Habitat Availability Research Articles

Facets of functional diversity support niche‐based explanations for Australian biodiversity gradients

AbstractAimThere is widespread support that species richness increases with the available energy of an ecosystem, but the mechanisms underlying this driver of biodiversity patterns remain elusive. We evaluated gradients of functional diversity to test whether the higher species richness of productive, structurally diverse environments is due to a greater range of niches being supported by the abiotic conditions present (environmental filtering), greater availability of biotic resource and habitat niches (more niches) or increasing functional similarity of species (niche packing).LocationAustralia.TaxonBirds and mammals.MethodsWe used structural equation modelling to evaluate the relative contributions of climatic harshness (actual evapotranspiration, AET) and the availability of resource (gross primary productivity, GPP) and habitat (tree height) niches on taxonomic richness and functional richness, dispersion and evenness. We performed parallel analyses within 15 bioclimatic zones and continentally to evaluate the scaling of biodiversity gradients and the shifting balance between niche‐based mechanisms along environmental gradients.ResultsAll continental diversity gradients were primarily associated with energy variables, but while species richness of both taxa and all functional diversity measures of bird assemblages increased with AET, mammal functional diversity was more strongly associated with GPP gradients. Results were more variable at the regional scale, but species richness gradients along tree height (birds and mammals) and GPP (mammals) within bioclimatic zones tended not to be paralleled by increases in functional richness or dispersion.Main ConclusionsThe niche‐based explanations of biodiversity gradients varied in importance with scale, position on environmental gradients and taxonomic group. At the continental extent, bird biodiversity gradients were structured by environmental filtering by climatic harshness, while mammal biodiversity was related to the increasing availability of resource niches with increasing productivity. Niche packing was more prominent at the regional scale, especially in bioclimatic zones where productivity and vegetation height were less limiting, and in mammal assemblages, suggesting that biodiversity patterns scale differently for birds and mammals.

Seasonal dynamics of Wyeomyia leucostigma Lutz, 1904 (Diptera: Culicidae) in Typha L., 1753 marshes in an urban protected area: use of larval habitats and its relation with environmental variables

Larval habitat availability, Typha phytotelmata use and the relation of environmental factors to annual dynamics of the mosquito Wyeomyia leucostigma Lutz, 1904 (larvae and females) were studied in Costanera Sur Ecological Reserve at Buenos Aires, Argentina. Bimonthly, 1520 plants were examined, detecting W. leucostigma in 80.8% of surveys. Larval habitat availability was associated with temperature, but not with rainfall. In addition, the high temperature was associated with greater biting rate. Dynamics of host-seeking were recorded over 10 months of the year and were associated with temperature as well. Furthermore, an accidental fire led to an increase of W. leucostigma abundance likely based on an increase of the Thypha marshes productivity that occurred after the fire.

The influence of freshwater inflow and seascape context on occurrence of juvenile spotted seatrout Cynoscion nebulosus across a temperate estuary.

Spotted seatrout, a popular recreational sport fish in the southeastern United States, are affected by freshwater flow conditions and the availability of estuarine habitat. However, the relative influence of these factors, particularly on early life stages of seatrout, remains uncertain. We used generalized linear models to quantify relationships between the probability of encountering juvenile spotted seatrout during seine surveys and various factors, including freshwater inflow conditions, the availability and richness of estuarine habitats (seagrass, salt marsh, oyster beds) around (400-m radius) fish collection sites (seascape-scale context), as well as distance to the nearest inlet to the Gulf of Mexico (estuary-scale context) across shallow waters (< 1.5 m depth) of Apalachicola Bay, Florida. Modelling results showed a consistent positive correlation between seagrass area and the probability of encountering juvenile seatrout (all four size classes from 15mm-200mm Standard Length (SL)). The probability of encountering the two smallest juvenile seatrout size classes (15-50mm and 51-100mm SL) was also related to freshwater inflow conditions, particularly within a 3-month period prior to and including peak recruitment. Freshwater inflow may affect early life stages by influencing passive transport of eggs and larvae, planktonic food availability, and predation pressure through increases in turbidity. In contrast, encounter probabilities of the two larger size classes (101-150mm and 151-200mm) were unrelated to freshwater inflow. Inflow-related processes may be less important to the larger juveniles as they have typically settled out of the plankton into benthic habitats which provide refuge from predation and abundant benthic food sources which are not as closely tied to freshwater inflow effects. In addition, models revealed that occurrence of the larger juveniles was related to the availability of nearby habitat types such as oyster beds and salt marshes, suggesting that increased mobility as seatrout grow may allow them to use nearby habitat types as additional sources of food and refuge. These results add to a growing body of literature aimed at understanding the influence of freshwater inflow as well as seascape context on vulnerable juvenile life stages of fishery species to provide more informed strategies for freshwater inflow management and habitat conservation.

