Julie A Heath

Boise State University | BSU · Department of Biological Sciences

Natural variation in migratory strategies across the range of the American Kestrel (Falco sparverius) creates a unique opportunity for comparative research of annual cycles. However, it can be logistically and technically challenging to track such a small but highly mobile species. We tagged American Kestrels with light-level geolocators or satelli...

Seasonal migration is a dynamic natural phenomenon that allows organisms to exploit favourable habitats across the annual cycle. While the morphological, physiological and behavioural changes associated with migratory behaviour are well characterized, the genetic basis of migration and its link to endogenous biological time-keeping pathways are poo...

Birds aim to optimize resources for feeding young and self-maintenance by timing reproduction to coincide with peak food availability. When reproduction is mistimed, birds could incur costs that affect their survival. We studied whether nesting phenology correlated with the apparent survival of American kestrels (Falco sparverius) from two distinct...

Optimal reproductive performance occurs when birds time reproduction to coincide with peak food availability. Deviation from optimal timing, or mismatch, can affect productivity, though birds may mediate some mismatch effects by altering their incubation behavior. We studied the consequences of nesting timing (i.e., clutch initiation relative to an...

Climate-driven advances in spring can result in phenological mismatch between brood rearing and prey availability and consequently cause decreased productivity in birds. How consequences of mismatch vary across species’ ranges, and how individual behavior can mitigate mismatch effects is less studied. We quantified the relationship between phenolog...

To conserve biological diversity in a changing world, managers must understand which species are vulnerable to the effects of climate change and whether there is sufficient capacity for these species to adapt. This is especially applicable to birds, who may experience changes in phenology (e.g., the timing of migration and/or breeding) in response...

Most raptor populations are declining and nearly a fifth are threatened with extinction; thus there is a need to increase collaboration to ensure efficient and effective research, management, and conservation. Here, we introduce the Global Raptor Impact Network (GRIN; www.globalraptors.org), a tool to enhance collaboration and conservation impact o...

Over the past 50 years conservation genetics has developed a substantive toolbox to inform species management. One of the most long-standing tools available to manage genetics - the pedigree - has been widely used to characterize diversity and maximize evolutionary potential in threatened populations. Now, with the ability to use high throughput se...

Over the past 50 years conservation genetics has developed a substantive toolbox to inform species management. One of the most long‐standing tools available to manage genetics ‐ the pedigree ‐ has been widely used to characterize diversity and maximize evolutionary potential in threatened populations. Now, with the ability to use high throughput se...

Haematophagous ectoparasites can directly affect the health of young animals by depleting blood volume and reducing energetic resources available for growth and development. Less is known about the effects of ectoparasitism on stress physiology (i.e. glucocorticoid hormones) or animal behaviour. Mexican chicken bugs (Haematosiphon inodorus; Hemipte...

Wildfires and invasive species have caused widespread changes in western North America’s shrub-steppe landscapes. The bottom–up consequences of degraded shrublands on predator ecology and demography remain poorly understood. We used a before–after paired design to study whether Golden Eagle (Aquila chrysaetos) diet and nestling survivorship changed...

Over the past 50 years conservation genetics has developed a substantive toolbox to inform species management. One of the most long-standing tools available to manage genetics-the pedigree-has been widely used to characterize diversity and maximize evolutionary potential in threatened populations. Now, with the ability to use high throughput sequen...

Identifying population genetic structure is useful for inferring evolutionary process and comparing the resulting structure with subspecies boundaries can aid in species management. The American Kestrel (Falco sparverius) is a widespread and highly diverse species with 17 total subspecies, only 2 of which are found north of U.S./Mexico border (F. s...

In migratory birds, among‐ and within‐species heterogeneity in response to climate change may be attributed to differences in migration distance and environmental cues that affect timing of arrival at breeding grounds. We used eBird observations and a within‐species comparative approach to examine whether migration distance (with latitude as a prox...

While outdoor recreationists often report increases to their well-being for time spent in nature, the mechanisms through which local ecologies affect human health have been difficult to quantify, and thus to manage. We combine data from pre-post salivary cortisol measures, GPS tracks, visitor photos, and surveys from 88 hikers traversing several ty...

Demographic differences between stable and declining populations can lend insight into drivers of population decline. The American Kestrel (Falco sparverius) is a widespread and often‐studied falcon, yet its demography is poorly understood and causes of observed population declines across much of North America remain unknown. Using integrated popul...

Illegal killing of nongame wildlife is a global yet poorly documented problem. The prevalence and ecological consequences of illegal killing are often underestimated or completely unknown. We review the practice of legal recreational shooting and present data gathered from telemetry, surveys, and observations on its association with illegal killing...

