Search

Resolving the consequences of pollinator foraging behaviour for plant mating systems is a fundamental challenge in evolutionary ecology. Pollinators may adopt particular foraging tactics: complete trapline foraging (repeated movements along a fixed route), sample-and-shift trapline foraging (a variable route that incorporates information from previous experiences) and territorial foraging (stochastic movements within a restricted area). Studies that integrate these pollinator foraging tactics with plant mating systems are generally lacking. We investigate the consequences of particular pollinator foraging tactics for Heliconia tortuosa. We combine parentage and sibship inference analysis with simulation modelling to: estimate mating system parameters; infer the foraging tactic adopted by the pollinators; and quantify the impact of pollinator foraging tactics on mating system parameters. We found high outcrossing rates, ubiquitous multiple paternity and a pronounced departure from near-neighbour mating. We also found that plants repeatedly receive pollen from a series of particular donors. We infer that the pollinators primarily adopt complete trapline foraging and occasionally engage in sample-and-shift trapline foraging. This enhances multiple paternity without a substantial increase in near-neighbour mating. The particular pollinator foraging tactics have divergent consequences for multiple paternity and near-neighbour mating. Thus, pollinator foraging behaviour is an important driver of the ecology and evolution of plant mating systems.

Climate change is contributing to biodiversity redistributions and species declines. However, cooler microclimate conditions provided by old-growth forest structures compared with surrounding open or younger forests have been hypothesized to provide thermal refugia for species that are sensitive to climate warming and dampen the negative effects of warming on population trends of animals (i.e., the microclimate buffering hypothesis). In addition to thermal refugia, the compositional and structural diversity of old-growth forest vegetation itself may provide resources to species that are less available in forests with simpler structure (i.e., the insurance hypothesis). We used 8 years of breeding bird abundance data from a forested watershed, accompanied with sub-canopy temperature data, and ground- and LiDAR-based vegetation data to test these hypotheses and identify factors influencing bird population changes from 2011 to 2018. After accounting for imperfect detection, we found that for 5 of 20 bird species analyzed, abundance trends tended to be less negative or neutral at sites with cooler microclimates, which supports the microclimate buffering hypothesis. Negative effects of warming on two species were also reduced in locations with greater forest compositional diversity supporting the insurance hypothesis. We provide the first empirical evidence that complex forest structure and vegetation diversity confer microclimatic advantages to some animal populations in the face of climate change. Conservation of old-growth forests, or their characteristics in managed forests, could help slow the negative effects of climate warming on some breeding bird populations via microclimate buffering and possibly insurance effects.

Species sensitivity to forest fragmentation varies latitudinally, peaking in the tropics. A prominent explanation for this pattern is that historical landscape disturbance at higher latitudes has removed fragmentation-sensitive species or promoted the evolution of more resilient survivors. However, it is unclear whether this so-called extinction filter is the dominant driver of geographic variation in fragmentation sensitivity, particularly because climatic factors may also cause latitudinal gradients in dispersal ability, a key trait mediating sensitivity to habitat fragmentation. Here we combine field survey data with a morphological proxy for avian dispersal ability (hand-wing index) to assess responses to forest fragmentation in 1,034 bird species worldwide. We find that fragmentation sensitivity is strongly predicted by dispersal limitation and that other factors—latitude, body mass and historical disturbance events—have relatively limited explanatory power after accounting for species differences in dispersal. We also show that variation in dispersal ability is only weakly predicted by historical disturbance and more strongly associated with intra-annual temperature fluctuations (seasonality). Our results suggest that climatic factors play a dominant role in driving global variation in the impacts of forest fragmentation, emphasizing the need for more nuanced environmental policies that take into account local context and associated species traits.

One of landscape ecology's main goals is to unveil how biodiversity is impacted by habitat transformation. However, the discipline suffers from significant context dependency in observed spatial and temporal trends, hindering progress towards understanding the mechanisms driving species declines and preventing the development of accurate estimates of future biodiversity change. Here, we discuss recent evidence that populations' and species' responses to habitat change at the landscape scale are modulated by factors and processes occurring at macroecological scales, such as historical disturbance rates, distance to geographic range edges, and climatic suitability. We suggest that placing landscape ecology studies in a macroecological lens will help to explain seemingly inconsistent results and will ultimately create better predictive models to help mitigate the biodiversity crisis.

In many regions of the world, forest management has reduced old forest and simplified forest structure and composition. We hypothesized that such forest degradation has resulted in long-term habitat loss for forest-associated bird species of eastern Canada (130,017 km2) which, in turn, has caused bird-population declines. Despite little change in overall forest cover, we found substantial reductions in old forest as a result of frequent clear-cutting and a broad-scale transformation to intensified forestry. Back-cast species distribution models revealed that breeding habitat loss occurred for 66% of the 54 most common species from 1985 to 2020 and was strongly associated with reduction in old age classes. Using a long-term, independent dataset, we found that habitat amount predicted population size for 94% of species, and habitat loss was associated with population declines for old-forest species. Forest degradation may therefore be a primary cause of biodiversity decline in managed forest landscapes.

