Assessing Passeriformes health in South Texas via select venous analytes

Flexibility underlies differences in mitochondrial respiratory performance between migratory and non-migratory White-crowned Sparrows (Zonotrichia leucophrys)

Migration is one of the most energy-demanding behaviors observed in birds. Mitochondria are the primary source of energy used to support these long-distance movements, yet how mitochondria meet the energetic demands of migration is scarcely studied. We quantified changes in mitochondrial respiratory performance in the White-crowned Sparrow (Zonotrichia leucophrys), which has a migratory and non-migratory subspecies. We hypothesized that the long-distance migratory Gambel's subspecies (Z. l. gambelii) would show higher mitochondrial respiratory performance compared to the non-migratory Nuttall's subspecies (Z. l. nuttalli). We sampled Gambel's individuals during spring pre-migration, active fall migration, and a period with no migration or breeding (winter). We sampled Nuttall's individuals during periods coinciding with fall migration and the winter period of Gambel's annual cycle. Overall, Gambel's individuals had higher citrate synthase, a proxy for mitochondrial volume, than Nuttall's individuals. This was most pronounced prior to and during migration. We found that both OXPHOS capacity (state 3) and basal respiration (state 4) of mitochondria exhibit high seasonal flexibility within Gambel's individuals, with values highest during active migration. These values in Nuttall's individuals were most similar to Gambel's individuals in winter. Our observations indicate that seasonal changes in mitochondrial respiration play a vital role in migration energetics.

Revisiting glucose regulation in birds - A negative model of diabetes complications

Birds naturally have blood glucose concentrations that are nearly double levels measured for mammals of similar body size and studies have shown that birds are resistant to insulin-mediated glucose uptake into tissues. While a combination of high blood glucose and insulin resistance is associated with diabetes-related pathologies in mammals, birds do not develop such complications. Moreover, studies have shown that birds are resistant to oxidative stress and protein glycation and in fact, live longer than similar-sized mammals. This review seeks to explore how birds regulate blood glucose as well as various theories that might explain their apparent resistance to insulin-mediated glucose uptake and adaptations that enable them to thrive in a state of relative hyperglycemia.

Tissue distribution and sublethal effects of imidacloprid in the South American grayish baywing (Agelaioides badius)

The neonicotinoids are globally used insecticides, which have been shown to cause negative impacts on birds. The current study aimed to evaluate the distribution of the neonicotinoid imidacloprid (IMI) in the tissues of a songbird and identify related physiological effects. Adults of the grayish baywing (Agelaioides baduis) were administered with a single dose of 35 mg IMI/kg, and the IMI concentration was evaluated in liver, kidney and plasma at 4, 12, 24, and 48 h after dosing. At the same time points, effects on hematological, genetic and enzymatic parameters were assessed. Results showed that IMI was absorbed before 4 h, and eliminated at 48 h, in every tissue, and the highest concentrations were detected in plasma. Baywings showed intoxication signs and reduced mobility within the first 5 min post-dosing. Hematological parameters: red blood cells, packed cell volume, hemoglobin, and their derived indices exhibited a transient elevation 24 h after dosing, which coincided with maximum concentrations of IMI in the tissues. No effects were observed on the genotoxicity parameters evaluated: micronuclei and comet assay. Treated birds exhibited an alteration of cholinesterases activity in the muscle and plasma, and of glutathione-S-transferase (GST) activity in the plasma, brain, liver, and muscle. Based on the results obtained, the combined detection of IMI and inhibition of GST activity in the plasma is suggested as a non-lethal biomarker of IMI exposure in wild birds. As efficient field monitoring depends on the availability of proven biomarkers, the current study provides valuable tools for bird conservation in agroecosystems.

Venous Blood Analytes and Osmolality of Rehabilitated Juvenile Black-bellied Whistling Ducks (Dendrocygna autumnalis)

Venous blood samples were collected from 129 apparently healthy, rehabilitated juvenile black-bellied whistling ducks (Dendrocygna autumnalis) immediately before release from rehabilitation. Blood gas, electrolyte, and select biochemical and hematologic values were analyzed by using a point-of-care analyzer, and complete blood cell counts and osmolality were determined. Most biochemical analyte values were distributed parametrically, while most hematologic values were nonparametrically distributed. Calculated osmolality values were in poor agreement with measured osmolality values, and values of packed cell volume had poor agreement with hematocrit values determined with the i-STAT 1. The physiologic values reported provide vital information to assess individual duck health and guide fluid therapy in captivity and may prove useful to assess free-living population health of this duck species.