Optimizing Water Level Management Strategies to Strengthen Reservoir Support for Bird’s Migration Network

Migratory waterbirds depend on a complex network of wetlands globally for their life cycles. However, habitat loss and degradation pose risks to these networks’ sustainability, potentially impacting wetland habitat availability. This study investigates the impact of water level changes in Beijing’s Miyun Reservoir on white-naped cranes’ (Antigone vipio) habitat use. We utilized satellite imagery from 2000–2021 and monthly data from 2018–2023 to observe changes in the reservoir’s water and land areas. Additionally, the study tracked 32 cranes using GSM-GPS loggers, yielding insights into their movement patterns and habitat preferences. Our findings emphasize the significant influence of reservoir water levels on habitat availability for these cranes. Notably, our results indicate that the decrease in suitable migratory bird habitats in the reservoir is primarily attributed to high-water level management strategies. This study highlights the necessity for balanced management of aquatic and terrestrial areas in reservoir ecosystems to preserve migratory waterbird habitats.

Identifying New England’s underutilized seafood species and evaluating their market potential in a changing climate

Developing and diversifying market opportunities for lesser known yet abundant seafood species has been a successful strategy for seafood businesses in the Northeast United States. Since climate change and other stressors are currently threatening the economic vitality of New England’s seafood industry, it is important to identify if there are lesser-known species that could simultaneously support additional market opportunities and remain resilient in a warming climate. We developed a quantitative definition for the term “underutilized species’’ based on five criteria derived from science-based sustainable fishing metrics. Using this definition, we evaluated 47 stocks in the Northeast United States during the initial time period of 2013-2017 to identify seven underutilized finfish species that could be considered for new market opportunities as part of a climate-smart approach: 1) Acadian redfish (Sebastes fasciatus), 2) Atlantic pollock (Pollachius virens), 3) butterfish (Peprilus triacanthus), 4) haddock (Melanogrammus aeglefinus), 5) scup (Stenotomus chrysops), 6) silver hake (Merluccius bilinearis), and 7) white hake (Urophycis tenuis). The climate resiliency of these resulting seven species was then evaluated using a framework consisting of species-specific metrics on climate sensitivity, directionality (of responses to climate impacts) and future habitat availability under warming scenarios. Our results show that assessing underutilized species on a regular basis and evaluating their ongoing responses to climate change can be a part of a climate-smart approach towards building more diversified and adaptive markets.

Environmental determinants of aquatic plant diversity differ between growth forms and range sizes

Aquatic plants are fundamental for aquatic ecosystems. Understanding variations in geographic patterns of aquatic plant diversity across growth forms is important for conservation and restoration of aquatic ecosystems. Environmental drivers, including climate, climate heterogeneity, water chemistry, habitat availability and geodiversity, could influence aquatic plant diversity and species composition across communities, yet their relative impacts remain controversial. Here, we examined geographic patterns and drivers of species richness of Chinese aquatic plants with different growth forms. We compiled distributions of 656 aquatic plant species in China at 50 × 50 km2 resolutions, and estimated richness patterns for species with different growth forms (i.e., helophyte, emergent, floating-leaved, free-drifting and submerged) and range sizes. Hierarchical partitioning analysis was employed to evaluate the independent effects of different environmental drivers on species richness. The Sørensen dissimilarity index and Multiple Matrix Regression with Randomization were used to compare the relative effects of environment and dispersal limitation on species dissimilarity between grid cells. Overall species richness was highest in northeastern and southern China, although species richness patterns varied across growth forms. Among environmental drivers examined, climate was the key determinant of the species richness of helophyte, emergent, floating-leaved and free-drifting plants, while habitat availability and water chemistry best explained the richness of submerged species. The richness of narrow-ranged species was dominated by climate, while the strongest determinant of wide-ranged species richness varied across growth forms. Our study mapped the species richness patterns of aquatic plants in China and indicated that the relationship between aquatic plant richness and environment significantly differed between growth forms and between wide-ranged and narrow-ranged species. These findings indicate the necessity of distinguishing growth forms in studies related to aquatic plants, and suggest that future climate change might threaten the distribution of narrow-ranged aquatic plants.