Climate change impacts are accelerating and there is an urgent need to address this global issue. Tackling climate change in an effective and socially just manner needs to involve mitigation strategies that address the underlying causes of climate change, but also adaptation strategies that help us prepare for current and future impacts. Historically, mitigation and adaptation strategies have been treated separately, but there is now growing awareness of important synergies between them. We highlight these synergies across six key areas where humans need to make transformative changes in order to reduce the impacts of climate change, including energy, pollutants, nature, food, population and the economy. In doing so, we show the enormous potential for civil society, government, world leaders and the private sector to take advantage of the fact that mitigation strategies can also provide adaptation opportunities to lessen humanity’s suffering as we navigate the uncertainties of the climate crisis.

The ecological co-dependency between plants and hummingbirds is a classic example of a mutualistic interaction: hummingbirds rely on floral nectar to fuel their rapid metabolisms, and more than 7000 plant species rely on hummingbirds for pollination. However, threats to hummingbirds are mounting, with 10% of 366 species considered globally threatened and 60% in decline. Despite the important ecological implications of these population declines, no recent review has examined plant–hummingbird interactions in the wider context of their evolution, ecology, and conservation. To provide this overview, we (i) assess the extent to which plants and hummingbirds have coevolved over millions of years, (ii) examine the mechanisms underlying plant–hummingbird interaction frequencies and hummingbird specialization, (iii) explore the factors driving the decline of hummingbird populations, and (iv) map out directions for future research and conservation. We find that, despite close associations between plants and hummingbirds, acquiring evidence for coevolution (versus one-sided adaptation) is difficult because data on fitness outcomes for both partners are required. Thus, linking plant–hummingbird interactions to plant reproduction is not only a major avenue for future coevolutionary work, but also for studies of interaction networks, which rarely incorporate pollinator effectiveness. Nevertheless, over the past decade, a growing body of literature on plant–hummingbird networks suggests that hummingbirds form relationships with plants primarily based on overlapping phenologies and trait-matching between bill length and flower length. On the other hand, species-level specialization appears to depend primarily on local community context, such as hummingbird abundance and nectar availability. Finally, although hummingbirds are commonly viewed as resilient opportunists that thrive in brushy habitats, we find that range size and forest dependency are key predictors of hummingbird extinction risk. A critical direction for future research is to examine how potential stressors – such as habitat loss and fragmentation, climate change, and introduction of non-native plants – may interact to affect hummingbirds and the plants they pollinate.

Mutualistic relationships, such as those between plants and pollinators, may be vulnerable to the local extinctions predicted under global environmental change. However, network theory predicts that plant–pollinator networks can withstand species loss if pollinators switch to alternative floral resources (rewiring). Whether rewiring occurs following species loss in natural communities is poorly known because replicated species exclusions are difficult to implement at appropriate spatial scales.We experimentally removed a hummingbird-pollinated plant, Heliconia tortuosa, from within tropical forest fragments to investigate how hummingbirds respond to temporary loss of an abundant resource. Under the rewiring hypothesis, we expected that niche expansions would decrease ecological specialization and reorganize the network structure (i.e., pairwise interactions).We employed a replicated Before-After-Control-Impact experimental design and quantified plant–hummingbird interactions using two parallel sampling methods: observations of hummingbirds visiting focal plants (‘camera networks’, created from >19,000 observation hours) and pollen collected from individual hummingbirds (‘pollen networks’, created from >300 pollen samples). To assess hummingbird rewiring, we quantified ecological specialization at the individual, species, and network levels and calculated the amount of network-level interaction turnover (i.e., gain/loss of pairwise interactions). Leveraging our parallel network datasets, we also explored how sampling method influences apparent specialization.H. tortuosa removal caused some reorganization of pairwise interactions but did not prompt large changes in specialization, despite the large magnitude of our manipulation (on average, >100 inflorescences removed in treatment areas of >1 ha). Although some individual hummingbirds sampled through time showed modest increases in niche breadth following Heliconia removal (relative to birds that did not experience resource loss), these changes were not reflected in species- and network-level specialization metrics. We also found that camera networks were more specialized than pollen networks, and that correlation between sampling methods was low.Our results suggest that animals may not necessarily shift to alternative resources after losing an abundant food resource, even in species thought to be highly opportunistic foragers such as hummingbirds. Given that rewiring contributes to theoretical predictions of network stability, future studies should investigate why pollinators might not expand their diets after a local resource extinction.