Telomere length dynamics are an established biomarker of health and aging in animals. The study of telomeres in numerous species has been facilitated by methods to measure telomere length by real‐time quantitative PCR (qPCR). In this method, telomere length is determined by quantifying the amount of telomeric DNA repeats in a sample and normalizing...

Dispersal is a critical process influencing population dynamics and responses to global change. Long‐distance dispersal (LDD) can be especially important for gene flow and adaptability, although little is known about the factors influencing LDD because studying large‐scale movements is challenging and LDD tends to be observed less frequently than s...

Supplementary food resources (e.g., subsidies) associated with agriculture can benefit wildlife species, increasing predictability and availability of food. Avian scavengers including raptors often utilize subsidies associated with both recreational hunting and pest shooting on agricultural lands. However, these subsidies can contain lead (Pb) frag...

There is widespread evidence that species distributions are shifting in response to climate change. Warming temperatures and climate niche constraints are hypothesized drivers of northward shifts in temperate migratory bird breeding distributions, but heterogeneity in the direction of distribution shifts suggests that the climate niche hypothesis d...

The role of telomere dynamics in health and aging has been facilitated by the development of qPCR-based telomere length measurements. However, the widespread application of this approach has been limited because of the challenge of developing appropriate reference primers in non-model organisms with genomes that have not been sequenced. Here we dev...

Understanding human use of landscapes is important for managing recreational lands. Predicting human behavior is difficult, however, and methods for assessing human habitat use could benefit from advances in other fields. Habitat selection methods from wildlife ecology provide useful tools for studying such topics. We present a case study of the ad...

Studies of cliff-nesting raptors can be challenging because direct observations of nest contents are difficult. Our goals were to develop a protocol for installing motion-activated trail cameras at Golden Eagle (Aquila chrysaetos) nests to record diet information and productivity, and to estimate prey detection probability using different diet stud...

As nature-based recreation grows in popularity, there is concern for reduced fitness of animals exposed to chronic disturbance by these activities. Golden Eagles (Aquila chrysaetos) and other raptors are sensitive to human recreation near their nests, and managers of these species need strategies to mitigate negative effects. We used simulation mod...

Avian trichomonosis, caused by the protozoan Trichomonas gallinae, affects bird-eating raptors worldwide. Raptors can develop trichomonosis by feeding on infected prey, particularly Rock Pigeons (C olumba livia), which are a reservoir for T. gallinae. Raptors may be particularly vulnerable to T. gallinae infection in degraded habitats, where change...

Recreation on public lands is growing and is increasingly recognized as an ecosystem service providing improved health, connection to nature, and social time while also disturbing and degrading ecosystems. Human impacts must be managed, but often managers have little information about the factors that affect recreation patterns. We combined data fr...

Disturbance because of human activity, including recreation on wildlands, can affect bird behavior which in turn can reduce breeding success, an important consideration for species of management concern. We observed Golden Eagles (Aquila chrysaetos) during the breeding season to determine whether the probability of flushing was affected by the type...

Nest boxes are posted to provide breeding sites for cavity-nesting birds but less is known about their function in the nonbreeding season, when nest boxes may become important roost sites. In winter months, we surveyed 79 nest boxes before dawn for roosting American Kestrels (Falco sparverius) and other cavity-nesting birds in southwestern Idaho an...

An individual's investment in constitutive immune defenses depends on both intrinsic and extrinsic factors. We examined how Leucocytozoon parasite presence, body condition (scaled mass), heterophil-to-lymphocyte (H:L) ratio, sex, and age affected immune defenses in golden eagle (Aquila chrysaetos) nestlings from three regions: California, Oregon, a...

On the cover: The cover image, by Elisabeth MacColl et al., is based on the Research Article Correlates of immune defenses in golden eagle nestlings, DOI: 10.1002/jez.2081. Photo Credit: Ben Dudek.

Despite common use, the efficacy of artificial breeding sites (e.g., nest boxes, bat houses, artificial burrows) as tools for monitoring and managing animals depends on the demography of target populations and availability of natural sites. Yet, the conditions enabling artificial breeding sites to be useful or informative have yet to be articulated...

Annual counts of migrating raptors at fixed observation points are a widespread practice, and changes in numbers counted over time, adjusted for survey effort, are commonly used as indices of trends in population size. Unmodeled year-to-year variation in detectability may introduce bias, reduce precision of trend estimates, and reduce power to dete...

Warming temperatures cause temporal changes in growing seasons and prey abundance that drive earlier breeding by birds, especially dietary specialists within homogeneous habitat. Less is known about how generalists respond to climate-associated shifts in growing seasons or prey phenology, which may occur at different rates across land cover types....

There is widespread evidence that human disturbance affects wildlife behavior, but long-term population effects can be difficult to quantify. Individual-based models (IBMs) offer a way to assess population-level, aggregate effects of disturbance on wildlife. We created Tolerance in Raptors and the Associated Impacts of Leisure Sports (TRAILS), an I...

