Modeling non-stationary urban growth: The SPRAWL model and the ecological impacts of development

Urban development is a principal driver of landscape change affecting the integrity of ecological systems and the capacity of the landscape to support species. We developed an urban growth model (SPRAWL), evaluated it with hindcasting, and used it to simulate urban growth across the northeastern United States between 2010 and 2080 under four alternative scenarios. In the model, urban growth is constrained by demand for new development for each time step at the subregional scale. Demand is subsequently allocated to local application panes (5 km on a side within 15 km window) using a unique landscape context matching algorithm, such that the more historical development that occurred in the matched training windows the higher the proportion of future demand assigned to the pane. Lastly, demand in each pane is allocated among development types and then allocated to individual patches based on suitability surfaces unique to that landscape context. SPRAWL has a multi-level, multi-scale structure that captures urban growth drivers operating at multiple scales and, when combined with the unique matching and suitability algorithms, induces non-stationarity in urban growth across time and space. Our evaluation indicated that SPRAWL was highly discriminatory, well-calibrated, and highly predictive of new development, but performed weakly for redevelopment transitions. We evaluated the ecological impacts of four alternative urban growth scenarios varying in total demand for new development and “sprawliness” of new development relative to historical patterns using an ecological integrity index. The results were consistent with expectations and demonstrated the potential of SPRAWL for scenario analysis

Large-scale collaboration reveals landscape-level effects of land-use on turtle demography

Freshwater turtles and tortoises are declining worldwide and currently represent one of the most imperiled major vertebrate groups. Identifying the conditions that promote long-term viable populations is a critical conservation need. However, for most species, there is relatively little or no empirical information about the factors influencing population demographics. Large-scale population monitoring efforts necessary to acquire such information remain rare due to the logistic challenges associated with low and variable detectability, which generally preclude large monitoring initiatives by any single entity. The development of collaborative population monitoring programs represents one potential strategy for overcoming these challenges. Our goal was to leverage partnerships to identify the potential factors and relevant scales affecting wood turtle (Glyptemys insculpta) population demographics. Through a large-scale collaborative multi-institutional monitoring effort, we conducted 983 spring stream surveys at 293 sites across the northeastern United States. Wood turtle abundance was negatively associated with agriculture (300 m and 5500 m) and road traffic (5500 m) and positively associated with mature forest (5500 m). Juvenile proportion displayed strong negative relationships with stream gradient and imperviousness (300 m). Sex ratios were more male-skewed with higher mature forest cover (90 m) and road density (5500 m) and less undeveloped land (300 m). These findings suggest that effective conservation of demographically robust turtle populations will require consideration of multiple spatial scales. Landscape-level conservation may be particularly important for ensuring long-term viable populations. This study highlights the valuable role that collaboration across institutions and jurisdictions can play in the conservation of cryptic taxa

Spatial ecology of eastern box turtles (Terrapene c. carolina) in central Massachusetts