Concerns about long-term pollinator declines have made assessing bee communities a priority in nonagricultural ecosystems, including managed forests. We assessed wild bee communities in Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) stands one to 15 years after clearcut harvest in western Oregon, USA, testing the hypothesis that bee diversity would be high initially and then decline with time-dependent reductions in floral resources. We captured 2,009 individual bees that represented 67 distinct species/morphospecies in 20 genera and five families. Asymptotic estimators of bee diversity representing Shannon and Simpson diversity were greater in communities during the second half of the early seral period, indicating older early seral stands were less diverse and contained more common and dominant bee species. In addition, observed species richness and bee abundance peaked at approximately three years postharvest and declined thereafter by 20% and 30% per year, respectively. Because floral resources declined in concert with reductions in bee diversity as stands aged, food appears to be a key driver of forest bee communities. Our results indicate that postharvest Douglas-fir stands supported a diversity of bees, including important crop pollinators, but their value to bees was restricted to a relatively short window at the beginning of the early seral period.

Research hypotheses have been a cornerstone of science since before Galileo. Many have argued that hypotheses (1) encourage discovery of mechanisms, and (2) reduce bias—both features that should increase transferability and reproducibility. However, we are entering a new era of big data and highly predictive models where some argue the hypothesis is outmoded. We hypothesized that hypothesis use has declined in ecology and evolution since the 1990s, given the substantial advancement of tools further facilitating descriptive, correlative research. Alternatively, hypothesis use may have become more frequent due to the strong recommendation by some journals and funding agencies that submissions have hypothesis statements. Using a detailed literature analysis (N = 268 articles), we found prevalence of hypotheses in eco–evo research is very low (6.7%–26%) and static from 1990–2015, a pattern mirrored in an extensive literature search (N = 302,558 articles). Our literature review also indicates that neither grant success nor citation rates were related to the inclusion of hypotheses, which may provide disincentive for hypothesis formulation. Here, we review common justifications for avoiding hypotheses and present new arguments based on benefits to the individual researcher. We argue that stating multiple alternative hypotheses increases research clarity and precision, and is more likely to address the mechanisms for observed patterns in nature. Although hypotheses are not always necessary, we expect their continued and increased use will help our fields move toward greater understanding, reproducibility, prediction, and effective conservation of nature., We use a quantitative literature review to show that use of a priori hypotheses is still rare in the fields of ecology and evolution. We provide suggestions about the group and individual‐level benefits of hypothesis use.

Protected areas are a key tool in the conservation of global biodiversity and carbon stores. We conducted a global test of the degree to which more than 18,000 terrestrial protected areas (totalling 5,293,217 km2) reduce deforestation in relation to unprotected areas. We also derived indices that quantify how well countries’ forests are protected, both in terms of forested area protected and effectiveness of protected areas at reducing deforestation, in relation to vertebrate species richness, aboveground forest carbon biomass and background deforestation rates. Overall, protected areas did not eliminate deforestation, but reduced deforestation rates by 41%. Protected area deforestation rates were lowest in small reserves with low background deforestation rates. Critically, we found that after adjusting for effectiveness, only 6.5%—rather than 15.7%—of the world’s forests are protected, well below the Aichi Convention on Biological Diversity’s 2020 Target of 17%. We propose that global targets for protected areas should include quantitative goals for effectiveness in addition to spatial extent. A global analysis of deforestation rates in more than 18,000 terrestrial protected areas shows that, once protected area effectiveness is taken into account, only 6.5%—rather than 15.7%—of the world’s forests are protected, well below the Aichi Target of 17%.

Theory predicts that the structure of plant-pollination networks should withstand disturbance, but experiments testing this prediction remain uncommon. In this study, we simulated the local extinction of a hummingbird-pollinated understory plant,Heliconia tortuosa, from tropical forest fragments using a replicated Before-After-Control-Impact design while quantifying hummingbird abundance and space use (383 hummingbird captures and 72 radio-tagged individuals), floral visitation rates (>19,000 observation hours), and pollination success (529 flowers). We expected thatH. tortuosaremoval would either result in (i) network collapse, in which hummingbirds vacate fragments and compromise the reproductive success of other flowering plants, or (ii) increased hummingbird reliance on alternative resources (rewiring), leading to sustained fragment use. In our experiment, hummingbird behavior and pollination were remarkably resistant to loss ofH. tortuosa, a locally common plant species representing 30-40% of the available nectar resources on average. The exact mechanisms enabling short-term hummingbird persistence after resource removal remain unclear, as we did not discover evidence of rewiring. We hypothesize that physiological adaptations (e.g., torpor and insectivory) may have allowed hummingbird persistence, perhaps alongside high movement ability. With the important caution that short-term experiments may not emulate natural extinction processes, our study provides support for predictions that pollination networks may be robust to plant species loss.

