Telomere Estimates by qPCR in American Kestrel Birds

Telomeres are highly conserved repeated sequences found at the ends of linear chromosomes. Measuring telomere length has been used to estimate the ages of individuals in several species. The research presented here focuses on developing telomere length estimates in the American Kestrel (Falco sparverius), using Quantitative Polymerase Chain Reaction (qPCR). The verification of a primer pair that can amplify a reference gene and serve to normalize the telomere qPCR data is vitally important. The gene for glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was preferably chosen because it occurs in a single copy in most birds. However, the Kestrel genome has not been sequenced making primer design challenging. We used a bioinformatics approach to find regions of the GAPDH gene that are conserved between chicken and several species of raptors. We also checked several published GAPDH primers reported in the literature. Here, we report the sequence and efficiency of qPCR primers that can be used for telomere length studies in the American Kestral

Degradation of Plant Secondary Metabolites in Green Nest Material Used by Golden Eagles

Golden Eagles (Aquila chrysaetos) have been observed lining their nests with green nesting material (GNM) that is known to have high levels of plant secondary metabolites (PSMs). The ‘nest protection hypothesis’ predicts that use of GNM containing cytotoxic PSMs deters infestation of parasites. Parasitic infestations can have critical consequences for nest occupants which may range from dehydration to nest abandonment. To better understand if GNM has an anti-parasite function, we observed the stability of PSMs (specifically terpenes and phenolics) from selected plant species found in nests under different exposure levels to sunlight in a simulated nest environment. GNM was analyzed every two days to determine the rate of degradation of PSMs. We predicted a decrease in PSMs over time with terpenes degrading more quickly than phenolics due to volatility. The rate of degradation of PSMs will influence the anti-parasitic activity of GNM and potentially how frequently eagles must collect fresh GNM

The Use of Hydrogen Stable Isotopes in Claws to Distinguish Between Migratory and Resident American Kestrels (Falco sparverius)

Partial migrant populations have individuals that migrate while others remain resident. American Kestrels (Falco sparverius) in southern Idaho are partial migrants. Individuals may migrate away from S. Idaho in winter, remain resident, or migrate south to winter in Idaho. Ratios of Hydrogen (H) and Deuterium (D) vary along a latitudinal gradient with values ranging from -140‰ near northern poles and 0‰ at the equator. We evaluated whether stable isotope ratios of H/D from keratin in claw tissue (δDc), which reflect the diet 3-4 months previous, could be used to distinguish between migratory and resident kestrels. We collected small claw samples in breeding and wintering seasons over three years. Claw samples were washed, weighed, pyrolyzed through gas chromatography and analyzed by a mass spectrometer. Preliminary results indicate that δDc of adult birds in spring are isotopically enriched compared to adults in winter. However, δDc of adult breeding birds is higher compared to nestling δDc, indicating a shift associated with age. This result is similar to shown δD in kestrel feathers. Results suggest that δDc of American Kestrels may be useful to identify migratory strategies

Investigating Deuterium Depletion in American Kestrel (Falco sparverius) Nestlings Using Growth Rates

Animal tissues should reflect the local precipitation isotope ratios of hydrogen (1H) and Deuterium (2H, or “D”) (δD). We found that nestling American Kestrels had relatively low δD values in their claws (δDc) compared to adults from the same area. Growth rates could possibly influence uptake of hydrogen isotopes during tissue development. To test this hypothesis, we examined the δDc of nestlings with different growth rates. We predicted that fast growing nestlings would show lower δDc due to increased uptake of 1H, while slow growing nestlings would show higher δDc. We collected small claw clipping samples and morphometrics from birds ranging from 21 to 25 days old. Claw samples were washed, weighed, pyrolyzed through gas chromatography and analyzed by mass spectrometer to obtain δDc. Results from this project will show if growth rates can explain the differences in δDc between adult and nestling American Kestrels

Effects of Bed Bugs: Do Golden Eagles Stress about Living with Hematophagous Parasites?

Ectoparasites can negatively affect their host with varying severity. The family Cimicidae, colloquially known as bed bugs, includes the obligate hematophagous Mexican chicken bug (Haematosiphon inodora). H. inodora populations have expanded north for 20 years and have been observed in Golden Eagle (Aquila chrysaetos) nests in Southern Idaho. Nestlings may be susceptible to effects of ectoparasites, like reduced body condition and mortality, because of their inability to evade the parasite. Exposure to H. inodora may elicit a stress response by the Hypothalamic–pituitary–adrenal (HPA) axis, increasing corticosterone (CORT) levels. We hypothesized that H. inodora in nests of Golden Eagles will reduce physiological condition and increase the HPA stress response of nestlings. We entered nests when nestlings were 4 and 7 weeks old, measured mass, collected blood, and noted the presence of ectoparasites. We evaluated physiological condition using hematocrit, body mass, and assayed plasma for CORT. Preliminary results suggest hematocrit and mass were significantly lower in nestlings with ectoparasites. This impaired physiological condition is likely to impact survival of Golden Eagles

Consequences of Timing: How Does Synchronization between Brood Rearing and Prey Availability Affect American Kestrel (Falco sparverius) Reproduction?

Previous studies have indicated that over the past 20 years winters have warmed, but spring temperatures remain unchanged in southwestern Idaho. During this time, American kestrels (Falco sparverius) have advanced their nesting period by 28 days. Changes in nesting phenology may result in early-breeding kestrels raising young before important peaks in prey availability occur, while later-breeding kestrels may have a greater likelihood in raising young during peak prey availability. We hypothesize that the degree of synchronization with prey availability affects kestrel reproduction and predict that nesting events synchronized with prey availability will produce young in better condition than asynchronous nests. We used morphological measurements of nestlings gathered since 2008 from a sample area containing ≈ 120 nest boxes to assess condition. We calculated a synchrony index for each nest based on the clutch initiation date and annual patterns of NDVI, a predictor of prey abundance. We then used the synchrony index to predict nestling growth. As climate change continues to intensify, it is crucial to learn how these changes impact the reproductive success of wildlife populations

Which is More Costly? The Effects of Migration vs. Overwintering on Telomeres of American Kestrels (Falco sparverius)

Little is known about the costs and benefits of different migration strategies. Telomeres are sequences at the end of chromosomes that prevent DNA degradation. Telomere length, and their ability to protect DNA, decreases with age and stress. We studied the telomere lengths of migrant and non-migrant American Kestrels to compare the relative stress and energetic demands of migration versus residency as wintering strategies. We captured nesting American Kestrels and classified migration strategy with hydrogen isotope analysis of claw samples. DNA was extracted from blood samples and telomere lengths were estimated by quantitative PCR (qPCR) using primers that bind to the telomeric repeat. This qPCR signal was normalized to the PCR signal from a single copy gene. Understanding the trade-offs between the costs of migration and overwintering is important for understanding the evolutionary ecology of migration and predicting how Kestrels may alter their wintering strategies in response to climate change