Alan Krakauer

University of California, Davis | UCD · Department of Evolution & Ecology

Evolutionary biologists have developed several indices, such as selection gradients (β) and the opportunity for sexual selection (I(s) ), to quantify the actual and/or potential strength of sexual selection acting in natural or experimental populations. In a recent paper, Klug et al. (J. Evol. Biol.23, 2010, 447) contend that selection gradients ar...

Males in many species have complex, multicomponent sexual signals, and there may be trade-offs between different signal components. By adjusting their signaling behaviors, males may be able to produce more attractive courtship displays in the face of these trade-offs, but this possibility has rarely been tested. In this study, we examined adaptive...

In the few species of birds in which males form display partnerships to attract females, one male secures most or all of the copulations. This leads to the question of why subordinate males help in the absence of observable reproductive benefits. Hamilton's concept of kin selection, whereby individuals can benefit indirectly by helping a relative,...

In lekking systems, females can observe both male courtship displays and fights. It has been theorized that male-male agonism may function as a display, giving females more information about mate quality. However, males in many species, such as Greater Sage-grouse, often fight when females are absent, and can even attack during copulation attempts...

Remotely sensed land cover datasets have been increasingly employed in studies of wildlife habitat use. However , meaningful interpretation of these datasets is dependent on how accurately they estimate habitat features that are important to wildlife. We evaluated the accuracy of the GAP dataset, which is commonly used to classify broad cover categ...

We present a statistical approach-a custom-built hidden Markov model (HMM)-that is broadly applicable to the analysis of temporally clustered display events, as found in many animals, including birds, orthopterans, and anurans. This HMM can simultaneously estimate both the expected lengths of each animal's display bouts and their within-bout displa...

An increasing number of threats, both natural (e.g. fires, drought) and anthropogenic (e.g. agriculture, infrastructure development), are likely to affect both availability and quality of plants that grouse rely on for cover and food. As such, there is an increasing need to monitor plants and their use by grouse over space and time to better predic...

Radio-transmitters are used widely in wildlife research because they allow researchers to track individual animals and monitor their activity. However, to provide unbiased information about a population, transmitters must be deployed on a representative sample of animals and must not alter the behavior of the individuals. The greater sage-grouse Ce...

Studies have found that some birds use vocalizations with higher minimum frequency in noisy areas. Minimum frequency is often measured by visual inspection of spectrograms (“by-eye practice” (BEP)), which is prone to bias, e.g., if low-frequency components are masked by noise. We tested for this bias by comparing measurements of minimum frequency o...

In-person counts of sage-grouse at leks are vital for informed sage-grouse management, but conducting these counts can be logistically difficult. Camera traps (i.e. automated trail or wildlife cameras) have been used in conjunction with numerous studies of wildlife species, but rarely on grouse leks. In a pilot study, we deployed five camera traps...

Lateral biases in behaviours are common across animals. Greater laterality may be beneficial if it allows for more efficient neural processing, yet few studies have considered the possible importance of individual variation in lateral biases in wild animals, particularly for social behaviours. We examined lateral biases in lekking greater sage-grou...

Although birds are generally known for their vocally produced songs and calls, some species have evolved alternate means of acoustic communication that do not require the syrinx. While many of these mechanical sounds are used in a courtship context, the importance of among-and within-individual variation in these sounds is almost entirely unknown....

Competition among males for access to reproductive opportunities is a central tenet of behavioural biology that has critical implications for studies of mating systems, sexual selection and the evolution of numerous phenotypic traits. Given the expectation that males should compete vigorously for access to females, it may at first seem paradoxical...

Monitoring of birds often requires the use of very-high-frequency radios or satellite telemetry to enhance detectability of individuals. An assumption implicit in such studies is that radio-marked individuals are representative of the population at whole, which requires that radios do not influence an individual's behavior or demographics. We prese...

Lekking male greater sage-grouse (Centrocercus urophasianus) compete with neighbours not only by strutting to attract females but also by directly challenging other males. These challenges include approaching another male and adopting an anti-parallel orientation at close quarters ('facing past encounter') and fighting, in which the birds strike on...

Lekking male greater sage-grouse (Centrocercus urophasianus) compete with neighbours not only by strutting to attract females but also by directly challenging other males. These challenges include approaching another male and adopting an anti-parallel orientation at close quarters ('facing past encounter') and fighting, in which the birds strike on...