Protected areas (PAs) constitute one of the main tools for global landscape conservation. Recently, payments for environmental services (PES) have attracted interest from national and regional governments and are becoming one of the leading conservation policy instruments in tropical countries. However, the degree to which areas designated for PES overlap with areas that are critical for maintaining species' landscape connectivity is rarely evaluated. We estimated habitat distributions and connectivity for 16 of the 22 mammalian carnivores occurring in the Caribbean region of Colombia, and identified the overlap between existing PAs and areas identified as being important for connectivity for these species. We also evaluated the potential impact of creation of new PAs versus new PES areas on conserving connectivity for carnivores. Our results show that PAs cover only a minor percentage of the total area that is important for maintaining connectivity (x=26.8%±20.2 s.d.). On the other hand, PES, if implemented extensively, could contribute substantially to mammalian carnivores’ connectivity (x=45.4%±12.8 s.d.). However, in a more realistic scenario with limited conservation investment in which fewer areas are set aside, a strategy based on implementing new PAs seems superior to PES. We argue that prioritizing designation of new PAs will be the most efficient means through which to maintain connectivity.

Understanding how land-management intensification shapes the relationships between biodiversity, yield, and economic benefit is critical for managing natural resources. Yet, manipulative experiments that test how herbicides affect these relationships are scarce, particularly in forest ecosystems where considerable time lags exist between harvest revenue and initial investments. We assessed these relationships by combining 7 yr of biodiversity surveys (>800 taxa) and forecasts of timber yield and economic return from a replicated, large-scale experiment that manipulated herbicide application intensity in operational timber plantations. Herbicides reduced species richness across trophic groups (-18%), but responses by higher-level trophic groups were more variable (0-38% reduction) than plant responses (-40%). Financial discounting, a conventional economic method to standardize past and future cash flows, strongly modified biodiversity-revenue relationships caused by management intensity. Despite a projected 28% timber yield gain with herbicides, biodiversity-revenue trade-offs were muted when opportunity costs were high (i.e., economic discount rates ≥7%). Although herbicides can drive biodiversity-yield trade-offs, under certain conditions, financial discounting provides opportunities to reconcile biodiversity conservation with revenue.

Many ecologists have lamented the demise of natural history and have attributed this decline to a misguided view that natural history is outdated and unscientific. Although there is a perception that the focus in ecology and conservation have shifted away from descriptive natural history research and training toward hypothetico-deductive research, we argue that natural history has entered a new phase that we call “next-generation natural history.” This renaissance of natural history is characterized by technological and statistical advances that aid in collecting detailed observations systematically over broad spatial and temporal extents. The technological advances that have increased exponentially in the last decade include electronic sensors such as camera-traps and acoustic recorders, aircraft- and satellite-based remote sensing, animal-borne biologgers, genetics and genomics methods, and community science programs. Advances in statistics and computation have aided in analyzing a growing quantity of observations to reveal patterns in nature. These robust next-generation natural history datasets have transformed the anecdotal perception of natural history observations into systematically collected observations that collectively constitute the foundation for hypothetico-deductive research and can be leveraged and applied to conservation and management. These advances are encouraging scientists to conduct and embrace detailed descriptions of nature that remain a critically important component of the scientific endeavor. Finally, these next-generation natural history observations are engaging scientists and non-scientists alike with new documentations of the wonders of nature. Thus, we celebrate next-generation natural history for encouraging people to experience nature directly.

In many regions of the world, forest management has reduced old forest and simplified forest structure and composition via reliance on monoculture tree plantations. We hypothesized that such forest degradation has resulted in long-term habitat loss for forest-associated bird species of eastern Canada (130,017 km2) which, in turn, has affected bird population declines. Back-cast species distribution models revealed that despite little change in overall forest cover, breeding habitat loss occurred for 66% of the 54 most common species from 1985-2020. This habitat loss was strongly associated with population declines for 72% of species, as quantified in an independent, long-term dataset. Since 1985, net forest bird abundance has declined in this region by an estimated 33-104 million birds due to habitat loss alone. The effects of forest degradation may therefore be a primary cause of biodiversity decline in managed forest landscapes.