Eastern box turtles are declining throughout their range as a result of habitat loss and fragmentation, associated road mortality, collection for the pet trade, and other localized threats such as incidental collection, disease, mowing, and fire. We evaluated the geomorphic habitat suitability for Eastern box turtles in Massachusetts using a Mahalanobis distance modeling approach. To evaluate habitat use, home range size, and box turtle population status in the Connecticut River Valley, Massachusetts, we conducted a four year mark-recapture and radio-telemetry effort. We surveyed over 30 sites, captured 191 animals and radio-tracked 91 animals at eight sites for 1-4 years for a total of 217 turtle-years. Estimated population sizes at these sites ranged from a summer high of 3.8 to a winter low of 0.3 turtles/ha. Home range size ranged from 140–2145 m straight line and 0.5–136 ha. These densities are much lower and home range sizes much larger than reported throughout the rest of the species range. Conservation efforts based on data from previous studies elsewhere in the species range would have underestimated habitat requirements and space needs, highlighting the need for local and regional information when planning for rare species conservation. We evaluated over-wintering habitat at multiple levels of habitat selection and spatial scales using logistic regression and classification trees in conjunction with remotely sensed geomorphic and land-use variables. We also conducted a micro-habitat assessment of over-wintering sites using variables measured in the field. Microtopography proved important, with 59% of transmitting turtles over-wintering in depressions (typically behind tip-up mounds of fallen trees). Other variables distinguishable between turtle and random locations were high basal areas of hardwood trees and abundant downed wood and mountain laurel. These results can be used to inform management practices and focus future survey efforts. We evaluated the influence of landscape composition and structure on the movements of box turtles using mixed effects linear regression models. Eastern box turtles have smaller home ranges in more urbanized landscapes and move further in more forested, less fragmented areas. The relationship varies significantly by site, underscoring the importance of evaluating effects across multiple sites, and suggesting that single-site studies may not be generalizable throughout regions. Population density estimates from five of the sites suggest a unimodal rather than linear relationship with urbanization. The highest-density site had a moderate level of fragmentation, suggesting that low levels of urbanization may be compatible with Eastern box turtle conservation, but that high levels of fragmentation may be detrimental to box turtle populations. Early successional habitat comprised more than 50% of June locations, suggesting these habitat features are important and may be limited on the landscape. We evaluated whether habitat management to create such areas could be effective by using utility distribution volume and a randomization approach to assess habitat use before and after forest was cleared at two sites. Use of the treatment areas increased significantly after clearing. Our results suggest that Eastern box turtles are willing to incorporate newly cleared areas into their home range within one year, and that it may be possible to improve habitat and minimize movement distance through active management. We also characterized seasonal movement and activity patterns, nesting habitat and reproductive parameters, and adult mortality rates. We suspect that mortality rates are much higher statewide and that habitat loss is likely the largest cause of mortality. Using our observed clutch size, nest success rate, and adult mortality rate and a deterministic population model, we estimated that hatchling and juvenile survival rates must exceed 77.6% annually in order to maintain a stable population in the absence of stochastic events. This survival rate is unrealistically high, particularly since the model does not account for variability and we suspect that our adult survival rate was artificially inflated, suggesting that populations may be declining in the Connecticut River Valley, even at protected sites. (Abstract shortened by UMI.

Estimating poaching risk for the critically endangered wild red wolf (Canis rufus).

The reintroduced red wolf (Canis rufus) population in northeastern North Carolina declined to 7 known wolves by October 2020, the majority of which is due to poaching (illegal killing), the major component of verified anthropogenic mortality in this and many other carnivore populations. Poaching is still not well understood and is often underestimated, partly as a result of cryptic poaching, when poachers conceal evidence. Cryptic poaching inhibits our understanding of the causes and consequences of anthropogenic mortality, which is important to conservation as it can inform us about future population patterns within changing political and human landscapes. We estimate risk for marked adult red wolves of 5 causes of death (COD: legal, nonhuman, unknown, vehicle and poached) and disappearance, describe variation in COD in relation to hunting season, and compare time to disappearance or death. We include unknown fates in our risk estimates. We found that anthropogenic COD accounted for 0.78-0.85 of 508 marked animals, including poaching and cryptic poaching, which we estimated at 0.51-0.64. Risk of poaching and disappearance was significantly higher during hunting season. Mean time from collaring until nonhuman COD averaged 376 days longer than time until poached and 642 days longer than time until disappearance. Our estimates of risk differed from prior published estimates, as expected by accounting for unknown fates explicitly. We quantify the effects on risk for three scenarios for unknown fates, which span conservative to most likely COD. Implementing proven practices that prevent poaching or hasten successful reintroduction may reverse the decline to extinction in the wild of this critically endangered population. Our findings add to a growing literature on endangered species protections and enhancing the science used to measure poaching worldwide

Passive transport of Eastern Elliptio (Elliptio complanata) by freshwater turtles in New England

Dispersal of freshwater mussels (order Unionida) is primarily as glochidia on the fins and gills of host fish. Adult mussels are more sessile, generally moving short distances (<2 m/week) along lake and river beds. Between 2007 and 2016, we observed seven instances of adult Eastern Elliptio (Elliptio complanata) and one instance of a fingernail clam (Sphaerium sp.) attached to the feet of freshwater turtles in streams and ponds of New England, United States. Observations included five instances of mussels attached to Wood Turtles (Glyptemys insculpta) in Maine and Massachusetts, one instance of a mussel attached to the fingernail of an Eastern Painted Turtle (Chrysemys picta) in Massachusetts, one instance of a mussel attached to a Snapping Turtle (Chelydra serpentina) in Massachusetts, and one instance of a fingernail clam attached to the fingernail of an Eastern Painted Turtle in Massachusetts. We suggest that Eastern Elliptio may be susceptible to transport by freshwater turtles foraging in mussel beds and that transport of adult mussels by freshwater turtles could result in otherwise atypical long-distance, upstream, or overland dispersal between waterbodies