We review the ecological rationale behind the potential compatibility between top predators and biodiversity conservation, and examine their effectiveness as surrogate species. Evidence suggests that top predators promote species richness or are spatio-temporally associated with it for six causative or noncausative reasons: resource facilitation, trophic cascades, dependence on ecosystem productivity, sensitivity to dysfunctions, selection of heterogeneous sites and links to multiple ecosystem components. Therefore, predator-centered conservation may deliver certain biodiversity goals. To this aim, predators have been employed in conservation as keystone, umbrella, sentinel, flagship, and indicator species. However, quantitative tests of their surrogate-efficacy have been astonishingly few. Evidence suggests they may function as structuring agents and biodiversity indicators in some ecosystems but not others, and that they perform poorly as umbrella species; more consensus exists for their efficacy as sentinel and flagship species. Conservation biologists need to use apex predators more cautiously, as part of wider, context-dependent mixed strategies.

Some conservation organizations publish magazines that showcase current conservation and research projects, attract new subscribers and maintain membership, often using flagship species to promote these objectives. This study investigates the nature of flagship species featured on the covers of ten representative US conservation and nature magazines, Defenders, National Wildlife, Wildlife Conservation, Zoonooz, Nature Conservancy, Outdoor America, Sierra, Audubon, California Wild and Natural History. Operationally defining flagship species by diet, taxonomic order, body size and IUCN status, we found that magazines tend to use mammal and bird species rather than invertebrate, fish, amphibian, reptile or plant taxa on their covers. Featured birds were mostly omnivorous or piscivorous, large-bodied and of little conservation concern; featured mammals were mainly carnivorous or herbivorous, large-bodied and of considerable conservation concern. These analyses confirm, for the first time, anecdotal observations about conservation organizations focusing their publicity and programmes on large, charismatic species to raise awareness and funds and raise the spectre that the public may be exposed to only a selected sample of conservation problems.

Extensive research over the last few decades has revealed that many acoustically communicating animals compensate for the masking effect of background noise by changing the structure of their signals. Familiar examples include birds using acoustic properties that enhance the transmission of vocalizations in noisy habitats. Here, we show that the effects of background noise on communication signals are not limited to the acoustic modality, and that visual noise from windblown vegetation has an equally important influence on the production of dynamic visual displays. We found that two species of Puerto Rican lizard, Anolis cristatellus and A. gundlachi, increase the speed of body movements used in territorial signalling to apparently improve communication in visually 'noisy' environments of rapidly moving vegetation. This is the first evidence that animals change how they produce dynamic visual signals when communicating in noisy motion habitats. Taken together with previous work on acoustic communication, our results show that animals with very different sensory ecologies can face similar environmental constraints and adopt remarkably similar strategies to overcome these constraints.

Correlations between urbanization and biodiversity are well known, but the causes driving such associations are lacking. We used a long-term, quasi-experimental approach to study the responses of avian communities to suburban and exurban development around Seattle, WA, USA. We measured indices of bird abundance, reproduction, and survival for 12 years at many locations, including 5 forest 'reserves,' 10 existing 'developments,' and 11 'changing' sites where ongoing development converted forests to single-family residential neighborhoods. In the first few years of clearing, building, and occupation of new neighborhoods by humans avian communities shifted from those typical of second-growth forest to those more characteristic of developments. During this time avian diversity increased and numerical dominance by abundant birds declined. Species that adapted and exploited development reproduced more successfully there than did forest-dependent species that avoided development. Adults of species that thrived in developments attained equal annual survival across reserved to developed landscapes, while species that avoided neighborhoods tended to survive poorly outside of reserves. The humans living in our study areas frequently fed birds and provided nest boxes. These actions were positively correlated with increases in secondary cavity nesting and seed eating birds. Humans also maintained outdoor cats and 11 % of humans both fed birds and let their cats outside. These actions were negatively correlated with the abundance of birds regularly using feeders. We suggest that a key management goal in urban ecosystems is the maintenance of avian diversity because a diverse avifauna engages a diversity of humans.

Interactions between species can lead to the evolution of interspecific communication. Non‐verbal communication by humans, both intentional and unintentional, can be interpreted by other species. We tested whether American crows (Corvus brachyrhynchos) were sensitive to human facial features under field conditions by comparing flight initiation distances and urgency of escape behavior to human approaches varying in eye contact and facial expression. We first examined whether crows distinguish between an approaching human who is directly gazing at them and a human approaching them with an averted gaze. In a second experiment, we tested whether crows differentiate a smiling from scowling human approaching them with direct or averted gaze. In the first experiment, we found that crows fled sooner and more urgently when humans were directly gazing at them. Similarly, in the second experiment, crows responded sooner to a direct vs. averted gaze; however, they did not react differently to varying human facial expressions. We suggest that crows use human gaze as a reliable visual cue compared with facial expressions when making decisions about responding to approaching humans. This is the first study to show that a wild corvid species changes its behavior based on human gaze, possibly representing an adaptation to living in human‐dominated urban areas and suggesting crows might perceive human intention by this visual cue.

Humans profoundly affect wildlife through environmental modification but they can also influence wildlife through direct interactions. We surveyed human attitudes and actions towards birds in two urban areas (Seattle, Washington, and Berlin, Germany) to determine whether encouraging (e.g., providing bird feeders) and discouraging (e.g., actively repelling) behavior directed at birds affected bird behavior. We studied human and bird behavior across an urbanization gradient (heavy to light urbanization) in both cities to capture variation in urban cover, human density, attitudes, and actions as well as variation in human culture and socioeconomic condition and education. We found that residents of Berlin encouraged birds more than residents of Seattle did, and that Seattleites discouraged birds more than Berliners. These differences varied across the urbanization gradient. Likewise, birds (crows and other songbirds) varied their flight initiation distance across the urbanization gradient, with distances increasing from urban to rural sites. However, in rural sites in Seattle, American Crows (Corvus brachyrhynchos) and European Starlings (Sturnus vulgaris) had exaggerated flight initiation distances compared with those of American Robins (Turdus migratorius) in Seattle and those of Hooded Crows (C. cornix), House Sparrows (Passer domesticus), and European Starlings in rural Berlin. This exaggerated wariness of humans in crows and starlings is correlated with the relatively high levels of discouraging behavior toward birds by humans in these rural areas in Seattle. These results demonstrate that in addition to habituation to human disturbance, human behavior directed at birds can affect certain species' behavior.

No abstract

No abstract