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Hummingbirds represent an avian family restricted to the Americas that feeds mainly on nectar obtained from ornithophilous plants. In North America (Mexico-USA-Canada), 58 species have been reported out of the 330 total hummingbird species, all of them occurring in Mexico. In this work we analyzed the distribution of hummingbirds in relation to the coverage of the natural protected area system in Mexico using a complementarity analysis to assess the minimum set of areas needed to protect all species. We focused our search mainly to biosphere reserves, as these areas have complete bird lists. Six biosphere reserves included 93% of the hummingbird species. Four species were not included in any biosphere reserve or other natural protected area. To preserve those species, three important bird areas (AICAs as they are known in Spanish) are needed. With these nine areas, all hummingbird species are included. Hummingbird distributions can be classified in six groups that distribute following the major biogeographic regions described for Mexico, including groups using; (1) the main mountain ranges, (2) the Pacific tropical dry forests, (3) the Gulf of Mexico slopes with tropical dry forest, (4) the humid tropical forest in southern Mexico, and both (5) Yucatan and (6) Baja California peninsulas.
Healthy plant communities of the American sagebrush steppe consist of mostly wind-pollinated shrubs and grasses interspersed with a diverse mix of mostly spring-blooming, herbaceous perennial wildflowers. Native, nonsocial bees are their common floral visitors, but their floral associations and abundances are poorly known. Extrapolating from the few available pollination studies, bees are the primary pollinators needed for seed production. Bees, therefore, will underpin the success of ambitious seeding efforts to restore native forbs to impoverished sagebrush steppe communities following vast wildfires. This study quantitatively characterized the floral guilds of 17 prevalent wildflower species of the Great Basin that are, or could be, available for restoration seed mixes. More than 3800 bees representing >170 species were sampled from >35,000 plants. Species of Osmia, Andrena, Bombus, Eucera, Halictus, and Lasioglossum bees prevailed. The most thoroughly collected floral guilds, at Balsamorhiza sagittata and Astragalus filipes, comprised 76 and 85 native bee species, respectively. Pollen-specialists dominated guilds at Lomatium dissectum, Penstemon speciosus, and several congenerics. In contrast, the two native wildflowers used most often in sagebrush steppe seeding mixes—Achillea millefolium and Linum lewisii—attracted the fewest bees, most of them unimportant in the other floral guilds. Successfully seeding more of the other wildflowers studied here would greatly improve degraded sagebrush steppe for its diverse native bee communities.
Animal-pollinated plants depend on sequential pollinator visits to conspecifics for successful reproduction. Therefore, in co-flowering plant communities, the proportion of visits to a focal plant species in individual pollinator foraging bouts determines reproductive outcomes for that species. We investigated the factors determining bee visits to the plant Astragalus scaphoides within foraging bouts in a natural multispecies community in the northern Rocky Mountains. We found that both conspecific and heterospecific floral density influenced the proportion of visits to A. scaphoides during foraging bouts, but these effects of floral density differed among two abundant bee groups. Our field observations reject the null expectation that bees visit plant species in direct proportion to their relative floral densities. Bombus consistently visited A. scaphoides more than expected, while solitary bees of the genera Anthophora and Eucera exhibited a nonlinear response to floral density.
Habitat restoration is considered critical for maintaining and restoring biodiversity of many species groups. A better understanding of how species respond to the restoration process is imperative to identifying practices that benefit the target organisms. Using survey responses from land managers about the restoration process in tallgrass prairie habitat, we identify common restoration and management techniques. These responses are then combined with current literature on bee and plant responses to these methods in tallgrass prairie habitat. While some widely used methods, such as burning, are believed to be fairly benign to bees, there are still many knowledge gaps about how bees may respond to many common practices such as tillage, pesticides, and grazing in tallgrass prairie. Other commonly used methods, such as broadcasting of seeds, are known to significantly affect plant diversity, which could hinder bee conservation efforts. The variability in bee and plant response to commonly used methods highlights why it is necessary to better understand how management methods affect plant and bee communities.
