Excretion patterns of coccidian oocysts and nematode eggs during the reproductive season in Northern Bald Ibis (Geronticus eremita)

Abstract

Individual reproductive success largely depends on the ability to optimize behaviour, immune function and the physiological stress response. We have investigated correlations between behaviour, faecal steroid metabolites, immune parameters, parasite excretion patterns and reproductive output in a critically endangered avian species, the Northern Bald Ibis (Geronticus eremita). In particular, we related haematocrit, heterophil/lymphocyte ratio, excreted immune-reactive corticosterone metabolites and social behaviour with parasite excretion and two individual fitness parameters, namely, number of eggs laid and number of fledglings. We found that the frequency of excretion of parasites’ oocysts and eggs tended to increase with ambient temperature. Paired individuals excreted significantly more samples containing nematode eggs than unpaired ones. The excretion of nematode eggs was also significantly more frequent in females than in males. Individuals with a high proportion of droppings containing coccidian oocysts were more often preened by their partners than individuals with lower excretion rates. We observed that the more eggs an individual incubated and the fewer offspring fledged, the higher the rates of excreted samples containing coccidian oocysts. Our results confirm that social behaviour, physiology and parasite burden are linked in a complex and context-dependent manner. They also contribute background information supporting future conservation programmes dealing with this critically endangered species.

Seasonal differences of corticosterone metabolite concentrations and parasite burden in northern bald ibis (Geronticus eremita): The role of affiliative interactions

“…A previous study on northern bald ibis showed that more nematode eggs were excreted in females than in males during the reproductive season [ 26 ], whereas in the present study it was the other way round. Contrary to this previous study, we did not include the egg-laying phase in the data collection, which may be the reason for not finding an elevated excretion of endoparasite products in females.…”

“…Although individual levels of corticosterone metabolites in parental geese were negatively correlated with the number of offspring [ 19 ], the excretion of nematode eggs increased with family size [ 13 ], indicating that parental effort is costly [ 25 ]. A recent study in northern bald ibis ( Geronticus eremita ) showed that paired individuals excreting high levels of endoparasite products during the reproductive season also engaged in more allopreening behaviour [ 26 ].…”

Investigating individual and social behaviour of the Northern bald ibis (Geronticus eremita): behavioural variety and welfare

“…In the current study, when out of sight the focal ibis was not visible to the observer from the visitor viewing window because the bird was in sheltered areas such as nest boxes, rock crevices or behind trees and bushes. The behavioural ethogram of the study is reported in Table 2 and was prepared basing on preliminary observation of the flock and on previous studies on the Northern bald ibis as well as on relative species ( Hirsch, 1979 ; Kopij, 1998 ; Pegoraro & Föger, 2001 ; Mark, 2007 ; Vargas-Ashby & Pankhurst, 2007 ; Clark et al, 2012 ; Fernández-Juricic, 2012 ; Moulton et al, 2013 ; Frigerio et al, 2016 ).…”

“…Basing on all these indices, a Summary Hygiene Index was created. Following this methodology, after having examined the existing literature, we prepared a list of natural behaviours collected by previous researchers on the NBI as well as on close relative species, in both wild and captive settings ( Hirsch, 1979 ; Kopij, 1998 ; Pegoraro & Föger, 2001 ; Mark, 2007 ; Vargas-Ashby & Pankhurst, 2007 ; Clark et al, 2012 ; Fernández-Juricic, 2012 ; Moulton et al, 2013 ; Frigerio et al, 2016 ). The list included 18 items that were grouped in four subsets basing on the behavioural function ( Table 3 ) ( Kopij, 1998 ).…”

An apparent case of interspecific allopreening by a Royal Spoonbill Platalea regia

“…The altruistic behaviour, allopreening is widespread amongst birds, especially in aggregating species (Waltman and Beissinger 1992;Radford and Du Plessis 2006;Cox 2012;Gill 2012). One obvious benefit is the removal of ectoparasites and maintenance of plumage condition, although close proximity may also aid the transmission of parasites (Frigerio et al 2016). Allopreening also appears to have important social functions, with some studies suggesting it promotes pair bonding (Barbour and Degange 1982), buffers the negative effects of social stress (Scheiber et al 2005;Hennessy et al 2006;Stoẅe et al 2008) and reduces the likelihood of interspecific conflicts and associated breeding failures (Lewis et al 2007).…”