A new set of metrics and framework to assess the colonization potential of riverscapes by wind-dispersed plant species

Quantifying the potential of a braided riverscape to be colonized by a plant species is essential for assessing the ecological state of the river and provides an important basis for nature conservation planning and the implementation of restoration measures. Common connectivity indices are largely unsuitable for describing the situation for the mostly wind-dispersed plant species. Our approach provides a set of comparable metrics that allows the quantification of the colonization potential of riverscapes at the patch and riverscape level. We propose a set of cell-based, spatially explicit measures that can easily be implemented. We demonstrate their application using two typical plant species and three riverscapes with different habitat configurations as examples. Our metrics consider shape, size and the spatial configuration of habitat patches, along with the dispersal characteristics of the respective species. The metrics provide a linear, balanced, and realistic representation of the colonization potential at the cell, patch, and riverscape levels. The results are comparable between different riverscapes and species, can be easily extended and used for further modeling. The metrics provide a valuable tool for the planning and evaluation of conservation, restoration, and reintroduction measures and close the gap between habitat availability analyses and large-scale terrestrial connectivity indices.

Anopheles larval habitats seasonality and environmental factors affecting larval abundance and distribution in Arjo-Didessa sugar cane plantation, Ethiopia

BackgroundWater resource development projects are essential for increasing agricultural productivity and ensuring food security. However, these activities require the modification of pre-existing environmental settings, which may alter mosquito larval habitat availability and seasonality. The intensive utilization of current adult vector control tools results in insecticide resistance among the main vectors. When coupled with behavioural resistances, a shift in malaria vector feeding and resting behaviours could compromise the effectiveness of the current adult vector control strategies. Thus, it is important to look for new or alternative vector control interventions for immatures to complement adult control by focusing on different larval habitats and their seasonal availability. Thus, this study investigated larval habitat seasonality and seasonal larval abundance and distribution in irrigated sugar cane plantation settings in Ethiopia.MethodsAnopheles mosquito larval habitats were surveyed and visited twice a month for a period of 14 months. Anopheline larvae and pupae were collected, reared, and fed finely ground fish food. Adults were provided with sucrose solution and kept under standard conditions. Female Anopheles mosquitoes were identified morphologically and using a species-specific PCR assay. Environmental parameters, which include habitats’ physico-chemical characteristics, were assessed. Larval habitat diversity and larval abundance and distribution were determined across different seasons.ResultsThe study revealed that Anopheles gambiae sensu lato (s.l.) was the most predominant 4197(57%) vector species, followed by Anopheles coustani complex 2388 (32.8%). Molecular analysis of sub-samples of An. gambiae s.l. resulted in Anopheles arabiensis (77.9%) and Anopheles amharicus (21.5%), and the remaining 1.1% (n = 7) sub-samples were not amplified. Physico-chemical parameters such as temperature (t = 2.22, p = 0.028), conductivity (t = 3.21, p = 0.002), dissolved oxygen (t = 7.96, p = 0.001), nitrate ion (t = 2.51, p = 0.013), and ammonium ion (t = 2.26, p = 0.025) showed a significant and direct association with mosquito larval abundance. Furthermore, mosquito larval abundance was correlated with distance to the nearest houses (r = − 0.42, p = 0.001), exposure to sunlight (r = 0.34, p = 0.001), during long and short rainy season animal hoof prints, truck tires/road puddles and rain pools were negatively correlated (r = − 0.22, p = 0.01) and types of habitat (r = − 0.20, p = 0.01). Significant habitat type productivity were observed in man-made pools (t = 3.881, P = 0.01163), rain pools, animal hoof prints, (t = − 4.332, P = 0.00749 in both short and long rainy season, whereas, during dry seasons habitat type productivity almost similar and have no significance difference.ConclusionThe study found that different larval habitats had variable productivity in different seasons, and that physical and physicochemical features like ammonium and nitrate, as well as the distance between larval habitats and households, are related to larval production. As a result, vector control should take into account the seasonality of Anopheles larval habitat as well as the impact of pesticide application on larval source management.

