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Current (as of 2014) distribution of sandhill crane Grus canadensis populations throughout North America (USFWS 2009).
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Population delineation throughout the annual life cycle for migratory birds is needed to formulate regional and national management and conservation strategies. Despite being well studied continentally, connectivity of sandhill crane Grus canadensis populations throughout the western portion of their North American range remains poorly described. O...
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... Cranes in the subfamily Gruinae are composed of species known to be impacted by various weather conditions during migration, especially due to their relatively large size and reliance on a mix of flapping-powered and soaring flight (Pennycuick et al., 1979;Alonso et al., 1990a;Ojaste et al., 2020). There are six distinct migratory populations of sandhill cranes in North America, and they are composed of up to two subspecies (Collins et al., 2016;Petersen et al., 2003;Johnson et al., 2005). The greater sandhill crane (Antigone canadensis tabida) is the largest subspecies of sandhill cranes and makes up the Rocky Mountain Population (RMP). ...
The Rocky Mountain Population (RMP) of greater sandhill cranes uses a key stopover area, the San Luis Valley (SLV) in Colorado. Parameters of migration phenology can differ between autumn and spring and are affected by weather and environmental factors. We hypothesized that sandhill cranes in the SLV would have a longer stopover duration in autumn than in spring, and that wind assistance, crosswinds, temperature change, barometric air pressure, and surface water area would influence persistence probability. We used data from sandhill cranes fitted with transmitters that spanned autumn and spring, 2015-2022. We used an open robust design mark-recapture model to estimate stopover duration, arrival probability, and persistence probability. We examined the effects of weather and surface water on the persistence probability for 106 sandhill cranes in the SLV. Stopover duration was longer in autumn than in spring and had higher variability across years. Arrival probability to the SLV peaked on 13 October in autumn and 21 February in spring. Persistence probability declined around mid-December in autumn and mid-March in spring. We found that several weather covariates influenced persistence in both seasons. In autumn, sandhill cranes departed the SLV with higher tailwinds, lower crosswinds, and higher surface water availability. In spring, sandhill cranes departed the SLV with lower crosswinds and higher barometric air pressure at the surface and higher wind speeds at altitudes of about 3,000 m. The effect of wind speed was stronger later in the spring. Given the lower variability of arrival and persistence probability and shorter stopover duration in spring compared to autumn, we suspect that RMP sandhill cranes are using a time-minimization strategy during spring. However, given the use of supportive winds and weather conditions ideal for soaring, RMP sandhill cranes appear to be using strategies that save energy in both seasons. Our study identifies the optimal timing of water management and surveys for RMP sandhill cranes and confirms that weather influences their persistence. Understanding differences in migration patterns between seasons and the factors that influence persistence at stopover sites will also be important for anticipating phenological impacts from climate change and land use alterations.
... Beginning in 2015, data from cranes fitted with global positioning systems (GPS) satellite platform transmitter terminals (PTT) have provided valuable migration timing and location information. These cranes are being marked as part of a larger study of RMP cranes (Boggie et al. 2018, Collins et al. 2015. The SLV is the major migration stop for RMP cranes that breed primarily in Idaho, Montana, Utah, and Wyoming (Drewien et al. 1995). ...
... Approximately 685,000 summering bird locations were collected from 2014 to 2022 (Figure 1), with over 85% of days containing seven or more acquisitions per 24 h. Detailed capture and GPS deployment procedures are provided by Collins and Grisham (2016) and Boggie and Collins (2018). interacted with landscapes (Fauchald & Tveraa, 2003). ...