The effective conservation management of declining pollinators requires evidence-based policy and planning. In Ontario, Canada, pollinator-relevant policy and management plans are currently being developed by various ministries with diverse mandates. This review gathers relevant scientific findings to help guide policy decisions and implementation, focusing on the available information for wild bumble bees. Species that occur in Ontario also occur elsewhere in Canada and the United States. Thus, relevant studies from other jurisdictions are also included if they consider species that occur in Ontario. Evidence for declines, review of known and suspected threats, and management recommendations based on this information are presented.
Bees and butterflies generally favor open forest habitats regardless of forest type, geographic region, or methods used to create these habitats. Dense shrub layers of native or nonnative species beneath forest canopies negatively impact herbaceous plant cover and diversity, and pollinators. The presence of nonnative flowers as a source of nectar, pollen, or larval food can have positive or negative effects on pollinators depending on the situation, but in cases where the nonnatives exclude native plants, the results are almost always negative. Roads and roadside corridors offer an opportunity to increase open, pollinator-friendly habitat even in dense forests by thinning the adjacent forest, mowing at appropriate times, and converting to native herbaceous plant communities where nonnative species have been planted or have invaded. Efforts to improve forest conditions for pollinators should consider the needs of specialist species and vulnerable species with small scattered populations. Conservation of bees and butterflies, as well as other pollinating species, in forested areas is important for most forest plant species, and forests may serve as reservoirs of pollinators for recolonization of surrounding habitats.
Pollinators, such as butterflies, contribute to vital ecosystem services, but are susceptible to changing thermal regimes associated with recent climate change. While butterflies are responding to climate changes in many ways, they are not keeping pace. Rapid climate changes are leading to an accumulation of climate debts (or loss of climatic habitat) at continental scales. Climate change mediated shifts in distribution depend on many factors, but particularly on species-specific dispersal abilities and availability of larval host plants. We measured geographical variation in mobility for butterfly species across North America relative to their conservation status and the intensity of human land use. We identified areas where the rate and variability of recent climatic changes have been relatively low and could be managed for pollinator conservation, potentially augmenting existing protected area networks. Using the Yellowstone to Yukon region as a case study, we outline differences between connectivity analyses that incorporate (i) human footprint, (ii) human footprint in conjunction with climate change considerations, and (iii) human footprint in conjunction with climate change considerations weighted by species mobility and richness. All three approaches yield different connectivity recommendations. Conservation management efforts to enhance climate change-related dispersal should focus on improving landscape connectivity based on species-specific mobility, richness, and climate change, as well as landscape permeability. Improving connectivity is particularly vital in areas where mobility and landscape permeability are low but species are at greatest risk of extinction. Mobility matters when considering efforts to mitigate climate change impacts on butterflies.
The 56 US State Wildlife Action Plans provide strategic guidance and direction for the state, territorial, and federal wildlife and natural resource management agencies in the United States. Funding associated with these plans supports a broad spectrum of state wildlife diversity and nongame programs, state natural heritage programs, and state natural areas programs. The implementation of these plans is being coordinated by the state and territorial fish and wildlife agencies, which have legal management authority for much of the native pollinator diversity in the United States. Forty of the 56 plans published in 2005 included taxa from one or more pollinator groups, including representatives of the insect orders Lepidoptera, Hymenoptera, and Diptera (Insecta), as well as nectar-feeding bats and hummingbirds. We document specific examples of pollinator conservation projects that have been conducted by state fish and wildlife agencies between 2005 and 2015 in order to achieve conservation objectives identified in the State Wildlife Action Plans. Comprehensive revisions of these plans, completed in 2015 and now under review by the US Fish and Wildlife Service for final approval, will include significant increases in coverage of pollinator taxa. Based on our surveys of state wildlife planners in May and June 2015, we document increases in the number of states that are including moths, nectar-feeding bats, bumble bees, and other native bees in their revised plans. The increased coverage of pollinator taxa in these plans will generate additional opportunities for pollinator conservation for the state agencies and their partners
Many federal, state, and tribal agencies, as well as nonprofit organizations, have recently increased efforts to understand how natural areas can be managed to enhance native pollinators and the ecosystem services they provide. However, managing this important group must be balanced with other services that natural areas provide including hunting, timber production, and livestock grazing. Significant knowledge gaps exist about how to effectively manage habitats used by large ungulates (e.g., cattle (Bos taurus), elk (Cervus elaphus), mule deer (Odocoileus hemionus)) in ways that also enhance pollinators. One key gap is understanding the degree to which diets of mammalian herbivores overlap with floral resources used by bees, and how this overlap varies spatially and temporally. Invertebrate pollinators, including bees, rely on flowering forbs and shrubs for nectar and pollen. Ungulates also feed on flowering plants, although preferences vary by ungulate species, vegetation community, and season. Here we review existing literature on ungulate diets relative to flowering plants and compare this information with flower preferences of bees, drawing on studies of bee abundance and diversity at the Starkey Experimental Forest and Range in northeastern Oregon. Our review can inform managers about the potential dietary overlap between ungulates and native bees and aid planning efforts aimed at biodiversity conservation of pollinators. We discuss management implications relative to seasonal habitat use and dietary preferences of ungulates and variation in bee phenology, and conclude with guidance about timing and intensity of ungulate grazing when managing for multiple conservation objectives, especially in sensitive habitats like riparian areas.
