Kenneth A Schmidt

Kenneth A Schmidt
Texas Tech University | TTU · Department of Biological Sciences

PhD; Ecology and Evolution

About

91
Publications
14,734
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5,804
Citations
Additional affiliations
January 2000 - present
Cary Institute of Ecosystem Studies
Position
  • Visting Scientist

Publications

Publications (91)
Article
Full-text available
Information is characterized as the reduction of uncertainty and by a change in the state of a receiving organism. Thus, organisms can acquire information about their environment that reduces uncertainty and increases their likelihood of choosing a best-matching strategy. We define the ecology of information as the study of how organisms acquire an...
Article
1. Territory choice is likely to include sequential sampling at prospective sites, a decision rule for accepting a site, and, when available, use of prior experience. Here I consider the threshold rule (Real 1990) in which individuals choose the first option that exceeds a preset level of quality, and ask how competition for sites limits the choosi...
Article
Full-text available
Social information is used widely in breeding habitat se- lection and provides an efficient means for individuals to select hab- itat, but the population-level consequences of this process are not well explored. At low population densities, efficiencies may be reduced be- cause there are insufficient information providers to cue high-quality habita...
Article
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The choice of breeding territory can strongly affect an individual's fitness. Individuals can use information obtained from social cues emitted by other organisms to assess territory quality when making settlement decisions. Social information sourced from cues indicating the current inhabitants' reproductive success (i.e., performance-based cues)...
Article
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Despite the wide usage of the term information in evolutionary ecology, there is no general treatise between fitness (i.e. density‐dependent population growth) and selection of the environment sensu lato. Here we 1) initiate the building of a quantitative framework with which to examine the relationship between information use in spatially heteroge...
Article
1. Global climate change impacts species and ecosystems in potentially harmful ways. For migratory bird species, earlier spring warm-up could lead to a mis-match between nesting activities and food availability. CO 2 provides a useful proxy for temperature and an environmental indicator of climate change when temperature data are not available for...
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Shannon’s information (H) has two meanings: information and surprise (Shannon’s original term.) This terminology characterizes the dual nature of H: 1) a reduction in uncertainty, and 2) heterogeneity, the enabler of surprise, for there is no information in a heterogeneity continuously homogeneous world. Embracing the dual nature of information/het...
Article
Information use constitutes the key aspect of phenotype–environment interactions for any organism living in a heterogeneous environment, as information increases the chances of making the decisions that match the current perceived state of the world. Information use is ubiquitous in a variety of contexts and organisms throughout their lifetime are...
Article
Breeding nest site selection is often the first defense against nest predation risk. To be effective, this mechanism requires site‐specific spatial heterogeneity in predator abundance which produces predator‐poor space, prey's ability to assess spatial heterogeneity in risk, and few or weak constraints on the ability to settle in within predator‐po...
Article
Full-text available
Summary 1. Territory choice is likely to include sequential sampling at prospective sites, a decision rule for accepting a site, and, when available, use of prior experience. Here, I consider the threshold rule (Real 1990 American Naturalist, 138, 901–917) in which individuals choose the first option that exceeds a preset level of quality and ask h...
Article
At the nest guild level, nest predation is a major cause of failure for many passerines. Species differ in behaviors that influence nest predation risk, presenting a challenge to nest survival analyses at the nest guild level. At our study site in southeastern New York, previous findings have suggested rodent nest predator abundance strongly drives...
Article
The combination of spatial structure and non-linear population dynamics can promote the persistence of coupled populations, even when the average population growth rate of the patches seen in isolation would predict otherwise. This phenomenon has generally been conceptualized and investigated through the movement of individuals among patches that e...
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Human-induced rapid environmental change, such as the introduction of exotic species, can create novel species interactions that might be detrimental to native organisms. For birds, introduced plant species may represent potentially attractive, but dangerous, locations to place a nest. If the environmental cues that birds use to select safe nest si...