Information about species distributions is lacking in many regions of the world, forcing resource managers to answer complex ecological questions with incomplete data. Information gaps are compounded by climate change, driving ecological bottlenecks that can act as new demographic constraints on fauna. Here, we construct greater sandhill crane ( Antigone canadensis tabida ) summering range in western North America using movement data from 120 GPS‐tagged individuals to determine how landscape composition shaped their distributions. Landscape variables developed from remotely sensed data were combined with bird locations to model distribution probabilities. Additionally, land‐use and ownership were summarized within summer range as a measure of general bird use. Wetland variables identified as important predictors of bird distributions were evaluated in a post hoc analysis to measure long‐term (1984–2022) effects of climate‐driven surface water drying. Wetlands and associated agricultural practices accounted for 1.2% of summer range but were key predictors of occurrence. Bird distributions were structured by riparian floodplains that concentrated wetlands, and flood‐irrigated agriculture in otherwise arid and semi‐arid landscapes. Findings highlighted the role of private lands in greater sandhill crane ecology as they accounted for 78% of predicted distributions. Wetland drying observed in portions of the range from 1984 to 2022 represented an emerging ecological bottleneck that could limit future greater sandhill crane summer range. Study outcomes provide novel insight into the significance of ecosystem services provided by flood‐irrigated agriculture that supported nearly 60% of wetland resources used by birds. Findings suggest greater sandhill cranes function as a surrogate species for agroecology and climate change adaptation strategies seeking to reduce agricultural water use through improved efficiency while also maintaining distinct flood‐irrigation practices supporting greater sandhill cranes and other wetland‐dependent wildlife. We make our wetland and sandhill crane summering distributions available as interactive web‐based mapping tools to inform conservation design.
... Approximately 685,000 summering bird locations were collected from 2014 to 2022(Figure 1), with over 85% of days containing seven or more acquisitions per 24 hours. Detailed capture and GPS deployment procedures are provided byCollins et al. (2016) andBoggie et al. (2018). ...
Information about species distributions is lacking in many regions of the world, forcing resource managers to answer complex ecological questions with incomplete data. Information gaps are compounded by climate change, driving ecological bottlenecks that can act as new demographic constraints on fauna. Here, we construct greater sandhill crane (Antigone canadensis tabida) summering range in western North America using movement data from 120 GPS-tagged individuals to determine how landscape composition shaped their distributions. Landscape variables developed from remotely sensed data were combined with bird locations to model distribution probabilities. Additionally, land-use and ownership were summarized within summer range as a measure of general bird use. Wetland variables identified as important predictors of bird distributions were evaluated in a post hoc analysis to measure long-term (1984–2022) effects of climate-driven surface water drying. Wetlands and associated agricultural practices accounted for 1.2% of summer range but were key predictors of occurrence. Bird distributions were structured by riparian floodplains that concentrated wetlands, and flood-irrigated agriculture in otherwise arid and semi-arid landscapes. Findings highlighted the role of private lands in greater sandhill crane ecology as they accounted for 78% of predicted distributions. Wetland drying observed in portions of the range from 1984 to 2022 represented an emerging ecological bottleneck that could limit future greater sandhill crane summer range. Study outcomes provide novel insight into the significance of ecosystem services provided by flood-irrigated agriculture that supported nearly 60% of wetland resources used by birds. Findings suggest greater sandhill cranes function as a surrogate species for agroecology and climate change adaptation strategies seeking to reduce agricultural water use through improved efficiency while also maintaining distinct flood-irrigation practices supporting greater sandhill cranes and other wetland-dependent wildlife. To inform conservation design, we make our wetland and sandhill crane summering distributions available as interactive web-based mapping tools.
... We captured cranes using rocket nets at Cibola NWR, Sonny Bono Salton Sea NWR and a private landholding outside of Brawley, CA during January and February 2014 and a summering area (Long Valley, Idaho) August 2014 (Wheeler and Lewis 1972, Urbanek et al. 1991, Collins et al. 2015, Conring 2016. Upon capture, we banded each crane with a size 9 lock-on U.S. Geological Survey aluminum band. ...