There is increasing evidence that individuals in many species avoid areas exposed to chronic anthropogenic noise, but the impact of noise on those who remain in these habitats is unclear. One potential impact is chronic physiological stress, which can affect disease resistance, survival and reproductive success. Previous studies have found evidence...

Female preference favors the evolution of elaborate male display traits in many species. However, little is known about whether this process of sexual selection also favors males with better courtship skills, such as the ability to respond to female signals. Here we used a robotic female to determine experimentally whether male Sage Grouse, Centroc...

Acoustic sensor arrays can allow researchers to localize the position of vocalizing animals. During the course of research on a threatened bird species, the greater sage-grouse, we developed a 24-channel wired array to non-invasively monitor male courtship displays at traditional display grounds (i.e. leks). Here we describe a study in which we loc...

The high level of genetic relatedness between parents and offspring is a key feature of family groups and is thought to be a major factor stabilizing social interactions within families. However, these families are only one type of persistent animal social group that strikes a balance between conflict and cooperation. In many species, males aggrega...

1. Animals produce sounds for diverse biological functions such as defending territories, attracting mates, deterring predators, navigation, finding food and maintaining contact with members of their social group. Biologists can take advantage of these acoustic behaviours to gain valuable insights into the spatial and temporal scales over which ind...

Economists study negotiation as a series of events—partner choice, information gathering, bargaining, etc.—with each step of the process affecting the outcome of the next, and the optimal decision at each stage depending on the player’s bargaining power. The context in which these negotiations occur—the market—is critical, since players can adjust...

Greater sage-grouse, Centrocercus urophasianus, have been a model system in studies of sexual selection and lek evolution. Mate choice in this species depends on acoustic displays during courtship, yet we know little about how males produce these sounds. Here we present evidence for previously undescribed two-voiced sound production in the sage-gro...

Reproductive skew theory provides a predictive theory of the extent of reproductive sharing that is expected to occur in societies consisting, at least potentially, of multiple co-breeders. Here, we discuss some of the challenges that skew theory faces as it attempts to form the basis of a unified theory of social evolution in birds. These include...

We analyzed the relationship between population abundance and variability of western scrub-jays Aphelocoma californica based on 48 yr of Audubon Christmas Bird Counts and the resources on which they depend as indexed by the diversity and abundance of mast-producing oaks and pines and, for California, estimates of acorn production based on a statewi...

Mode of development in birds helps determine the form of brood parasitism a species exhibits. Most knowledge of precocial brood parasites comes from a single avian family, the waterfowl (Anatidae: Anseriformes). Here we review cases of interspecific brood parasitism (IBP) in a second group of precocial birds, the order Galliformes. IBP is uncommon...

Color patterns commonly vary geographically within species, but it is rare that such variation corresponds with divergent antipredator strategies. The polymorphic salamander Ensatina eschscholtzii, however, may represent such a case. In this species, most subspecies are cryptically colored, whereas E. e. xanthoptica, the Yellow eyed ensatina, is hy...

Molecular measures of parentage provide important insights into the opportunity for sexual selection; in birds, such studies have been conducted almost exclusively on pair-bonded passerines. Here I employ a multitiered parentage analysis involving 10-locus microsatellite genotypes to characterize the genetic mating system of a population of Wild Tu...

The developmental processes producing preferences for opposite-sex mating partners are not well understood. Zebra finches, Taeniopygia guttata, are colonial and socially monogamous with biparental care. To determine whether the early social environment contributes to sexual partner preference, we removed adult males from breeding colonies when the...

Male common loons, Gavia immer, produce a territorial vocalization called the yodel. We quantitatively examined yodels using discriminant and cross correlation analysis. Both techniques correctly assigned the majority of the male's yodels to the proper group, however discriminant analysis was more accurate for making long term comparisons of a yode...

The brown lacewings (Neuroptera: Hemerobiidae) have undergone a spectacular radiation on the Hawaiian Archipelago; currently 23 endemic micromine species are recognized, 19 of which were described by Perkins and four by Zimmerman. Recent systematics studies, using adult morphological characteristics, placed these lacewings in the cosmopolitan genus...

Micromus and Hemerobius are the most common and agriculturally important genera of hemerobiids in North America. Twelve morphological traits (8 cephalic, 4 thoracic) differentiate the larvae of these genera. Additional structural, chaetotaxic, and color traits distinguish M. subanticus (Walker) and M. posticus (Walker) larvae. The larval stages of...