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Nest predation is a key source of selection for birds that has attracted increasing attention from ornithologists. The inclusion of new concepts applicable to nest predation that stem from social information, eavesdropping or physiology has expanded our knowledge considerably. Recent methodological advancements now allow focus on all three players...
Article
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Avian vocalizations are common examples of the complex signals used by animals to negotiate during agonistic interactions. In this study, we used two playback experiments to identify agonistic signals in a songbird species with several acoustically complex songs and calls, the veery. In the first experiment, we compared veery singing behavior in re...
Article
The role of temporal changes and spatial variability in predation risk and prey's means of mitigating such risks is poorly understood in the context of potential threats of global climate change for migratory birds. Yet nest predation, for example, represents a primary source of reproductive mortality in birds. To assess risk birds must spend time...
Article
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Humans in the northeastern and midwestern United States are at increasing risk of acquiring tickborne diseases - not only Lyme disease, but also two emerging diseases, human granulocytic anaplasmosis and human babesiosis. Co-infection with two or more of these pathogens can increase the severity of health impacts. The risk of co-infection is intens...
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Anaplasmosis is an emerging infectious disease caused by infection with the bacterium Anaplasma phagocytophilum. In the eastern United States, A. phagocytophilum is transmitted to hosts through the bite of the blacklegged tick, Ixodes scapularis. We determined the realized reservoir competence of 14 species of common vertebrate hosts for ticks by e...
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Predation is an important cost of communication in animals and thus a potent selection pressure on the evolution of signaling behavior. Heterospecific eavesdropping by predators may increase the vulnerability of vocalizing prey, particularly during low light, such as at dusk when nocturnal predators are actively hunting. Despite the risk it entails...
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Fourteen vertebrate species (10 mammals and 4 birds) were assessed for their ability to transmit Anaplasma phagocytophilum, the bacterium that causes human granulocytic anaplasmosis, to uninfected feeding ixodid ticks. Small mammals were most likely to infect ticks but all species assessed were capable of transmitting the bacterium, in contrast to...
Conference Paper
Background/Question/Methods For migratory songbirds, the term territory is usually defined as the area an individual or breeding pair defends against conspecifics, while home range refers to the total area that an individual uses, but does not defend, during the breeding season. Since one of the primary functions of passerine song is territory def...
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We compared the amount and type of acoustic competition experienced by Veeries (Catharus fuscescens) when they sang in the dawn chorus as opposed to when they sang in the dusk chorus. Veery songs tended to be masked more often at dawn than at dusk. Veery songs were masked 2.4 times per 10-song sequence at dawn and 1.2 times per 10-song sequence at...
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A resource's susceptibility to predation may be influenced by its own palatability and the palatability of its neighbors. We tested for effects of plant chemical defenses on seed survival by manipulating the frequency of palatable and less palatable sunflower seeds in food patches subject to harvest by fox squirrels (Sciurus niger) and gray squirre...
Conference Paper
Background/Question/Methods Density dependence in populations can be produced through a simple mechanism of heterogeneity in site (i.e., territory) quality where individuals fill up available sites in rank order of quality (site dependent regulation). This concept implicitly assumes that individuals are perfectly informed with regard to territory...
Conference Paper
Full-text available
Background/Question/Methods Predation is an important ecological cost of communication in animals and is thus a potent source of selection on signaling behavior. Heterospecific eavesdropping by predators may increase the vulnerability of actively vocalizing prey, particularly at dusk when nocturnal predators are hunting while songbirds are singin...
Article
1. Information benefits organisms living in a heterogeneous world by reducing uncertainty associated with decision making. For breeding passerines, information reliably associated with nest failure, such as predator activity, can be used to adjust breeding decisions leading to higher reproductive success. 2. Predator vocalizations may provide a sou...