... The band was placed above the right tibiotarsus of each crane. From each capture, we selected a subset (see for details : Collins et al. 2015, Conring et al. 2019) of adult cranes and affixed a platform transmitter terminal (PTT; white alphanumeric code, X00-X19, on black background) on their left tibiotarsus with the antennae pointed towards the feet and solar panels forward. We used head plumage characteristics (Lewis 1979) to identify and age adult cranes and collected the following information for each capture: location, method, bird identification (ID) number, band number, age (After Hatch Year, Hatch Year, or Second Year), and transmitter ID for selected adults. ...
Wetlands in arid and semiarid regions are recognized as priority ecosystems for conservation of wetland-dependent species in these systems. Evaluation of habitat selection is necessary for effective habitat management and, consequently, population management. The Lower Colorado River Valley population of Greater Sandhill Cranes (Antigone canadensis tabida), winters exclusively in portions of southwestern Arizona and southeastern California. Therefore, there is a need for information pertaining to winter habitat selection to guide management decisions. We attached solar-powered satellite platform transmitter terminals to greater Sandhill Cranes and used daily global positioning system locations. Each used location paired with 10 randomly generated locations had equal probability of drawing any of the randomly generated locations. We evaluated habitat selection and found the model that included land use type (β = –5.85, SE = 0.23, P < 0.001) and distance to roost (β = –4.61, SE = 0.16, P < 0.001) as interactive effects was the most supported model in the candidate set. Our results emphasize the importance of maintaining wetlands in close proximity (∼ 5 km) to selected land use types, which can be challenging to manage for in arid systems but are particularly necessary for this high conservation priority population of greater Sandhill Cranes.
... = 0.21). Research indicates that this population may be somewhat integrated with the RMP (Collins et al. 2016). ...
Population estimates provide important information for wildlife species management and drive decision-making regarding strategic habitat protection, conservation status (e.g., State Wildlife Action Plans), and hunting regulations. Sandhill Cranes (Grus [Antigone] canadensis) apparently represent the most abundant Gruidae species globally, but few documents integrate abundance estimates and trends for distinct population segments and subspecies. This investigation estimates the minimum population sizes for all six migratory populations and three non-migratory subspecies using 5-year maximum values from existing survey data following Caven et al. (2020). The percent annual growth rate of populations are also estimated using log-transformed bivariate ordinary least squares regression models in the absence of published population trends. The results of this investigation suggest that there are at least 1.45 million Sandhill Cranes in the world, which roughly equals the population of all other 14 extant crane species combined. Despite these impressive numbers, Sandhill Crane populations pale in comparison to those of several other large-bodied waterbirds (e.g., Snow Geese number ~16 million). The Mid-continent Population represents the largest segment and comprises nearly 88% of all Sandhill Cranes globally, while the two smallest populations, the Cuban (G. c. nesiotes) and Mississippi (G. c. pulla) subspecies, respectively account for less than 0.1% combined. Annual population growth rates were apparently low for non-migratory subspecies (mean ≈0%) but relatively high for migratory populations (mean ≈3%). This literature and data review highlights uncertainties regarding the status of the Cuban Sandhill Crane, the Florida Sandhill Crane (G. c. pratensis), and the Central Valley Population (CVP) of Greater Sandhill Cranes (G. c. tabida), which winters in California. Based on small populations and low growth rates, conservation efforts should likely focus on non-migratory populations and the CVP. However, habitat protection and restoration at important wintering and stopover areas for larger populations (e.g., Muleshoe National Wildlife Refuge, TX; Platte River, NE) also remains important as high Sandhill Crane concentrations could result in significant disease outbreaks and subsequent mortality, especially considering the emergence of highly pathogenic avian influenza (H5N1/8).
... We captured cranes using rocket nets at Cibola NWR, Sonny Bono Salton Sea NWR and a private landholding outside of Brawley, CA during January and February 2014 and a summering area (Long Valley, Idaho) August 2014 (Wheeler and Lewis 1972, Urbanek et al. 1991, Collins et al. 2015, Conring 2016. Upon capture, we banded each crane with a size 9 lock-on U.S. Geological Survey aluminum band. ...