Variation of CO2 fluxes, net ecosystem production, and calcification in tropical waters of seagrass and coral reef

Carbonate system alteration in Indonesia's seagrass and coral reef ecosystems must be better understood. Changes in CO2 fluxes, ecosystem production, and calcification can impact the availability of resources and habitats for seagrass and coral reef species, which can have cascading effects on the overall health and diversity of marine ecosystems. The study aims to identify diurnal and seasonal CO2 flux, net ecosystem production (NEP), and net ecosystem calcification (NEC) in the tropical waters (Sire Bay, Lombok) around seagrass and coral reef ecosystems. Field sampling was conducted in two seasons and measured the seawater carbonate system and physicochemical characteristics. We found a significant difference in CO2 flux between seagrass and coral reefs in April but not for NEP and NEC in April or October. Both ecosystems act as CO2 sources in April, and CO2 sinks in October. The NEP of coastal water tends to be autotrophic in April and heterotrophic in October. The calcification rate was inversely proportional to the NEP, where the NEC was higher in October than in April. There was a low relationship between CO2 flux and NEP and NEC, indicating that changes in CO2 flux do not directly affect NEP and NEC in Sire Bay waters.

Heterogeneity in habitat and nutrient availability facilitate the co-occurrence of N2 fixation and denitrification across wetland–stream–lake ecotones of Lakes Superior and Huron

Heterogeneity in habitat and nutrient availability facilitate the co-occurrence of N2 fixation and denitrification across wetland–stream–lake ecotones of Lakes Superior and Huron

Incorporating biodiversity responses to land use change scenarios for preventing emerging zoonotic diseases in areas of unknown host-pathogen interactions.

The need to reconcile food production, the safeguarding of nature, and the protection of public health is imperative in a world of continuing global change, particularly in the context of risks of emerging zoonotic disease (EZD). In this paper, we explored potential land use strategies to reduce EZD risks using a landscape approach. We focused on strategies for cases where the dynamics of pathogen transmission among species were poorly known and the ideas of "land-use induced spillover" and "landscape immunity" could be used very broadly. We first modeled three different land-use change scenarios in a region of transition between the Cerrado and the Atlantic Forest biodiversity hotspots. The land-use strategies used to build our scenarios reflected different proportions of native vegetation cover, as a proxy of habitat availability. We then evaluated the effects of the proportion of native vegetation cover on the occupancy probability of a group of mammal species and analyzed how the different land-use scenarios might affect the distribution of species in the landscape and thus the risk of EZD. We demonstrate that these approaches can help identify potential future EZD risks, and can thus be used as decision-making tools by stakeholders, with direct implications for improving both environmental and socio-economic outcomes.

Changes in the Functional Role of the Tejo Estuary (Portugal, Europe) According to Fish Ecological Guilds

Estuaries are extremely productive ecosystems, providing habitats for numerous aquatic species and crucial ecological services. The Tejo estuary, one of the largest European estuaries, has been thoroughly studied, and its important functional role as a nursery for several commercially important fish species is already established. In the present work, a trait-based approach was applied to functionally describe the fish community structure of the Tejo estuary and to enlighten potential changes in the ecosystem functioning at this level, following environmental changes expected to occur. To predict the distribution of species from the two most representative ecological guilds of the Tejo estuary, estuarine residents and marine migrants, species distribution models were built using an ensemble technique (combining forecasts of single models). The predictions obtained were more accurate for the marine migrants and the species distribution was strongly related with salinity, whereas estuarine species, were also influenced by depth, habitat type and river flow. The potential distributions of these ecological guilds showed that marine migrants will tend to use upstream areas in the estuary, where salinity is lower. Nonetheless, salinity is expected to increase as extreme weather events such as droughts tend to occur more frequently, decreasing favorable habitat availability for these species, and thus threatening the crucial role this ecosystem plays for these species.