Different forms of outdoor recreation have different spatiotemporal activity patterns that may have interactive or cumulative effects on wildlife through human disturbance, physical habitat change, or both. In western North America, shrub-steppe habitats near urban areas are popular sites for motorized recreation and nonmotorized recreation and can...

Studies across annual cycles are important for understanding the consequences of carryover effects and predicting species’ responses to environmental change. Partially migratory populations, which consist of resident and migratory individuals, are excellent systems for studying how wintering strategies may affect reproduction. We examined whether w...

In wild birds, the proximate and ultimate factors that affect circulating carotenoid concentrations remain poorly understood. We studied variation in plasma carotenoid concentrations across several scales: annual, seasonal, pair, territory and individual, and evaluated whether plasma carotenoid concentrations explained reproductive outcome of wild...

Knowledge of habitat use by animals within urban-riparian corridors during the breeding season is important for conservation, yet remains understudied. We examined the bird community along an urban-riparian corridor through metropolitan Boise, Idaho and predicted that occupancy of individual species and species richness would be greater in forested...

There is widespread evidence that multiple drivers of global change, such as habitat degradation, invasive species, and climate change, are influencing wildlife. Understanding how these drivers interact with and affect species may be difficult because outcomes depend on the magnitude and duration of environmental change and the life history of the...

Climate change is having a dramatic effect on many migratory species. Changes in climate may lead to changes in food availability or other proximate cues that affect migratory behavior. We used 13 years (2000–2012) of data on songbird banding and raptor migration counts and captures during autumn migration in the intermountain West to evaluate whet...

Studies of multiple taxa across broad-scales suggest that species distributions are shifting poleward in response to global climate change. Recognizing the influence of distribution shifts on population indices will be an important part of interpreting trends within management units because current practice often assumes that changes in local popul...

Variation in recruitment patterns and dispersal behavior can have important consequences for population viability, genetic structure, and rates of evolutionary change. From 1992 to 2006 we studied a marked population of American Kestrels (Falco sparverius) nesting in boxes in southwestern Idaho to identify factors that affect local recruitment and...

The rapid increase of human activity in wild and developed areas presents novel challenges for wildlife. Some species may use human-dominated landscapes because of favourable resources (e.g. high prey availability along roadsides); however, use of these areas may increase exposure to anthropogenic stressors, such as human disturbance or noise, whic...

Habitat use has important consequences for avian reproductive success and survival. In coastal areas with recreational activity, human disturbance may limit use of otherwise suitable habitat. Snowy plovers Charadrius nivosus have a patchy breeding distribution along the coastal areas on the Florida Panhandle, USA. Our goal was to determine the rela...

Global climate change has affected avian migration patterns and nesting phenology. Changes in one phase of a bird's cycle will most likely affect other stages, but few studies focus simultaneously on multiple life-history events. We used western North American ringing records and Christmas Bird Counts to examine whether changes in migration pattern...

Size-adjusted mass is a common body condition index (BCI) used to indicate nonstructural energy reserves (fat and protein). BCIs are calculated from ratios of mass divided by a morphometric(s) or residuals of a regression between mass and a morphometric(s). The morphometrics used in BCIs must accurately represent structural size to reliably index e...

How nestling birds respond to stressful situations may constitute an important survival component that has lasting developmental effects on the hypothalamic pituitary adrenal (HPA) axis. As birds are exposed to increasing amounts of potential anthropogenic stressors through land use change, understanding how these factors contribute to HPA developm...

Coastal development and engineering projects preclude ecosystem processes that provide habitat for beach nesting birds. Management for coastal species may depend on actions that attempt to restore important habitat features and mitigate disturbance effects. However, species response to restoration or other management actions may be difficult to pre...

Low hatching success may limit progress towards reaching productivity goals for Atlantic Coast piping plover (Charadrius melodus) recovery, despite management strategies to protect eggs from predators and decrease human disturbance of birds on nests. We measured piping plover hatching success on Eastern Long Island beaches and identified the major...

Links between morphology and foraging strategies have been well established for many vertebrate groups. Foraging strategies of Melanerpes woodpeckers are especially variable, with at least six species being proficient flycatchers; the remainder of the better known species do not flycatch. Our objective was to examine variation in foraging tactics a...

We evaluated thirteen years (1995–2007) of Charadrius melodus (Piping Plover) nesting activity at Jones Beach State Park (JBSP) to examine temporal trends in the number of pairs, productivity, total young produced per year, and nest initiation. The number of plover pairs has decreased over time at JBSP, while productivity (and total number of young...

Nests, eggs, and chicks of nesting wading birds were unharmed by two fires in the Everglades. However, at least 50 adult White Ibises (Eudocimus albus) foraging away from the breeding colonies were killed during one fire. These results are counter-intuitive given that well-flighted adult birds seem more capable of escaping a fire than immobile nest...