Article
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Acquiring information regarding resource patchiness can reduce uncertainty in foraging decisions. However, information on patch quality may come at a cost if, when foraging within a risky (micro)environment, foragers allocate more attention to predator detection and consequently allocate less attention to assessing resource patchiness, that is, the...
Article
Seasonal fecundity is strongly influenced by the number of nests attempted (including renests following nest failure) in a season. This number is often assumed to be set by the length of the breeding season or through some predetermined maximum. Instead, the decision to renest likely results from a cost–benefit analysis honed by natural selection w...
Article
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Vectors of infectious diseases are generally thought to be regulated by abiotic conditions such as climate or the availability of specific hosts or habitats. In this study we tested whether blacklegged ticks, the vectors of Lyme disease, granulocytic anaplasmosis and babesiosis can be regulated by the species of vertebrate hosts on which they oblig...
Conference Paper
Background/Question/Methods Human granulocytic anaplasmosis (HGA) is an emerging tick-borne disease in North America, Europe, and Asia. Patients with HGA suffer flu-like symptoms that can be acute, and approximately 1-4% of patients die, though many less severe cases probably go unreported. HGA is caused by infection with a rickettsial bacterium,...
Conference Paper
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Background/Question/Methods The probability that any given host will be exposed to a vector-borne pathogen increases with increasing population density of the vector and with increasing proportion of vectors that are infected. Vector density and infection prevalence, however, might be affected by different ecological factors. For vectors with ine...
Article
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The drivers of variable disease risk in complex multi-host disease systems have proved very difficult to identify. Here we test a model that explains the entomological risk of Lyme disease (LD) in terms of host community composition. The model was parameterized in a continuous forest tract at the Cary Institute of Ecosystem Studies (formerly the In...
Article
1. Synchronized mass production of seed crops, such as acorns, produces a resource pulse that may have far-reaching consequences for songbird populations through its effects on avian predators. Seed production in these forests represents only the first of several pulsed events. Secondary pulses emerge as mast-consuming rodents numerically respond t...
Article
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Vocally signaling a predator's presence through alarm calls creates public information regarding risk in the environment. If having this information confers an advantage, eavesdropping behavior, the use of information in signals by individuals other than the primary target, is expected to evolve. Thus, eavesdropping for information on predation ris...
Article
Some of the clearest examples of the ramifying effects of resource pulses exist in deciduous forests dominated by mast-producing trees, such as oaks, beech, and hornbeam. Seed production in these forests represents only the first of several pulsed events. Secondary pulses emerge as mast-consuming small rodents numerically respond to seed production...
Article
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Caching behavior frequently occurs within a social context that may include heterospecific cache pilferers. All else equal, the value of cacheable food should decline as the probability of cache recovering declines. We manipulated gray squirrels' (Sciurus carolinensis) estimate of the probability of cache recovery using experimental playbacks of th...
Article
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Predation has major impacts on survival and reproductive success for many species. To quantify these effects, ecologists often choose to intensively study prey populations to measure predation rates and/or estimate predator abundance. But in some cases, predation rates are less strongly related to predator abundance per se than to spatial and tempo...
Article
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The ability of prey to find and use predator-free space has far-reaching consequences for their persistence and interactions with their predators. We tested whether nest survivorship of the ground-nesting veery (Catharus fuscescens) and shrub-nesting wood thrush (Hylocichla mustelina) was related to the local absence of a major nest predator, the w...
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Non-lethal effects of predators on prey are initiated in the form of responses to direct and indirect cues of predation risk. Like their lethal equivalents, non-lethal effects may affect species further down the food web initiating a behaviorally-driven trophic cascade. I presented a direct cue of predation risk, owl vocalizations, to white-footed...
Conference Paper
A plant's susceptibility to herbivory may be influenced by its own palatability and the palatability of its neighbors. We tested for effects of plant chemical defenses on seed survival by manipulating the frequency of control and oxalate-treated sunflower seeds in food patches subject to seed harvest by free-living fox squirrels (Sciurus niger). We...