In many regions of the world, forest management has reduced old forest and simplified forest structure and composition. We hypothesized that such forest degradation has resulted in long-term habitat loss for forest-associated bird species of eastern Canada (130,017 km

The relative importance of habitat fragmentation versus loss on species richness has been much debated. However, recent findings that fragmentation effects are relatively weak may be an artifact of using human-classified vegetation rather than adopting a species-eye view to measure landscape structure. We present the first example of a species-centered approach for examining fragmentation effects on ecological communities. We tested hypotheses relating to the relative influence of habitat amount, configuration, and focal patch size on southwest Oregon bird communities. We used boosted regression trees based on unclassified Landsat TM to create ‘stacked’ species distribution models (S-SDMs) for a large pool of avian species and nested subset of habitat specialists. We tested the relative importance of S-SDM-derived habitat amount, patch number, mean patch size, and focal patch size in explaining species richness. We compared this approach to metrics based on generic land-cover classifications. Species-centered models had greater statistical support than land-cover models. In species-centered models, species richness increased as a function of focal patch size and decreased with patch number, supporting the hypothesis of negative effects of fragmentation per se. Land-cover based models indicated inconsistent support for habitat amount but a positive effect of fragmentation. The species-centered approach identified habitat configuration relationships obscured by land-cover based approaches. While positive land-cover based fragmentation effects were consistent with recent synthesis work, the species-centered approach consistently revealed strong negative effects of fragmentation matching traditional theoretical expectations. S-SDMs may offer promise for generalizing ecological theory to real species distributions.

Significance The Northwest Forest Plan (NWFP) ended clearcutting of old-growth forest on federal land across western Washington, Oregon, and California in the early 1990s. We provide a test of how this dramatic change affected bird populations—a commonly used biodiversity indicator. Although the NWFP greatly reduced losses of older forests to logging, losses to wildfire have increased, and declines in birds associated with older forests have amplified. The area of early-seral ecosystems with broadleaf trees stabilized on federal land, but declines continue for some associated species. Creation of early-seral vegetation may be justified in some landscapes where wildfires are mostly suppressed, but should not impede development of older forests, the gradual recovery of which remains critical for the long-term success of the NWFP., The Northwest Forest Plan (NWFP) initiated one of the most sweeping changes to forest management in the world, affecting 10 million hectares of federal land. The NWFP is a science-based plan incorporating monitoring and adaptive management and provides a unique opportunity to evaluate the influence of policy. We used >25 years of region-wide bird surveys, forest data, and land-ownership maps to test this policy’s effect on biodiversity. Clearcutting decreased rapidly, and we expected populations of older-forest–associated birds to stabilize on federal land, but to continue declining on private industrial lands where clearcutting continued. In contrast, we expected declines in early-seral–associated species on federal land because of reduced anthropogenic disturbance since the NWFP. Bayesian hierarchical models revealed that bird species’ population trends tracked changes in forest composition. However, against our expectations, declines of birds associated with older forests accelerated. These declines are partly explained by losses of older forests due to fire on federal land and continued clearcutting elsewhere. Indeed, the NWFP anticipated that reversing declines of older forests would take time. Overall, the early-seral ecosystem area was stable, but declined in two ecoregions—the Coast Range and Cascades—along with early-seral bird populations. Although the NWFP halted clearcutting on federal land, this has so far been insufficient to reverse declines in older-forest–associated bird populations. These findings underscore the importance of continuing to prioritize older forests under the NWFP and ensuring that the recently proposed creation of early-seral ecosystems does not impede the conservation and development of older-forest structure.

Theory predicts that movement limitation due to landscape fragmentation can reduce population viability. Understanding how landscape heterogeneity influences movement is thus critical for testing theory and developing conservation strategies. Consequently, studies are needed that link movement data with landscape features influencing dispersal. We used experimental translocations to test whether forest fragmentation constrains movements of two fragmentation-sensitive bird species. We also tested for evidence of multiple behavioral movement phases (i.e., exploring, homing) and evaluated whether fragmentation effects varied between them. Over two breeding seasons we translocated territorial Wood Thrushes (Hylocichla mustelina; n = 36) and Ovenbirds (Seiurus aurocapilla; n = 19) 1–1.2 km across landscapes spanning a fragmentation gradient and recorded spatial (movement path) and temporal (return time) homing data using VHF transmitters and receivers. Ninety-one percent of individuals returned home, taking up to 72.2 h. Movements of 98% of returning birds indicated distinct exploring (i.e., short, undirected movements and course reversals) and homing (i.e., large, fast steps towards home) movement phases. Both species chose steps minimizing gap exposure in both phases. However, landscape fragmentation had no negative effect on homing times or path straightness. Our results suggest movement limitation does not drive fragmentation sensitivity in these species. Discrepancy between step- and path-level analyses either indicate that fine-scale movement data do not reflect landscape connectivity, or that artificially motivated animals respond unnaturally to behavioral barriers. Given evidence for dichotomous movement behavior, future studies linking these behaviors to life stages will elucidate when and how landscape features influence movement.

