Physiological responses of host parents to rearing an avian brood parasite: An experimental study

Physiological stress responses to non-mimetic model brood parasite eggs: leukocyte profiles and heat-shock protein Hsp70 levels

“…In conclusion, our results show that the presence of a non-mimetic brood parasite egg in the nest causes significant changes in the cellular immune profiles of adult hosts. These results, together with previous studies on the glucocorticoid response to brood parasite eggs (Ruiz-Raya et al, 2018), as well as evidence from the nestling and fledgling periods (Antonson et al, 2020; Mark and Rubenstein, 2013), indicate that parasitism triggers a generalized stress response affecting multiple physiological components in adult hosts. We encourage the use of different physiological biomarkers in order to gain a comprehensive view of the host physiological response to avian brood parasitism.…”

“…This is consistent with previous studies showing that glucocorticoid levels (CORT or cortisol) and leukocyte profiles (H/L ratio) are not always correlated in wild vertebrates (reviewed in Davis and Maney, 2018). Individual trade-offs between CORT and immune responses (humoral immunity) also appear to be absent in cowbird hosts rearing parasite chicks (Antonson et al, 2020). The lack of correlation between these two measures of physiological stress may be due to differences in the timing of CORT and leukocyte responses to chronic stressors (Davis and Maney, 2018).…”

“…Importantly, short-term changes in H/L ratios may be mediated by glucocorticoids (Sapolsky et al, 2000), although stress hormones and leukocyte profiles are not always correlated (Davis and Maney, 2018). Previous studies have shown that rearing brood parasitic nestlings may cause reduced humoral immune responses in hosts (Antonson et al, 2020), yet the effects of brood parasitism on the components of cell-mediated immunity are still unknown.…”

“…2018; but see Scharf et al . 2021) and nestling stages (Antonson et al, 2020). Parasitized birds also show elevated CORT responsiveness to stressors during the fledgling period, which can lead to detrimental long-term consequences (Mark and Rubenstein, 2013).…”

“…Glucocorticoid hormones are known to mediate allostasis in vertebrates, triggering physiological and behavioural changes that help individuals to cope with environmental challenges (Breuner et al, 2008;Wingfield et al, 1998), including avian brood parasitism (Abolins-Abols and Hauber, 2020). Brood parasitism stimuli is known to increase corticosterone (CORT) levels in adult hosts during incubation (Ruiz-Raya et al 2018; but see Scharf et al 2021) and nestling stages (Antonson et al, 2020). Parasitized birds also show elevated CORT responsiveness to stressors during the fledgling period, which can lead to detrimental long-term consequences (Mark and Rubenstein, 2013).…”