Factors affecting leucocyte profiles in the little auk, a small Arctic seabird

Abstract

Leucocyte profiles, especially the heterophil/ lymphocyte ratio (H/L), are widely used to assess immune function and stress in birds. In this study, we investigated whether leucocyte profiles in a small colonial seabird, the little auk (Alle alle), are related to age (chicks, adults), sex or biometric traits, including body mass. We blood-sampled chicks at 4-8 and 14-18 days of life and chick-feeding adults with 14-20-and 24-30-day-old chicks. Relative numbers of heterophils and H/L generally differed among chicks and adults, with the highest values in adults with 14-20-day-old chicks and the lowest ones in 4-8-day-old chicks. Females had a higher proportion of lymphocytes than males. The relative numbers of eosinophils were similar in all the groups. The percentage of monocytes tended to differ among the age categories. Analyses of chicks revealed that the percentage of heterophils and the H/L ratios were significantly higher in older than in younger chicks. The opposite pattern was recorded for lymphocytes. In 14-18-day-old chicks, H/L (stress level) was negatively related to body mass, head-bill length and bill width. This time period is energetically stressful as nestlings start to exercise their wings outside the nest chamber. This suggests that the origin of stress in nestlings was mainly nutritional. We found a significant positive correlation between body mass at fledging and the relative number of eosinophils at 14-18 days of life, indicating a higher level of stress in lighter nestlings. The significant relationship between fledging age and the percentage of monocytes at 14-18 days of life suggested a poorer state of health in chicks that fledged at an older age.

Leukocyte profiles indicate nutritional, but not moulting stress in a migratory shorebird, the Common Snipe (Gallinago gallinago)

“…Although we are aware of no previous research that examined relationships between plasma metabolite concentrations and H/L ratios in migrating birds, many studies have reported elevated H/L ratios in individuals with low body mass or experiencing food deprivation (Ots et al 2001;Gladbach et al 2010;Krams et al 2011;Jakubas et al 2015; but see Krams et al 2012). For example, male Upland Geese (Chloephaga picta leucoptera) showed negative correlation Table 1 Means ± standard error (SE) for condition indices and ratio of heterophils to lymphocytes (H/L ratio) in young (n = 282) and adult (n = 91) Common Snipe migrating through central Poland Because of the log-normal distribution, geometric mean ± SE is shown for the H/L ratio.…”

Breeding phased dependent oxidative balance in a small High Arctic seabird, the little auk

“…It has also been reported for fish that production of ROS by phagocytic leukocytes is stimulated by prolactin (Yada et al 2001, Olavarría et al 2010. Given a five-fold higher level of prolactin during incubation compared to chick-rearing reported in the little auk (Wojczulanis- Jakubas et al 2015), this hormone may be responsible for stimulation of immune system during incubation, which in turns is reflected in higher OS and ROMs levels ( Fig. 1A-B).…”

Immune configuration in hatchling snakes is affected by incubation moisture, and is linked to subsequent growth and survival in the field

“…We infer that snakes with higher growth, and a higher probability of recapture, are likely to have higher lifetime reproductive success ( = fitness, in evolutionary terms). To our knowledge, these are the first data to demonstrate empirical links between WBC counts and individual variation in life‐history traits in reptiles, though studies on birds have reported correlations between leuckocyte profiles of nestlings and fitness traits (Dehnhard et al., ; Jakubas, Wojczulanis‐Jakubas, & Kośmicka, ; Masello et al., ). Nonetheless, the causal basis of such links remains ambiguous.…”