An acoustic-optic comparison of fish assemblages at a Rigs-to-Reefs habitat and coral reef in the Gulf of Thailand

The number of decommissioned oil and gas platforms will increase over the coming decades. In the tropics and sub-tropics, platforms may operate near biodiverse natural habitats, such as coral reefs. Abundant and diverse fish communities often aggregate around platforms, with different decommissioning options posing variable ecological effects on these assemblages. One decommissioning option is to repurpose platforms into artificial reefs, a process commonly termed “Rigs-To-Reefs” (RTRs). Many RTR programs attempt to retain or enhance habitat availability and associated fish assemblages. To help demonstrate the importance of RTR projects, the fish habitat value of RTRs can be estimated by comparing the fish communities of RTRs to those of adjacent natural habitats. Surveying fish habitats in turbid waters necessitates the use of methods that can quantify the abundance, biomass, and length of fishes irrespective of visibility. Using an imaging sonar (1.2. MHz) and implementing a novel, pixel-based approach analogous to echo-integration, this study estimated the relative biomass density and length distribution of fishes at seven toppled oil and gas platform jackets in a Reefed Jacket Zone (RJZ) in the nearshore western Gulf of Thailand in comparison with a nearby coral reef. Biomass density was comparable at each habitat, despite extreme variability across the RJZ, attributed to the spatiotemporal stochasticity of larger, schooling fishes. However, fishes were larger at the RJZ, a trend supported by simultaneous stereo-video footage. The relative benefits and drawbacks of imaging sonar encountered in this study are also described.

Unraveling trait‐based fish community assembly in tropical reservoirs

AbstractDamming of large rivers has promoted well‐documented ecosystem changes that constitute critical threats to freshwater fish biodiversity. However, it is unclear how trait–environment relationships drive community assembly in older (&gt;50 years) tropical river‐reservoir systems. We assessed physical features filtering functional traits (RLQ and fourth‐corner approaches) in seven tropical reservoirs along a major river, in southeastern Brazil, and correlated taxonomic and functional counterparts of local and beta diversity to assess niche‐based assembly processes under prevailing environmental conditions (null model approach). Lower littoral habitat availability (smaller area, volume, and riverine influence) favored species inhabiting open areas that feed on the bottom (mostly migratory species). Downstream position (lower elevation and inflow of water from the mainstem) allowed migrators to enter the reservoirs and promoted environmental heterogeneity, favoring detritivores, invertivores, and carnivorous generalists. Total blocking of the main channel excluded most migratory species from reservoirs at upstream reaches, whereas higher riverine influence and hydrological stability (larger area, volume, and water residence time) favored small‐sized sedentary species (omnivores and piscivores with parental care, mostly non‐native species) in the littoral zone. Correlations differing from null expectations for alpha diversity and nestedness revealed that niche‐based processes support species richness and loss under higher riverine influence and hydrological stability. Our study supports the importance of physical features to set functional spaces available for fish species, but random processes that boost taxonomic differences between reservoirs, largely related to non‐native species introductions, are the primary drivers of fish assemblage structure in tropical reservoirs long‐term disconnected from riverine dynamics.

Spatiotemporal dynamics of duck harvest distributions in the Central and Mississippi flyways, 1960–2019

AbstractGeographical distributions of waterfowl exhibit annual variation in response to spatiotemporal variation in weather conditions, habitat availability, and other factors. Continuing changes in climate and land use could lead to persistent shifts of waterfowl distributions, potentially causing a mismatch with habitat conservation planning, wetland restoration efforts, and harvest management decisions informed by historical distributions. We used band recoveries and harvest records (i.e., hunter‐harvested wings) from the United States Fish and Wildlife Service Waterfowl Parts Collection Survey as indices of duck distribution in autumn and winter, and quantified intra‐annual, interannual, and interspecific variation in their geographic distributions across 6 decades (1960–2019) for 15 duck species in the Central and Mississippi flyways in North America. Specifically, we tested for annual and decadal shifts in mean latitude and longitude of recoveries for each month (Oct–Jan) by species and taxonomic guild (i.e., dabbling, diving ducks). Overall, species varied in the extent, timing, and sometimes direction, of distributional change in recoveries. From 1960–2019, mean recovery locations for dabbling ducks shifted south 105–296 km in October and 27 km in November (wings only), whereas mean latitudes shifted north 144–234 km in December and 186–301 km in January. Mean recovery locations for diving ducks shifted north 162 km in October (wings only), 84–173 km in December, and 66–120 km in January, but shifted 99–512 km south in November. Shifts in longitude were less consistent between guilds and data types. Finally, distributional change rarely accelerated during recent decades, except for southward shifts of band recoveries of diving ducks in November and northward shifts of band and wing recoveries of dabbling ducks in January. Although anecdotal accounts of large‐scale northward shifts in duck distributions are prolific in the land management and hunting communities, our data demonstrate more subtle shifts that vary considerably by species and month. Observed changes in recovery distributions could necessitate changes in timing of habitat management practices throughout the Central and Mississippi flyways and may result in fewer hunting and recreational opportunities for some species in southern states. Quantifying patterns of historical change is a necessary first step to understanding temporal and interspecific variation in waterfowl distributions, which will help with landscape‐scale conservation and management efforts in the future and enable effective communication to core constituencies regarding ongoing changes and their implications for recreational engagement.

