, pp.112-133, 2007.
DOI : 10.1086/510100

J. Swaddle, M. Witter, I. Cuthill, A. Budden, and P. Mccowen, Plumage Condition Affects Flight Performance in Common Starlings: Implications for Developmental Homeostasis, Abrasion and Moult, Journal of Avian Biology, vol.27, issue.2, pp.103-114, 1996.
DOI : 10.2307/3677139

D. Clayton, Feather-Busting Bacteria, The Auk, vol.116, issue.2, pp.302-306, 1999.
DOI : 10.2307/4089364

A. Gunderson, FEATHER-DEGRADING BACTERIA: A NEW FRONTIER IN AVIAN AND HOST???PARASITE RESEARCH?, The Auk, vol.125, issue.4, pp.972-981, 2008.
DOI : 10.1525/auk.2008.91008

M. Shawkey, S. Pillai, and G. Hill, Chemical warfare? Effects of uropygial oil on feather-degrading bacteria, Journal of Avian Biology, vol.33, issue.4, pp.345-354, 2003.
DOI : 10.1111/j.0908-8857.2003.03193.x

M. Ruiz-rodriguez, E. Valdivia, J. Soler, M. Martin-vivaldi, A. Martin-platero et al., Symbiotic bacteria living in the hoopoe's uropygial gland prevent feather degradation, Journal of Experimental Biology, vol.212, issue.22, pp.3621-3627, 2009.
DOI : 10.1242/jeb.031336

J. Reneerkens, M. Versteegh, A. Schneider, T. Piersma, and E. Burtt, ) FLEXIBLE DEFENSE AGAINST FEATHER-DEGRADING BACTERIA?, The Auk, vol.125, issue.2, pp.285-90, 2008.
DOI : 10.1525/auk.2008.06217

S. Leclaire, P. Pierret, M. Chatelain, and J. Gasparini, Feather bacterial load affects plumage condition, iridescent color, and investment in preening in pigeons, Behavioral Ecology, vol.25, issue.5, pp.1192-1200, 2014.
DOI : 10.1093/beheco/aru109

S. Jacob, A. Immer, S. Leclaire, N. Parthuisot, C. Ducamp et al., Uropygial gland size and composition varies according to experimentally modified microbiome in Great tits, BMC Evolutionary Biology, vol.14, issue.1, p.134, 2014.
DOI : 10.1186/1471-2148-14-134

URL : https://hal.archives-ouvertes.fr/hal-01310939

A. Salibian and D. Montalti, Physiological and biochemical aspects of the avian uropygial gland, Brazilian Journal of Biology, vol.69, issue.2, pp.437-483, 2009.
DOI : 10.1590/S1519-69842009000200029

D. Goldstein, Estimates of Daily Energy Expenditure in Birds: The Time-Energy Budget as an Integrator of Laboratory and Field Studies, American Zoologist, vol.28, issue.3, pp.829-873, 1988.
DOI : 10.1093/icb/28.3.829

S. Redpath, Vigilance levels in preening Dunlin Calidris alpina, Ibis, vol.31, issue.6, pp.555-562, 1988.
DOI : 10.1111/j.1474-919X.1988.tb02723.x

R. Piault, J. Gasparini, P. Bize, M. Paulet, K. Mcgraw et al., Experimental support for the makeup hypothesis in nestling tawny owls

N. Yorinks and C. Atkinson, EFFECTS OF MALARIA ON ACTIVITY BUDGETS OF EXPERIMENTALLY INFECTED JUVENILE APAPANE (HIMATIONE SANGUINEA), The Auk, vol.117, issue.3, pp.731-739, 2000.
DOI : 10.1642/0004-8038(2000)117[0731:EOMOAB]2.0.CO;2

M. Otto, Staphylococcus epidermidis ??? the 'accidental' pathogen, Nature Reviews Microbiology, vol.271, issue.8, pp.555-67, 2009.
DOI : 10.1038/nrmicro2182

P. Pap, G. Czirják, C. Vágási, Z. Barta, and D. Hasselquist, Sexual dimorphism in immune function changes during the annual cycle in house sparrows, Naturwissenschaften, vol.26, issue.10, pp.891-901, 2010.
DOI : 10.1007/s00114-010-0706-7