The western or European honey bee (Apis mellifera) is the primary managed pollinator in US agricultural systems, and its importance for food production is widely recognized. However, the role of A. mellifera as an introduced species in natural areas is potentially more complicated. The impact of A. mellifera on native insect pollinators can depend on broad community context, as can the relative effectiveness of A. mellifera in pollination of both native and nonnative plant species outside of agricultural systems. Apis mellifera is highly generalist and able to interact with hundreds of native plant species following its naturalization. It is unlikely to wholly replace native pollinators as visitors of specialized plant species, and its behavioral characteristics tend to reduce A. mellifera's per-visit efficiency, even when its overall effectiveness is high. Preliminary results of our case study exploring the importance of A. mellifera vs. native bees as pollinators of native plants in Hawai‘i indicate that A. mellifera is less important than native Hylaeus bees as a flower visitor of focal native plant species. In light of current global declines in A. mellifera populations, maintenance of a diversity of pollinators and pollinator habitat are critical conservation needs in natural areas.
The steep declines over the last quarter century of wild pollinators in the Southwest among native bees, monarch butterflies (Danaus plexippus L.), hummingbirds, and nectar-feeding bats have come during a time of accelerated climate change, and are likely due to a variety of stresses interacting with climatic shifts. Nevertheless, there is mounting evidence that declining availability and altered timing of floral resources along “nectar corridors” accessible to pollinators involves climatic shifts as a serious stressor that had been previously underestimated. Longitudinal studies from both urban heat islands and rural habitats in Southwestern North America suggest peak flowering of many wildflowers serving as floral resources for pollinators is occurring three to five weeks earlier in spring than a century ago, leaving “phenological gaps” in nectar resource availability for certain pollinators. To avoid the threat of what A. Dobson (Professor of Ecology and Evolutionary Biology, Princeton University) and others have termed “food web collapse,” a range of groups have initiated ecological restoration efforts in semi-arid zones that attempt to (a) assemble more resilient plant-pollinator food chains, and (b) hydrologically restore watercourses to ensure water scarcity will be less likely to disrupt re-assembled food chains in the face of droughts, catastrophic floods, and other correlates of global climate change. We recommend “bottom-up food chain restoration” strategies for restoring nectar corridors in protected areas on or near geopolitical and land management boundaries in all regions, but particularly in the Southwest or US-Mexico desert border states. We highlight binational and multicultural workshops facilitated to communicate about, and initiate restoration of, mutualistic relationships among plants, pollinators, and people to protected area managers on both sides of the border.
Monarch butterflies (Danaus plexippus), other pollinators, and Greater Sage-Grouse (Centrocercus urophasianus) are currently the focus of increased conservation efforts. Federal attention on these fauna is encouraging land managers to develop conservation strategies, often without corresponding financial resources. This could foster a myopic approach when allocating resources and setting restoration priorities, and at best, allow for inefficiencies in the usage of land management resources, or, at worst, pit one species (or suite of species, e.g., pollinators) against another (e.g., sage-grouse). Instead, investing holistically by linking conservation of these fauna may provide improved leverage of available resources and more benefit to the landscape. Fortunately, on the western US rangelands, these fauna can all benefit from restoration that increases the abundance and diversity of forbs. Establishing high density islands of outplanted forb seedlings may be a way to expedite restoration. Managers establishing forbs for pollinators (including monarchs) would further increase food availability for greater sage-grouse and vice versa. Adding milkweeds (Asclepias spp.) in appropriate areas to forb mixtures for restoration is warranted because they are excellent nectar sources for pollinators in general and the sole host for monarch larvae in particular. Here, we provide an overview of why forb species are keystone for monarch butterflies, other pollinators, and Greater Sage-Grouse and how seeding and outplanting seedlings of specific forbs are critical to restoration efforts.