Context Land-cover and climate change are predicted to affect pollination and plant reproduction but few studies have tested how these stressors interact to drive pollination success.Objectives Using a 9-year dataset we tested whether climate interacts synergistically with forest loss and fragmentation to affect pollination of a tropical understory herb, Heliconia tortuosa. We hypothesized that hot and/or dry conditions might amplify effects of habitat loss and fragmentation, leading to declines in plant reproduction.Methods We collected data on pollen tubes, fruits and seeds of H. tortuosa in a mensurative experiment representing gradients in forest amount and patch size (N=40 focal-patch landscapes). We modeled these reproductive metrics as a function of landscape composition, configuration, precipitation, temperature, and statistical interactions among these variables.Results We found little support for synergistic landscape and climate effects. However, probability of fruit production decreased in wet years, and increased in large patches embedded in more contiguous forest landscapes. Counterintuitively, small patches in heavily deforested landscapes also exhibited a high probability of fruit – perhaps due to constraints on hummingbird movement. Amount of H. tortuosa fruit decreased in wet years and in deforested landscapes. Conclusion Although we did not detect synergistic effects, climate and landscape structure do have independent impacts on plant reproduction. Unfortunately, the regional climate is predicted to become wetter and the forest remains fragmented, with potential negative consequences for Heliconia reproduction. Decline in this common species is likely to have cascading consequences for hummingbird pollinators, and subsequently other hummingbird dependent plant species.

Conspecific presence can indicate the location or quality of resources, and animals settling near conspecifics often gain fitness benefits. This can result in adaptive conspecific attraction during breeding habitat selection as demonstrated in numerous terrestrial, territorial birds. There is growing interest in using simulated conspecific social cues (e.g., decoys, broadcasted vocalizations) to manage bird distributions, yet it remains unclear when this approach is likely to succeed. We reviewed published studies to evaluate whether the strength of conspecific attraction in terrestrial birds is mediated by characteristics of species (life history traits), simulated cues (e.g., timing and duration), sites (e.g., quality), and how conspecific attraction was measured. We identified 31 experiments that simulated social cues and compared conspecific settlement between treatment and control sites. We then used phylogenetically controlled meta-regression to assess the impacts of 19 moderators on settlement. Nearly all species included in these experiments were migratory passerines, and social cues generally had a strong, positive influence on their settlement decisions, as the odds of site occupancy were 3.12× (95% CI: 0.81–11.69) greater in treatment sites relative to control sites. Within this group, conspecific attraction was evolutionarily conserved with ≥25.5% (95% CI: 5.1%–65.4%) of the variance in treatment effects explained by phylogenetic relatedness. However, we found no evidence that any covariates influenced the response to social cues, and we posit this stems from limited research specifically designed to identify the mechanisms mediating conspecific attraction. We therefore developed a research agenda that provides a framework for testing mechanistic hypotheses regarding how cue characteristics, species traits, and spatial contexts may mediate attraction to conspecifics. Evaluating these hypotheses will greatly advance the field by helping managers understand when, where, and why simulating social cues can be used to enhance populations of species that are of conservation concern.LAY SUMMARYSimulating the presence of terrestrial birds often attracts breeders of the same species, though how this varies among species, simulated cues, or locations remains unknown.We reviewed 31 experiments that examined conspecific attraction to simulated social cues in terrestrial breeding birds and tested the effects of 19 variables on attraction.These experiments, which focused primarily on migratory songbirds, revealed strong effects of simulated presence on settlement rates, but no strong evidence that any other variables affected settlement rate.Simulating social cues such as vocalizations could be useful for managers interested in attracting migratory songbirds, although whether this extends to other terrestrial species remains unknown.A greater understanding of how and where to use this technique will improve its utility as a tool for enhancing populations of species of conservation concern.

Many plants have evolved floral traits that, in effect, filter pollinator communities and promote pollination by efficient pollinators. Most documented pollinator filter traits act to deter or reduce visitation rates by a subsect of the community of floral visitors. However, a recently described pollinator filter termed ‘pollinator recognition’ (PR) acts at a stage after a pollinator visit. PR was first documented experimentally in Heliconia tortuosa whereby pollen tube germination – a proxy for reproduction – was enhanced following visits from morphologically specialized pollinators, but not generalists. This is thought to promote outcrossing among plants by preferentially investing in reproduction following visits by long-ranging hummingbirds with specialized bill shapes. To date, this plant behavior has only been described in H. tortuosa, but, if widespread, could have important ecological implications; given declines in abundances of specialist pollinators, visits by generalists would not buffer the loss of pollination services to plants with PR. We therefore tested for PR in four taxa spread widely across the Heliconiaceae.We corroborated previous results that visits by long-billed, but not short-billed hummingbirds increased pollen tubes in H. tortuosa with aviary experiments that standardized pollen quality and minimized variation in pollen quantity. Across species, we found great variation in pollen tube responses to experimental treatments. For one species (H. rostrata), we found increased numbers of pollen tubes in those visited by hummingbirds compared to hand pollination alone, regardless of the visiting bird’s bill morphology, indicating recognition of hummingbirds in general. In other cases, hummingbird visits decreased pollen tube counts compared to hand pollinations alone. Furthermore, our results could not substantiate any specific mechanism for pollinator recognition and highlight the need for further work on the complexities of and variability in reproductive strategies across plant taxa.