G. Demas, D. Zysling, B. Beechler, M. Muehlenbein, and S. French, Beyond phytohaemagglutinin: assessing vertebrate immune function across ecological contexts, Journal of Animal Ecology, vol.23, issue.Suppl 4, pp.710-740, 2011.
DOI : 10.1111/j.1365-2656.2011.01813.x

R. Boughton, G. Joop, and S. Armitage, Outdoor immunology: methodological considerations for ecologists, Functional Ecology, vol.8, issue.1, pp.81-100, 2011.
DOI : 10.1111/j.1365-2435.2010.01817.x

M. Vinkler, H. Bainová, and T. Albrecht, Functional analysis of the skin-swelling response to phytohaemagglutinin, Functional Ecology, vol.3, issue.5, pp.1081-1087, 2010.
DOI : 10.1111/j.1365-2435.2010.01711.x

K. Matson, R. Ricklefs, and K. Klasing, A hemolysis???hemagglutination assay for characterizing constitutive innate humoral immunity in wild and domestic birds, Developmental & Comparative Immunology, vol.29, issue.3, pp.275-86, 2005.
DOI : 10.1016/j.dci.2004.07.006

B. Tieleman, J. Williams, R. Ricklefs, and K. Klasing, Constitutive innate immunity is a component of the pace-of-life syndrome in tropical birds, Proceedings of the Royal Society B: Biological Sciences, vol.32, issue.1, pp.1715-1735, 1573.
DOI : 10.1146/annurev.ecolsys.32.081501.114006

M. Vinkler, J. Svobodová, B. Gabrielová, H. Bainová, and A. Bryjová, Cytokine expression in phytohaemagglutinin-induced skin inflammation in a galliform bird, Journal of Avian Biology, vol.278, issue.1, pp.43-50, 2013.
DOI : 10.1111/j.1600-048X.2011.05860.x

C. Salaberria, M. J. De-luna, M. Gil, D. Puerta, and M. , The PHA Test as an Indicator of Phagocytic Activity in a Passerine Bird, PLoS ONE, vol.300, issue.12, p.84108, 2013.
DOI : 10.1371/journal.pone.0084108.t003

K. Klasing and T. Leshchinsky, Functions, costs, and benefits of the immune system during development and growth, Ostrich, vol.69, pp.2817-2849, 1999.

G. Moreno-rueda, Experimental test of a trade-off between moult and immune response in house sparrows Passer domesticus, Journal of Evolutionary Biology, vol.160, issue.10, pp.2229-2266, 2010.
DOI : 10.1111/j.1420-9101.2010.02090.x

T. Martin, E. Arriero, and A. Majewska, A trade-off between embryonic development rate and immune function of avian offspring is revealed by considering embryonic temperature, Biology Letters, vol.67, issue.3, pp.425-433, 2011.
DOI : 10.1093/bioinformatics/11.3.247

P. Pap, C. Vagasi, G. Czirjak, A. Titilincu, A. Pintea et al., ), The Auk, vol.128, issue.2, pp.330-339, 2011.
DOI : 10.1525/auk.2011.10142

K. Schneeberger, A. Courtiol, G. Czirják, and C. Voigt, Immune Profile Predicts Survival and Reflects Senescence in a Small, Long-Lived Mammal, the Greater Sac-Winged Bat (Saccopteryx bilineata), PLoS ONE, vol.6, issue.9, p.108268, 2014.
DOI : 10.1371/journal.pone.0108268.s001

B. Beechler, H. Broughton, A. Bell, V. Ezenwa, and A. Jolles, ): Associations with Parasite Infection and White Blood Cell Counts, Physiological and Biochemical Zoology, vol.85, issue.3, pp.255-64, 2012.
DOI : 10.1086/665276

R. Berg, Bacterial translocation from the gastrointestinal tract, Trends in Microbiology, vol.3, issue.4, pp.149-54, 1995.
DOI : 10.1016/S0966-842X(00)88906-4

A. Ochsenbein and R. Zinkernagel, Natural antibodies and complement link innate and acquired immunity, Immunology Today, vol.21, issue.12, pp.624-654, 2000.
DOI : 10.1016/S0167-5699(00)01754-0