Hydro-morphological alteration and related effects on fish habitat induced by sediment management in a regulated Alpine river

Sediment pulses can cause relevant geomorphological alteration and fine sediment deposition, affecting the entire river ecosystem. Quantifying the impact of these events is becoming increasingly important, as sediment disturbance is predicted to intensify because of growing anthropogenic activity combined to the effects of current climate change. In this paper, the effects of a sediment pulse event on riverbed morphology and, in turn, on fish habitat availability are assessed in a regulated river, located in the southern European Alps. Specifically, four target fish species were selected: marble (Salmo marmoratus) and brown trout (Salmo trutta), grayling (Thymallus thymallus), and bullhead (Cottus gobio). The investigated event was triggered by the effects of localized landslides combined with an uncontrolled sediment release from a hydropower reservoir. A pre-post event integrated approach was applied, involving topographic surveys, fine sediment deposition measurements, and eco-hydraulic modeling. Habitat availability analysis was done using two-dimensional steady-state channel-flow simulation and standard habitat suitability modeling, with univariate suitability curves as biological input. The investigation focused on two river reaches, quite close each other, but characterized by significantly different streamflow patterns, due to the layout of the local hydropower system. The results showed that noticeable riverbed fining occurred at both study reaches after the pulse, with the maximum thickness of the fine sediment deposits up to one meter, and higher amounts of deposition detected in areas wetted at baseflow. Moreover, for both reaches, recovery to the pre-event riverbed grain-size condition occurred in about a year, but with differences related to different streamflow patterns. Pre-post topographic comparison showed that areas of erosion prevailed over areas of deposition, and fine sediment deposition was not systematically associated to the riverbed elevation raise. Simulated habitat availability was affected by both topographic changes and fine sediment deposition, with the latter predominantly impacting juveniles and the most bottom dwelling species, i.e., the bullhead. The study confirms the need for improving the management of the hydro-sedimentary regime of regulated rivers to preserve the habitat of fish species, particularly of those characterized by conservation status already endangered.

Spatio-temporal shifts in British wild bees in response to changing climate.

Climate plays a major role in determining where species occur, and when they are active throughout the year. In the face of a changing climate, many species are shifting their ranges poleward. Many species are also shifting their emergence phenology. Wild bees in Great Britain are susceptible to changes in climatic conditions but little is known about historic or potential future spatio-temporal trends of many species. This study utilized a sliding window approach to assess the impacts of climate on bee emergence dates, estimating the best temperature window for predicting emergence dates for 88 species of wild bees. Using a 'middle-of-the-road' (RCP 4.5) and 'worst-case' (RCP 8.5) climate scenario for the period 2070-2079, predictions of future emergence dates were made. In general, the best predicting climate window occurred in the 0-3 months preceding emergence. Across the 40 species that showed a shift in emergence dates in response to a climate window, the mean advance was 13.4 days under RCP 4.5 and 24.9 days under RCP 8.5. Species distribution models (SDMs) were used to predict suitable climate envelopes under historic (1980-1989), current (2010-2019) and future (2070-2079 under RCP 4.5 and RCP 8.5 scenarios) climate conditions. These models predict that the climate envelope for 92% of studied species has increased since the 1980s, and for 97% and 93% of species under RCP 4.5 and RCP 8.5 respectively, this is predicted to continue, due to extension of the northern range boundary. While any range changes will be moderated by habitat availability, it highlights that Great Britain will likely experience northward shifts of bee populations in the future. By combining spatial and temporal trends, this work provides an important step towards informing conservation measures suitable for future climates, directing how interventions can be provided in the right place at the right time.