Habitat selection decisions can impact individual fitness and ultimately scale up to mediate population dynamics. Understanding how birds select habitat is thus critical for discerning the biological processes structuring populations and for developing conservation strategies, particularly for species in decline. Marbled Murrelet (Brachyramphus marmoratus; hereafter murrelet) populations have declined in recent decades due to loss of late-successional forest nesting habitat and changing ocean conditions that impact foraging success. Most other seabirds in the family Alcidae nest colonially and evidence suggests nesting murrelets may aggregate in stands, yet no studies have examined murrelet use of social information in nest-site selection. In 2016, we experimentally simulated the presence of murrelets at 14 randomly chosen potential breeding sites by broadcasting murrelet calls throughout the breeding period. Between broadcasting bouts, we recorded calls of wild murrelets and compared call rates with those recorded at 14 control sites (no broadcast). One year after playbacks ceased (2017) we conducted breeding season surveys to document behaviors indicative of murrelet breeding activity. Broadcasting murrelet calls in 2016 increased daily odds of wild murrelets vocalizing during the treatment period by up to 15.4× (95% CI: 2.3, 125.4) relative to control sites. During the 2017 breeding season, the odds of occupancy were 10.0× (CI: 1.2, 81.4) greater at treatment sites than control sites. These results indicate that social information influences murrelet breeding site selection because the simulated conspecific presence in potential nesting habitat appeared to attract prospectors in 2016 that continued occupying treatment sites the following year. This conspecific attraction implies murrelet nesting sites are likely to remain occupied over time and that large tracts of nesting habitat may be important for supporting murrelet populations. Murrelets may also be susceptible to information-mediated Allee effects whereby a lack of conspecific information about nesting habitat could exacerbate long-term population declines.

Population declines in terrestrial bird species have been reported across temperate regions in the world and are attributed to habitat loss, climate change, or other direct mortality sources. North American and European studies indicate that long-distance migrants, common species, and species associated with grasslands and agricultural lands are declining at the greatest rates. However, data from East Asia on avian population trends and associated drivers are extremely sparse. We modeled changes in occupancy of 52 common breeding landbird species in South Korea between 1997–2005 and 2013–2019. Thirty-eight percent of the species showed evidence of declines, and seven of these were declining severely (46–95%). Occupancy of Black-capped Kingfisher (Halcyon pileata) populations have dropped the most precipitously over the study period. Among declining species, long-distance migrants (9/20) and common species (14/20) showed more rapid declines than other groups. Declines of five species were associated with climate change, and two species appeared to be affected by land-cover change. However, causes of change in occupancy of other species (46/52) remains cryptic. Based on our results, we suggest an immediate re-evaluation of species’ conservation status and legal protection levels for seven severely declining species in South Korea, and a dedicated survey design and analysis effort for the continued monitoring landbird populations. Because many species exhibiting declines migrate from beyond national boundaries, international collaborations will be required to better quantify population trends across the full annual cycle, and to understand mechanisms for these declines.

Forest loss and degradation are the greatest threats to biodiversity worldwide. Rising global wood demand threatens further damage to remaining native forests. Contrasting solutions across a continuum of options have been proposed, yet which of these offers most promise remains unresolved. Expansion of high-yielding tree plantations could free up forest land for conservation provided this is implemented in tandem with stronger policies for conserving native forests. Because plantations and other intensively managed forests often support far less biodiversity than native forests, a second approach argues for widespread adoption of extensive management, or ‘ecological forestry’, which better simulates natural forest structure and disturbance regimes – albeit with compromised wood yields and hence a need to harvest over a larger area. A third, hybrid suggestion involves ‘Triad’ zoning where the landscape is divided into three sorts of management (reserve, ecological/extensive management, and intensive plantation). Progress towards resolving which of these approaches holds the most promise has been hampered by the absence of a conceptual framework and of sufficient empirical data formally to identify the most appropriate landscape-scale proportions of reserves, extensive, and intensive management to minimize biodiversity impacts while meeting a given level of demand for wood. In this review, we argue that this central challenge for sustainable forestry is analogous to that facing food-production systems, and that the land sharing–sparing framework devised to establish which approach to farming could meet food demand at least cost to wild species can be readily adapted to assess contrasting forest management regimes. We develop this argument in four ways: (i) we set out the relevance of the sharing–sparing framework for forestry and explore the degree to which concepts from agriculture can translate to a forest management context; (ii) we make design recommendations for empirical research on sustainable forestry to enable application of the sharing–sparing framework; (iii) we present overarching hypotheses which such studies could test; and (iv) we discuss potential pitfalls and opportunities in conceptualizing landscape management through a sharing–sparing lens. The framework we propose will enable forest managers worldwide to assess trade-offs directly between conservation and wood production and to determine the mix of management approaches that best balances these (and other) competing objectives. The results will inform ecologically sustainable forest policy and management, reduce risks of local and global extinctions from forestry, and potentially improve a valuable sector's social license to operate.