N. Baumgarth, O. Herman, G. Jager, L. Brown, L. Herzenberg et al., Innate and acquired humoral immunities to influenza virus are mediated by distinct arms of the immune system, Proceedings of the National Academy of Sciences, vol.96, issue.5, pp.2250-2255, 1999.
DOI : 10.1073/pnas.96.5.2250

D. Coster, G. Verhulst, S. Koetsier, E. , D. Neve et al., Effects of early developmental conditions on innate immunity are only evident under favourable adult conditions in zebra finches, Naturwissenschaften, vol.208, issue.12, pp.1049-56, 2011.
DOI : 10.1007/s00114-011-0863-3

D. Buehler, F. Encinas?viso, M. Petit, F. Vézina, B. Tieleman et al., Limited Access to Food and Physiological Trade???Offs in a Long???Distance Migrant Shorebird. II. Constitutive Immune Function and the Acute???Phase Response, Physiological and Biochemical Zoology, vol.82, issue.5, pp.561-71, 2009.
DOI : 10.1086/603635

J. Moreno, J. Sanz, and E. Arriero, Reproductive effort and T-lymphocyte cell-mediated immunocompetence in female pied flycatchers Ficedula hypoleuca, Proceedings of the Royal Society B: Biological Sciences, vol.266, issue.1424, pp.1105-1114, 1424.
DOI : 10.1098/rspb.1999.0750

P. Ilmonen, T. Taarna, and D. Hasselquist, Are incubation costs in female pied flycatchers expressed in humoral immune responsiveness or breeding success?, Oecologia, vol.130, issue.2, pp.199-204, 2002.
DOI : 10.1007/s004420100804

R. Johnston and M. Janiga, Feral pigeons, 1995.

L. Jacquin, P. Lenouvel, C. Haussy, S. Ducatez, and J. Gasparini, Melanin-based coloration is related to parasite intensity and cellular immune response in an urban free living bird: the feral pigeon Columba livia, Journal of Avian Biology, vol.269, issue.1, 2011.
DOI : 10.1111/j.1600-048X.2010.05120.x

L. Jacquin, C. Haussy, C. Bertin, K. Laroucau, and J. Gasparini, Darker female pigeons transmit more specific antibodies to their eggs than do paler ones, Biological Journal of the Linnean Society, vol.108, issue.3, pp.647-57, 2013.
DOI : 10.1111/bij.12001

A. Møller, G. Czirjak, and P. Heeb, Feather micro-organisms and uropygial antimicrobial defences in a colonial passerine bird, Functional Ecology, vol.6, issue.6, pp.1097-102, 2009.
DOI : 10.1111/j.1365-2435.2009.01594.x

J. Smits, G. Bortolotti, and J. Tella, Simplifying the phytohaemagglutinin skin-testing technique in studies of avian immunocompetence, Functional Ecology, vol.13, issue.4, pp.567-72, 1999.
DOI : 10.1007/s004420050522

A. Møller and C. Haussy, Fitness consequences of variation in natural antibodies and complement in the Barn Swallow Hirundo rustica, Functional Ecology, vol.152, issue.2, pp.363-71, 2007.
DOI : 10.1098/rspb.2005.3396

K. Matson, B. Tieleman, and K. Klasing, Capture Stress and the Bactericidal Competence of Blood and Plasma in Five Species of Tropical Birds, Physiological and Biochemical Zoology, vol.79, issue.3, pp.556-64, 2006.
DOI : 10.1086/501057

S. Millet, J. Bennett, K. Lee, M. Hau, and K. Klasing, Quantifying and comparing constitutive immunity across avian species, Developmental & Comparative Immunology, vol.31, issue.2, pp.188-201, 2007.
DOI : 10.1016/j.dci.2006.05.013

A. Petroianu, R. Da-silva, V. Cardoso, L. Alberti, and M. Da-silva, Effect of spleen surgeries on Escherichia coli distribution on the mononuclear phagocytic system, International Journal of Surgery, vol.8, issue.1, pp.48-51, 2010.
DOI : 10.1016/j.ijsu.2009.10.006

I. Sas-intitute, SAS user's guide, version 8, 1999.