Article
Previous studies have demonstrated that songbirds often use exotic plants as nesting substrates and may suffer elevated predation rates relative to nests placed in native plants. Veeries (Catharus fuscescens) frequently build nests in an exotic shrub, Japanese barberry (Berberis thunbergii), in forests of southeastern New York State, USA. We monito...
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Male Wood Thrushes (Hylocichla mus-telina) attend their nests by perching near its rim, a behavior common to many species and presumed to be for the purpose of guarding eggs or young in the nest. We classified nests into two groups based on whether or not we observed an attending male during any nest inspection. We found that nests attended by male...
Article
We derived unique sets of predictions from patch use theory to differentiate apparent, exploitative and interference competition. Armed with these predictions, we used field enclosures to determine whether white-footed mice (Peromyscus leucopus) perceived meadow voles (Microtus pennsylvanicus) as apparent competitors. The enclosures were sited at f...
Article
Full-text available
Male Wood Thrushes (Hylocichla mustelina) attend their nests by perching near its rim, a behavior common to many species and presumed to be for the purpose of guarding eggs or young in the nest. We classified nests into two groups based on whether or not we observed an attending male during any nest inspection. We found that nests attended by male...
Article
Many communities consist of a generalist predator that consumes multiple prey species whose persistence is thereby threatened through the indirect effect of apparent competition. However, uncommon and/or ephemeral prey may be encountered only incidentally through the predator's effort expended to consume primary prey. In such instances, the functio...
Article
Site fidelity, the phenomenon of remaining faithful to sites, often where an individual has bred successfully in the past, has important consequences for population dynamics. Previous results have shown that site fidelity results in a positive correlation between population density and fitness. Here, I build on this theme by incorporating site fide...
Article
Many terrestrial ecosystems are characterized by intermittent production of abundant resources for consumers, termed pulsed resources. The impact of resource pulses on populations downwind of the initial pulse are only beginning to be characterized, while the relationship between the frequencies of pulses and the long-term growth rate of affected s...
Article
The density-dependence inherent in population interactions can be under-mined when the behavior or distribution of predators is not predictable from their population density. For instance, unequal use of space by consumers can lead to improper character-izations of their interaction with prey if based solely on population density. Instead, quitting...
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The extent to which the biodiversity and community composition of ecosystems affect their functions is an issue that grows ever more compelling as human impacts on ecosystems increase. We present evidence that supports a novel function of vertebrate biodiversity, the buffering of human risk of exposure to Lyme-disease-bearing ticks. We tested the D...
Article
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In response to mast production of acorns, populations of small mammals, such as the white-footed mouse and eastern chipmunk, greatly increase and, in turn, initiate cascades of direct and indirect effects that permeate throughout forest communities. To examine the strength of the effects stemming from acorn crops, we conducted studies in oak-domina...
Article
Individuals, free to choose between different habitat patches, should settle among them such that fitness is equalized. Alternatives to this ideal free distribution result into fitness differences among the patches. The concordance between fitnesses and foraging costs among inhabitants of different quality patches, demonstrated in recent studies, s...
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We examined the effects of separate removal experiments of two generalist consumers, the white-footed mouse (Peromyscus leucopus) and the eastern chipmunk (Tam- ias striatus), on nest predation rates of forest songbirds. Mice are numerically dominant at our study sites and were shown to be strong predators in other predator-prey interactions, such...
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Incidental predation occurs when secondary prey items are encountered and subsequently consumed, not through directed search for such prey, but through their con- sequential encounter by a predator engaged in search for primary prey. We developed a mathematical model that examines the relationships between the abundance of primary prey, patch explo...
Article
The phenomenon of site fidelity (i.e. remaining faithful to sites where an individual has bred successfully in the past) has been documented for many taxa, especially birds. It has been suggested that individuals may use a simple rule of thumb: stay (or return) if breeding was successful, or switch to a new site if breeding was unsuccessful (win-st...
