Tonya M. Haff

Calling at a cost: elevated nestling calling attracts predators to active nests

Begging by nestling birds has been used to test evolutionary models of signalling but theory has outstripped evidence. Eavesdropping predators potentially impose a cost on begging that ensures signal honesty, yet little experimental evidence exists for such a cost at active nests because the use of artificial nests, long playback bouts and absence of parents may have exaggerated costs. We broadcast short periods (1 h) of either nestling vocalizations or background noise at active white-browed scrubwren, Sericornis frontalis, nests. Nestlings called naturally during both treatments, allowing us to test whether elevated calling increases risk, a key but rarely tested assumption of evolutionary models. Predators visited nests exclusively during periods of elevated calling. Furthermore, playbacks affected neither adult visits nor nestling activity, suggesting that calling alone attracted predators. Adults gave alarm calls and nestlings usually called less when predators approached nests. Predation risk to broods is, therefore, likely to fluctuate substantially over short periods of time, depending on nestling hunger and whether adults or young have detected predators. This study confirms a present-day cost of nestling begging, demonstrates that this cost can be incurred over short periods and supports the importance of parent–offspring antipredator strategies in reducing predation risk.

Calling in the Face of Danger: Predation Risk and Acoustic Communication by Parent Birds and Their Offspring

Abstract Birds raise their young under constant risk of predation, which shapes how parents and young communicate acoustically. Nestling begging calls extract care from parents but expose them to eavesdropping by predators, which selects for cryptic signal design. However, for largely unknown reasons, nestlings often call even when parents are absent and thus unavailable for defense. Nestlings can give distress and defensive calls, but their efficacy is unknown. Parental alarm calls warn young of danger in some species, and young can show adaptive changes in response according to their age-related vulnerability to specific predators. Parents often signal their arrival at the nest with provisioning calls, which might reduce mistaken begging and increase the efficiency of feeding, and thereby minimize detection by predators. Acoustic interactions between offspring and parents can lead to young either remaining silent until prompted by a parents provisioning call, or begging indiscriminately to subtle cues of arrival while remaining alert to parental alarm calls. Young can also assess danger independently of parents, which could in turn affect parental decisions about giving alarm calls. All these behaviors offer fertile ground for studying how animals trade off acoustic communication with the risk of eavesdropping.

Nest predation research: Recent findings and future perspectives

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 within nest predation interactions: adults, offspring and predators. Indeed, the study of nest predation now forms a vital part of avian research in several fields, including animal behaviour, population ecology, evolution and conservation biology. However, within nest predation research there are important aspects that require further development, such as the comparison between ecological and evolutionary antipredator responses, and the role of anthropogenic change. We hope this review of recent findings and the presentation of new research avenues will encourage researchers to study this important and interesting selective pressure, and ultimately will help us to better understand the biology of birds.

Troubleshooting Public Data Archiving: Suggestions to Increase Participation

Public data archiving has many benefits for society, but some scientists are reluctant to share their data. This Perspective offers some practical solutions to reduce costs and increase benefits for individual researchers.

To call or not to call: parents assess the vulnerability of their young before warning them about predators.

Communication about predators can reveal the effects of both conspecific and heterospecific audiences on signalling strategy, providing insight into signal function and animal cognition. In species that alarm call to their young, parents face a fundamental dilemma: calling can silence noisy offspring and so make them less likely to be overheard, but can also alert predators that young are nearby. Parents could resolve this dilemma by being sensitive to the current vulnerability of offspring, and calling only when young are most at risk. Testing whether offspring vulnerability affects parental strategy has proved difficult, however, because more vulnerable broods are often also more valuable. We tested experimentally whether parent white-browed scrubwren, Sericornis frontalis, assessed brood noisiness when alarm calling near nests. When a model predator was nearby, parents gave more alarm calls when playbacks simulated noisy broods, yet brood noisiness did not affect adult calling when only a control model was present. Parents were therefore sensitive to the tradeoff between silencing young and alerting predators to the presence of nests. Our study demonstrates that receiver vulnerability can affect signalling decisions in species other than primates.

Trees, Truffles, and Beasts: How Forests Function by Chris Maser, Andrew W. Claridge, and James M. Trappe

Forests are an integral part of human life. In addition to producing lumber and economic livelihood, they are a rich source of biological capital and provide ecosystem services, such as clean air and water, upon which we depend. Yet our understanding of the interconnections and coevolution that profoundly affect how forests work remains woefully underdeveloped. This lack of understanding, and moreover our delusions of having control over nature, hampers proper forest management, threatens the continued health and function of forests, and degrades the future of organisms that are an integral part of forest ecosystems—including humankind. This is the underlying premise of Trees, Truffles, and Beasts, which explores many unseen forest inhabitants and processes in an approachable style that is easily accessible to foresters, biologists, and lay people alike. The scope of Trees, Truffles, and Beasts is, ambitiously, to examine forests “from microlevel to infinity.” The diverse background of the authors allows them to accomplish this goal relatively successfully. Chris Maser has written a variety of books on forest ecology, natural history, and sustainability, and both Andrew Claridge (New South Wales Parks and Wildlife Division, Australia) and Jim Trappe (Oregon State University, United States) have written extensively about forest ecosystems, fungi, mammals, and the interactions between the three. The result is a book that emphasizes a holistic approach to understanding forests by examining the convergence in processes, function, and human (mis)management of forests on opposite sides of the world: the Pacific North west of the United States, and southeastern Australia. As a recent transplant from northern California to southeastern Australia, I found this book particularly useful in illustrating the similarities between what on the surface appear to be antipodal worlds. The first half of the book builds the reader’s basic understanding of similarities in forest structure, composition, and function be tween North America and Australia. We are introduced to “the forest we see” in both locations—the dominant climates, weather patterns, and flora of the forests. The book then focuses on what the authors clearly find most compelling—the unseen web of interconnections and coevolution between trees, fungi, soil micro organisms, and animals that underpin forest function. To familiarize readers with the forest inhabitants, the book jumps back and forth between continents, giving species accounts in brief, natural-history-guide style. Readers will be challenged to find any other book that details how, for example, Douglas-fir (Pseudotsuga douglasii) and messmate stringybark (Eucalyptus obliqua) compare in their functional roles in forests, or that explores the commonalities between California red-backed voles (Myodes californicus) and long-footed potaroos (Potorous longipes). However, those who find scientific names useful will be frustrated by their conspicuous absence throughout most of the book; Latin names are tucked away in 2 unreferenced appendices. The authors devote considerable attention to an introduction to general mycology, and to the role that mushroom-producing fungi play in affecting forest composition and health. They provide many fascinating examples of the trophic roles fungi play in forest environments but focus most of their efforts on mycorrhizal truffles (fungi that produce underground “mushrooms” that are consumed by animals) and the mycophagous animals that disperse their spores. In particular, the authors emphasize how truffles provide critical nutritional rewards such as vitamins, protein, and fatty acids for mycophagous mammals, and how mycophagy provides critical ecosystem services such as improving soil moisture content, Western North American Naturalist 69(3),