... The band was placed above the right tibiotarsus of each crane. From each capture, we selected a subset (see for details : Collins et al. 2015, Conring et al. 2019) of adult cranes and affixed a platform transmitter terminal (PTT; white alphanumeric code, X00-X19, on black background) on their left tibiotarsus with the antennae pointed towards the feet and solar panels forward. We used head plumage characteristics (Lewis 1979) to identify and age adult cranes and collected the following information for each capture: location, method, bird identification (ID) number, band number, age (After Hatch Year, Hatch Year, or Second Year), and transmitter ID for selected adults. ...
Wetlands in arid and semiarid regions are recognized as priority ecosystems for conservation of wetland-dependent species in these systems. Evaluation of habitat selection is necessary for effective habitat management and, consequently, population management. The Lower Colorado River Valley population of greater sandhill cranes (Antigone canadensis tabida), winters exclusively in portions of southwestern Arizona and southeastern California. Therefore, there is a need for information pertaining to winter habitat selection to guide management decisions. We attached solar-powered satellite platform transmitter terminals to greater sandhill cranes and used daily global positioning system locations. Each used location paired with 10 randomly generated locations had equal probability of drawing any of the randomly generated locations. We evaluated habitat selection and found the model that included land use type (β = -5.8481, SE = 0.2281, p < 0.001) and distance to roost (β = -4.6079, SE = 0.1643, p < 0.001) as interactive effects was the most supported model in the candidate set. Our results emphasize the importance of maintaining wetlands in close proximity (~ 5km) to selected land use types, which can be challenging to manage for in arid systems but are particularly necessary for this high conservation priority population of greater sandhill cranes.
... Deployment in summering areas was focused strategically in regions that closed monitoring gaps in underrepresented portions of the summering range (Donnelly et al., 2021). Detailed capture and GPS deployment procedures are provided in Collins et al. (2015) and . ...
Managers typically estimate wildlife abundance using surveys within a timeframe that favors increased detectability; however, the ability to account for probabilities of inclusion, detection, and/or presence within a given sampling area is often limited. Cranes provide a good opportunity to research count accuracy because they are large, conspicuous, and often congregate during part of the year, typically on staging areas (i.e., fall and spring) or on wintering grounds. The objectives of this paper are twofold: (1) to evaluate how environmental factors influence crane movement in and out of crane survey areas to identify the best window of availability for annual survey counts; and (2) to evaluate environmental factors that influence overall crane survey counts from year to year. For Objective 1, a generalized linear mixed model was selected to model the probability of crane presence within survey areas using GPS transmitter data. A binary response variable representing crane movement within and outside formal survey areas was used as the dependent variable to investigate environmental covariates that influence movement into survey areas. Probability of crane presence was explained by seven covariates plus a quadratic term for Julian day number. Interactions between Palmer drought severity index (PDSI) and normalized difference vegetation index supported higher probability of crane presence in survey areas during times of drought. Probability of crane presence increased throughout the entire study period (May–October), suggesting that formal surveys in September could be augmented or replaced by surveys in October. For Objective 2, a negative binomial model with linear parameterization was selected to model crane counts using census data compiled from 1995 to 2019. Covariates were acquired at the watershed scale using Hydrologic Unit Code 6 boundaries. Of the 17 covariates investigated, we found that 18‐month precipitation (PPTgss), PDSI, and minimum temperature (Tempmin) explained most of the variability in crane census counts. High PPTgss (antecedent moisture), low PDSI (drought conditions), and low Tempmin (cold extremes) result in higher annual crane counts. The ability to link ecological processes to wildlife movement and population abundance both locally and at landscape scales has long‐ranging implications on resource projections, conservation, and the ability to deploy adaptive management.
... From 2014-2020 we used rocket nets to capture wintering cranes at the BdANWR and areas within the Ladd S. Gordon Waterfowl Complex, along with a small number of cranes in the RMP on the breeding grounds (Collins et al. 2015, Boggie et al. 2018b. For captured greater sandhill cranes, we applied size 9 United States Geological Survey (USGS) individually numbered aluminum bands on the left tibia. ...