Restoration practices that enhance pollinator habitat can improve conservation outcomes, including support of pollinator-dependent plant species. Yet, limited background research has assessed the benefits of incorporating greater native forb diversity into larger-scale restoration operations to justify the often increased costs of pollinator seed mixes. This study examined changes in pollination services received by Santa Susana tarweed, Deinandra minthornii, a California-listed Rare (CR) endemic of the Santa Susana Mountains that were associated with a native forb seed mix used in a large-scale remediation program at the Santa Susana Field Lab (SSFL) in Los Angeles, California. A four-year study of pollinator community dynamics and services was conducted from 2011 to 2014 examining aggregations of D. minthornii near to and farther from restoration activities. We hypothesized that D. minthornii located closer to the areas seeded with the forb mixes would be visited by more pollinators and receive greater pollination services, resulting in increased seed viability. Pollinator exclusion experiments indicate D. minthornii to be highly dependent on pollinators for seed set (excluded seed viability = 4.1% ± 7.4; open viability = 65.5% ± 19.5). Populations located closer to pollinator-specific restoration seedings were visited by more bees and more bee types (P = 0.00), and showed a 30% higher seed viability when compared to populations located in unrestored areas (mean seed viability near = 62.20% ± 18.6, far = 48.00% ± 11.7). We encourage the use of regionally appropriate forb seed mixes in remediation scenarios to enhance pollination services.
The genus Agave is one of the most diverse and rich groups of plants of Mexico. Mexican people have developed several technologies to extract products from Agave, and for many years they have consumed five different alcoholic beverages derived from Agave: Tequila, Mezcal, Bacanora, Raicilla, and Pulque. Additionally, Agave has coevolved with nectar-feeding bats, and in several cases, bats play the main role as functional pollinators in this ecological relationship. But with growth in the demand of agave derived products, management practices have reduced dependence on bat pollination, using instead clonal shoots to replant fields and harvesting plants before flowering, thereby negatively affecting both bats (by decreasing food availability) and agaves (by lowering their genetic diversity). We explore the possibility that bat-friendly practices may be incorporated into the production system. We compiled data about the pollination biology of Agave to infer how many bats could use the available resources, if Mezcal and Tequila producers allowed 5–10% of agave crop inflorescences to flower based on a linear projection using Agave angustifolia (a sister group of A. tequilana). If only 5% of the plants in one hectare were allowed to flower (approximately 222 individuals), then, depending on nectar concentration and total volume, a minimum of 89 individual bats could feed every night during flowering period. This means that allowing 5% of the current total population of A. tequilana reproductive agaves to flower could feed a total of 2,336,250 nectar feeding bats per month.
Restoration projects that support pollinators are becoming increasingly popular. Pollinating insects require resources, including nectar and pollen, throughout the growing season. However, commercially available seed mixes vary considerably in their phenological diversity, as well as in the diversity of species and plant families included, and in their forb:grass ratio (by seed count). Each of these is important for the support of a diverse pollinator community. We examined several commercial mixes to determine if they met our criteria for optimal pollinator support. Most mixes did not contain many, if any, species that bloom in the spring. Suggestions on additional plant species to include in upper Midwest pollinator restorations seed mixes to extend the season of bloom are provided. Although our recommendations are regionally focused, these principles could be extended to any plant community.
The article entitled, “Compassionate Conservation for Yellowstone's Wolves,” written by Tony Povilitis and published in the July 2016 edition of The Natural Areas Journal 36(3):334–338, experienced a problem that resulted in a small amount of unreadable text within the article and a portion of data in Table 1. Corrected images of Table 1 have been posted on our BioOne website and we sincerely regret any inconvenience this may have caused.
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