Article
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Many infectious diseases of humans are caused by pathogens that reside in nonhuman animal reservoirs and are transmitted to humans via the bite of an arthropod vector. Most vectors feed from a variety of host species that differ dramatically in their reservoir competence; that is, their probability of transmitting the infection from host to vector....
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Small rodents such as the white-footed mouse (Peromyscus leucopus) and the eastern chipmunk (Tamias striatus) efficiently transmit Borrelia burgdorferi, the etiologic agent of Lyme disease, to feeding ticks, whereas other hosts of ticks are less efficient reservoirs of B. burgdorferi. We examined the roles of ground-foraging and ground-nesting song...
Article
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We develop mathematical and graphical models of diet selection incorporating recent advances in digestive physiology - that is, the adaptive modulation of active nutrient transport and gut retention time in response to changes in diet composition - into an explicitly ecological context based on consumer-resource dynamics and optimal foraging theory...
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We investigate how coexistence between competitors may be influenced by habitat selection when habitats represent either sources or sinks, and given that dispersal is free to evolve. Evolutionary stable dispersal between source and sink habitats can occur if local fitnesses vary temporally, either due to intrinsic factors (e.g., chaotic dynamics) o...
Article
The role of plant defensive compounds has often been studied within the purview of consumer diet choice. However, consumers are often confronted with foods distributed within depletable patches. To investigate the complication of resource depletion, I merged a consumer-resource model of nutritional relationships between foods with the technique of...
Article
Small rodents such as the white-footed mouse (Peromyscus leucopus) and the eastern chipmunk (Tamias striatus) efficiently transmit Borrelia burgdorferi, the etiologic agent of Lyme disease, to feeding ticks, whereas other hosts of ticks are less efficient reservoirs of B. burgdorferi. We examined the roles of ground-foraging and ground-nesting song...
Article
Full-text available
The risk of humans acquiring Lyme disease is a function of the local density of nymphal and adult ticks that are infected with Lyme disease spirochetes. This in turn, will be related to host-use patterns of ticks and to the densities of both juvenile ticks and their hosts. At a forested site in Dutchess County, NY, we quantified host-use patterns o...
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Habitat fragmentation and disturbance exacerbate the invasion of exotic plant species that, in turn, may attract nesting songbirds by providing a branch structure suitable for nest sites. We document that American Robin (Turdus migratorius) nests in two exotic plants, Lonicera maackii and Rhamnus cathartica, experienced higher predation than nests...
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In their recent article, Wilson and Cooper (1998) reported that Acadian Flycatchers (Empidonax virescens) selected nest trees nonrandomly, but that their choice of nest tree did not influence nest success. They concluded that nest predation appears random in time and space. However, we show their metric for nest tree use (% use - % available) is a...
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Nest predation, if density dependent, may structure avian communities by selecting for nest-site characteristics that dilute the predators' perception of nest density (e.g., by increasing the number and types of potential nest sites) thereby reducing losses to predators. We tested for density dependent nest predation at a site dominated by predatio...
Article
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Nest predation studies have typically documented patterns related to habitat characteristics rather than investigate predation as an interaction between predator and prey. In contrast, this article presents a simple model that seeks an explanation for variation in nest predation rates through an application of foraging theory. Changes in the enviro...
Article
The impacts of nest predation and brood parasitism on the seasonal fecundity of birds are strongly dependent on the number of nesting attempts, and thus seasonal fecundity is responsive to behavioral traits that increase the number of opportunities to nest. We developed simple models to investigate the relative impacts of nest predation and brood p...
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Apparent competition (i.e., a mutually negative indirect interaction between prey species through shared predation) arises when predator abundance or foraging effort increases with total prey availability. We review and formalize several patch-use models from which we derive predictions for how the degree of coupling (from the predators' perspectiv...