Research hypotheses have been a cornerstone of science since before Galileo. Many have argued that inclusion of multiple hypotheses (1) encourage discovery of mechanisms, and (2) reduce bias – both features that should increase transferability and reproducibility. However, we are entering a new era of big data and highly predictive models where some argue the hypothesis is outmoded. Indeed, using a detailed literature analysis, we found prevalence of hypotheses in eco-evo research is very low (6.7-26%) and static from 1990-2015, a pattern mirrored in an extensive literature search (N=302,558 articles). Our literature review also indicates that neither grant success or citation rates were related to the inclusion of hypotheses, which may provide disincentive for hypothesis formulation. Here we confront common justifications for avoiding hypotheses and present new arguments based on benefits to the individual. Although hypotheses are not always necessary, we expect their continued and increased use will help our fields move toward greater understanding, reproducibility, prediction, and effective conservation of nature.

The effective conservation of birds requires knowledge of species-specific population dynamics. Yet these dynamics during migration and across age and sex categories are poorly understood for small birds. The goal of this study was to assess large-scale fall migration patterns of Rufous Hummingbirds (Selasphorus rufus). Because the age and sex categories of this species depart from the breeding grounds and arrive from migration on different weeks, we predicted that each might use different migration routes, differ in migration speeds, and vary in their weekly distributions. Rufous Hummingbirds are among a few declining species for which a large amount of banding data is available during migration and across the migration corridor. We assembled a large hummingbird capture dataset (28,948 captures; 459 unique locations; fall migrations from 1998 to 2013) and used the centroid location of each age-sex-year-week group to calculate migration routes, timing, and speed. We used a utilization distribution kernel to measure distributions during migration. Adult females tended to have a southbound migration route parallel and between those of young and adult males. Moreover, a greater number of young birds migrated south through California in comparison to adult females and adult males. Our results suggest that the migration of each age-sex category is separated by approximately two weeks with adult males migrating first, followed by adult females, and then the young of both sexes; yet migration speed was not statistically different among categories. Last, adult males were captured within a smaller geographic distribution, i.e., the area during any given week of migration, compared with adult females and young. We conclude that different age-sex categories of Rufous Hummingbirds use alternative routes and differ in migration phenology and distributions. Our results suggest that the age-sex categories could be affected differentially by habitat loss, phenological changes, and climates during migration. Considering such demographic migratory dynamics could improve conservation outcomes.

Theory predicts that species requiring multiple habitat types simultaneously should have heightened sensitivity to anthropogenic pressures, yet tests of this prediction are especially rare. We tested whether breeding site occupancy of the threatened marbled murrelet (Brachyramphus marmoratus) was driven by the synergistic effects of nesting habitat loss in forests, and changing ocean conditions. We paired 70,700 murrelet surveys at 19,837 sites across 20 years from the Oregon Coast Range with annual data on the extent of old forest and biophysical ocean conditions. Dynamic occupancy models indicated that local murrelet colonization rates were strongly reduced during warm ocean conditions with low prey availability. Landscapes that contained more old forest and were closer to the ocean showed reduced rates of local extinction. Given predictions of accelerated ocean warming and increased global timber demand, our results suggest murrelets may continue to be imperiled by deterioration of the two habitats upon which they depend.

By regulating populations of herbivores, predators can indirectly influence plant production. However, the factors influencing the strength of this type of trophic cascade are still unclear. We hypothesized that changes to plant community structure would affect the number of avian predators, thereby mediating cascade strength. Using a 4-yr, blocked, split-plot experiment, we independently manipulated both predators (birds) and plants in an early seral managed forest system in western Oregon, USA, and measured abundance across three trophic levels. We applied herbicides, as a surrogate for land-use intensification, to recently clear-cut stands to establish an experimental gradient in plant abundance and species richness, and excluded birds using 28, 225 m2 exclosures. In total, we counted and identified 94,738 arthropods of 141 families in paired control and bird exclosure plots. On average, insectivorous birds reduced arthropod abundance by 16% and plant damage by 14%, and some well-known pests (e.g., Adelges cooleyi) of crop trees (mostly Pseudotsuga menziesii) in our system were reduced by as much as 30%. However, this effect did not translate into a trophic cascade that increased crop-tree growth in the presence of birds. We experimentally reduced plant abundance and diversity by 67% and 55%, respectively, in the most intensive herbicide treatment in relation to untreated controls, but reduced vegetative resources did not change the strength of the direct effect of birds on arthropods or the indirect effect of birds on plants.