Habitat selection of Gould’s wild turkeys in southeastern Arizona

In semi-arid environments, resources necessary for survival may be unevenly distributed across the landscape. Gould’s wild turkeys (Meleagris gallopavo mexicana) are spatially restricted to mountainous semi-arid areas of southwestern United States and Mexico, and information on their distribution and habitat use is limited. We described how landcover type and topographical features influenced space use and habitat selection by Gould’s wild turkeys in southeastern Arizona. We used GPS data from 51 Gould’s wild turkeys to describe resource selection during 2016–2017 in southeastern Arizona, USA. We estimated home ranges and calculated resource selection functions using distance from landcover types, slope, aspect, and elevation at used locations and random locations within individual home ranges. Gould’s wild turkeys selected areas closer to pine forest and water. Likewise, Gould’s wild turkeys selected locations with moderate elevations of 1641 ± 235 m (range = 1223–2971 m), and on north and west facing slopes with a 10° ± 8.5 (range = 0.0–67.4°) incline. Our findings suggest that conserving portions of the landscape with appropriate topography and landcover types as described above will promote habitat availability for Gould’s wild turkeys.

Deconstructing dams and disease: predictions for salmon disease risk following Klamath River dam removals

The health of fish populations and the river systems they inhabit have broad ecological, cultural, recreational, and economic relevance. This is exemplified by the iconic anadromous salmonid fishes native to the West Coast of North America. Salmon populations have been constrained since the mid nineteenth century by dam construction and water reallocation. In the Klamath River (Oregon and California, USA), a series of dams built in the early-mid 20th century cut the basin in two and blocked anadromous fish access to more than 600 river kilometers. This dramatic loss of habitat, coupled with infectious diseases and resulting epizootics, have impacted the wellbeing of these salmonid populations. In 2023-2024, the Klamath River will undergo the largest river restoration project in US history. Removal of the four lowermost dams will cause profound physical changes to the river, including flow, water temperature, and channel geomorphology. The dam removals will reconnect the lower and upper portions of the basin, and provide fish passage after a century of segregation. Reestablishment of upstream and downstream fish movements will also alter the occupancy and abundance of the salmonid hosts and their pathogens. The increased habitat availability and longer migration routes will increase duration of pathogen exposure and potential impacts on juvenile survival and adult pre-spawn mortality. However, restoration of more natural flow and sediment regimes will decrease overall fish disease risk by disrupting complex parasite life cycles. To better understand these multifarious, competing factors, we review the salmonid species in the Klamath River, and provide an overview of their historical pathogen challenges and associated diseases and use this as a framework to predict the effects of dam removals on disease dynamics. Our review and predictions are a synthesis of expertise from tribal biologists, fish health specialists and fish biologists, many of whom have lived and worked on the Klamath River for decades. We conclude with recommendations for expansion of current pathogen monitoring and research efforts to measure changes in host-pathogen dynamics basin-wide.

Movement behavior, habitat selection, and functional responses to habitat availability among four species of wintering waterfowl in California

IntroductionHabitat selection analyses provide a window into the perceived value of habitats by animals and how those perceptions compare with other animals, change across time, or change in relation to availability (termed functional responses). Habitat selection analysis and functional responses can be used to develop strategies to avoid habitat limitations, guide habitat management, and set attainable conservation goals. GPS relocations of marked animals are the principal data used in habitat selection analysis. The accuracy and frequency with which tracking devices collect data are increasing and may result in non-stationary point processes that result from latent behaviors previously unidentifiable in sparse data.MethodsWe investigated non-stationary step length distributions and integrated a two-mixture model of animal movement with step selection analysis to identify patterns of activity among four species of co-occurring waterfowl that winter in the Central Valley of California, United States. We evaluated relative strength of selection and compared functional responses across a range of habitat types for two goose and two dabbling duck species.ResultsGoose species (greater white-fronted goose [Anser albifrons] and lesser snow goose [Anser caerulescens caerulescens]) used habitats similarly and displayed similar functional responses with habitat availability. Northern pintail (Anas acuta) displayed functional responses for habitats that provided primary food resources and sanctuary from hunting that were more similar to geese than to mallard (Anas platyrhynchos), which expressed a more generalist pattern of habitat selection.DiscussionOur results define conditions where food resource competition between geese and ducks could operate, which indicate that some species may be more impacted than others. Specifically, early season food limitation may manifest more strongly in snow geese due to longer movements and stronger functional response with rice availability. Late season limitations may manifest in northern pintail, which remain reliant on rice later but may not be reflected in habitat selection patterns due to a consistent functional response with rice availability. We show that multiple movement processes present in high-resolution data can be used to obtain a variety of information about animal behavior and that subsequent step selection analyses may demonstrate unique functional responses relative to alternate habitat selection methods that warrant additional investigation.