... For captured greater sandhill cranes, we applied size 9 United States Geological Survey (USGS) individually numbered aluminum bands on the left tibia. Additionally, we fitted a subset of captured adult greater sandhill cranes (n = 81) with satellite-based telemetry tags, using a modified leg band with auxiliary markers to attach the devices to the right tibia (Collins et al. 2015, Boggie et al. 2018b. We placed the telemetry device and USGS aluminum band above the tibio-tarsus. ...
Infrastructure development can affect avian populations through direct collision mortality. Estimating the exposure of local bird populations to the risk of direct mortality from infrastructure development requires site-and species-specific data, which managers may find difficult to obtain at the scale over which management decisions are made. We quantify the potential exposure of sandhill cranes (Antigone canadensis) to collision with horizontal structures (e.g., transmission lines) within vital wintering grounds of the Middle Rio Grande Valley (MRGV), New Mexico, USA, 2014-2020. Limited maneuverability and visual acuity make sandhill cranes vulnerable to collisions with infrastructure bisecting their flight paths. We used data from 81 global positioning system (GPS)-tagged cranes to estimate the spatially explicit flight height distribution along the MRGV, the passage rate across hypothetical transmission lines, and the resulting exposure rate (exposed passes/crane/day). The exposure rate ranged from 0-0.28 exposed passes/crane/day (median = 0.015) assuming an exposure zone of 7-60 m above ground level, and identified hotspots of potential exposure within the MRGV. Mapped exposure rates can assist in the siting of proposed high-voltage transmission lines, or other infrastructure, to limit effects on sandhill cranes and other avian species at risk of collision. Our approach can be replicated and applied in similar situations where birds are exposed to possible collision with power lines.
... In total, 187 unique northward spring migrations and 150 southward fall migrations were spatially inventoried. Detailed capture and GPS deployment procedures are provided in Collins et al. (2016b), Nowak et al. (2018), and Boggie et al. (2018). ...
Collins. 2021. Migration efficiency sustains connectivity across agroecological networks supporting sandhill crane migration. Ecosphere 12(6): Abstract. Preserving avian flyway connectivity has long been challenged by our capacity to meaningfully quantify continental habitat dynamics and bird movements at temporal and spatial scales underlying long-distance migrations. Waterbirds migrating hundreds or thousands of kilometers depend on networks of wetland stopover sites to rest and refuel. Entire populations may rely on discrete wetland habitats, particularly in arid landscapes where the loss of limited stopover options can have disproportionately high impacts on migratory cost. Here, we examine flyway connectivity in water-limited ecosystems of western North America using 108 GPS tagged greater sandhill cranes. Bird movements were used to reconstruct wetland stopover networks across three geographically unique sub-populations spanning 12 U.S.-Mexican states and Canadian provinces. Networks were monitored with remote sensing to identify long-term (1988-2019) trends in wetland and agricultural resources supporting migration and evaluated using network theory and centrality metrics as a measure of stopover site importance to flyway connectivity. Sand-hill crane space use was analyzed in stopover locations to identify important ownership and landscape factors structuring bird distributions. Migratory efficiency was the primary mechanism underpinning network function. A small number of key stopover sites important to minimizing movement cost between summering and wintering locations were essential to preserving flyway connectivity. Localized efficiencies were apparent in stopover landscapes given prioritization of space use by birds where the proximity of agricultural food resources and flooded wetlands minimized daily movements. Model depictions showing wetland declines from 16% to 18% likely reflect a new normal in landscape drying that could decouple agriculture-waterbird relationships as water scarcity intensifies. Sustaining network resilience will require conservation strategies to balance water allocations preserving agricultural and wetlands on private lands that accounted for 67-96% of habitat use. Study outcomes provide new perspectives of agroecological relationships supporting continental waterbird migration needed to prioritize conservation of landscapes vital to maintaining flyway connectivity.