Many hypotheses attempt to explain why younger, less experienced birds have a relatively low reproductive output. We evaluated reproductive patterns of marked American Kestrels Falco sparverius nesting in boxes in southwestern Idaho from 1992 to 2006 to test predictions of these hypotheses. Results were consistent with the selection (differential m...

Mercury, a common wetland pollutant, can affect wildlife populations through acute toxicity or through physiological effects that modify behavior and negatively influence reproductive success. We compared body-feather mercury concentrations of free-living male and female adult White Ibises (Eudocimus albus) during three breeding seasons in the Flor...

Many birds undergo bare part color changes during the breeding season. Most investigators have focused on color as a signal of individual quality. An alternative, but not exclusive, function of bare part color may be signaling readiness to breed, especially in colonial, asynchronous breeders. White Ibises (Eudocimus albus) are colonial waterbirds t...

Counts of nest starts are often used as indicators of the size of avian nesting populations, or of avian productivity. However, the accuracy of single or repeated counts of unmarked nests over time for estimating seasonal numbers of nests may be strongly affected by nest events that fall in between survey dates, or that occurred prior to or after t...

Mercury, a common wetland pollutant, can affect wildlife populations through acute toxicity or through physiological effects that modify behavior and negatively influence reproductive success. We compared body-feather mercury concentrations of free-living male and female adult White Ibises (Eudocimus albus) during three breeding seasons in the Flor...

During the late 1980s, the upper trophic-level biota of the Everglades (FL, USA) was recognized as being highly contaminated with mercury (Hg). However, the timing and pattern of that increase is poorly known, and no information is available about mercury contam ination in Everglades wildlife prior to 1974. We measured methylmercury concentrations...

We measured plasma concentrations of testosterone, estradiol, progesterone, and corticosterone; and recorded changes in gonad size, body condition, molt, and brood patch development of free-living adult White Ibises (Eudocimus albus) during the breeding season in the Florida Everglades. White Ibises are colonially breeding, long-legged wading birds...

The accuracy of aerial estimates of avian aggregation sizes is variable across studies, and the relative importance of techniques and inter-observer error to this variation are poorly understood. Using a scaled physical model of a wading bird colony, we examined accuracy and variation in observer counts of simulated large numbers (200–6000) of dens...

We lured White Ibises (Eudocimus albus) to trap sites with decoy plastic flamingos and captured them with a rocket net or mist nets. Our ability to attract ibises to a site (and consequently our capture success) was affected by vegetation height and water depth but not by decoy numbers or their arrangement. Both the rocket net (37 ibises) and mist...

Hydrogen stable isotope analysis of feathers is an important tool for estimating the natal or breeding latitudes of nearctic-neotropical migratory birds. This method is based on the latitudinal variation of hydrogen stable isotope ratios in precipitation in North America (deltaD(p)) and the inheritance of this variation in newly formed feathers (de...

We examined the adrenal response to handling stress of birds in different body conditions. In order to affect the birds' body condition, young (73-d old) female American kestrels (Falco sparverius) were maintained for 6 wk on one of three diets: a control diet (fed ad lib.) and two calorically restricted diets. To invoke a stress response, we remov...

We examined the adrenal response to handling stress of birds in different body conditions. In order to affect the birds' body condition, young (73‐d old) female American kestrels (Falco sparverius) were maintained for 6 wk on one of three diets: a control diet (fed ad lib.) and two calorically restricted diets. To invoke a stress response, we remov...

Many avian behavior patterns, such as breeding, migration and territoriality, are correlated with changes in hormone levels. Elevated levels of corticosterone, an adrenal steroid hormone, are associated with increased foraging and increased activity levels in birds. Young birds about to take their first Right may benefit from elevated plasma cortic...

Methods • We captured and banded American Kestrel adult and nestling (23-25 days old). • Collected 400 µl of blood from the jugular vein, blood was stored on ice until it could be processed in the lab. • Plasma and red blood cells were separated by centrifuging and plasma samples were stored at -80°C until carotenoid analysis. • 20 ul of plasma was...

Co-authored by Patricia Fontaine, Julie Heath and Greg Babbitt. "Research Work Order #188. Final report for the U.S. Army Corps of Engineers, Jacksonville, Office, P.O. Box 4970, Jacksonville, Florida." "31 March 1999." Includes bibliographical references (p. 54-59).

Thesis (M.S.)--Boise State University, 1996. Includes bibliographical references.

Breeding populations typically consist of a mix of locally-produced and immigrant birds. Recruitment of locally-produced birds depends on survival and dispersal patterns. American Kestrels breeding in boxes in Southwestern Idaho were marked and monitored from 1992-2006. Over the 14 years of our study, the proportion of locally produced American Kes...