Ketone body levels in wintering great tits Parus major in sites differing in artificial food availability

Abstract

Ketone body levels, among other biochemical blood indices, are important indicators of the physiological condition of birds. Plasma ketone as an indicator of fasting and lipid use is strongly linked to demanding phases in the avian life cycle, such as migration or wintering. The main goal of this study was to check whether ketone body levels differ between the habitats in which individuals stay in winter. To test the above prediction, we used a portable point-of-care device to measure ketone body levels in wintering great tits (Parus major). We assumed that wintering in distinct habitats that differ structurally, particularly with respect to food availability, would affect the metabolic performance of birds and their physiological condition. Individual great tits were trapped in mist nets and blood-sampled in three distinct locations within the city: an urban parkland, the deciduous forest and a city centre. As expected, we showed that the mean ketone level was significantly higher in the area where artificial feeding was irregular than in two areas of regular feeding, indicating the more intense fasting state there. We also checked if the level of ketone bodies differs with respect to the sex of an individual, but we found no such difference.

Using point‐of‐care devices to examine covariation among blood nutritional‐physiological parameters and their relationships with poxvirus infection, habitat urbanization, and male plumage coloration in house finches (Haemorhous mexicanus)

“…Previous studies found that POC‐measured blood parameters in one or several bird species were also comparable to traditional laboratory assays, even though POC testing devices had slightly higher values compared with the laboratory tests (Beattie et al, 2022; Morales et al, 2020). Our results had similar value ranges (Supporting Information S1: Table 2) compared with many other studies of different passerine species (Beattie et al, 2022; Dulisz et al, 2021; Gadau et al, 2019; Glądalski et al, 2018; Kaliński et al, 2014, 2022; Lieske et al, 2002; McGraw et al, 2020; Morales et al, 2020), which makes POC devices affordable and accessible tools that could be used to study life‐history and blood nutritional physiological parameters in other wild animals. We note that POC devices can measure other hematological variables, such as cholesterol, electrolytes, and hemoglobin concentrations (Livingston et al, 2022; Morales et al, 2020; Sahoo et al, 2022), and we encourage other studies to investigate these additional blood parameters to understand the full efficacy and utility of POC devices with wildlife species.…”

“…and about key fitness variables or proxies (e.g., sex, survival, disease). In the aforementioned study of house sparrows, for example, authors found that, when exposed to stress, house sparrows increased glucose and ketone levels (Beattie et al, 2022), which was similar to a study in great tits (Parus major; Kaliński et al, 2022). Glucose and triglyceride concentrations are often associated with overall energy intake (Alonso-Alvarez & Ferrer, 2001;Jackson et al, 2023), but ketones are usually related to lipid utilization and fasting (Castellini & Rea, 1992) and may be considered as a proxy for total mass loss in birds (Alonso-Alvarez & Ferrer, 2001).…”

Hepatic lipid accumulation is associated with multiple metabolic pathway alterations but not dyslipidemia and insulin resistance in central bearded dragons (Pogona vitticeps)

“…11 Decreasing β-oxidation of fatty acids was proposed as a plausible mechanism to explain this finding in chickens as suggested in this study. Because BHBA concentrations also increase with fasting in sauropsids, 23,24 it should ideally be measured after standardized fasting, especially for monitoring purposes. AJVR Succinic acid was initially found to be an important biomarker for hepatic lipid accumulation in bearded dragons in a previous metabolomics pilot study, 8 but this was not confirmed in this larger study, invalidating parts of our initial research hypothesis.…”

Varying intensities of chronic stress induce inconsistent responses in weight and plasma metabolites in house sparrows (Passer domesticus)

“…Although glucose is tightly regulated in birds ( Alonso-Alvarez & Ferrer, 2001 ; Basile et al, 2021 ; Castellini & Rea, 1992 ; Rodríguez, Tortosa & Villafuerte, 2005 ), one primary effect of corticosterone during acute stress is to raise plasma glucose levels ( Davies et al, 2013 ; Deviche et al, 2016b ) (but see Deviche et al, 2016a , 2014 ; Fokidis et al, 2011 ), potentially to aid in the recovery of the stressor or to prepare for the next stressor ( Munck & Koritz, 1962 ; Romero & Wingfield, 2016 ). Ketones spike in the bloodstream when fat deposits are broken down, and can be used as an indication of fasting ( Berg, Tymoczko & Stryer, 2002 ; Buyse & Decuypere, 2015 ; Cherel et al, 1988 ; Totzke et al, 1999 ), short-term mass change ( Cerasale & Guglielmo, 2006 ), and as proxy for performance ( Kaliński et al, 2022 ; Lindholm, Altimiras & Lees, 2018 ). Corticosterone can increase plasma ketones as a result of gluconeogenesis during chronic stress ( Bernard et al, 2002 ; Viblanc et al, 2018 ).…”