A common thought among graduate students is: “how do established scientists get where they are today?” In Serendipity: An Ecologist’s Quest to Understand Nature, James Estes offers a personal reflection on research experiences spanning his 50-year career, beginning as a Ph.D. student in 1970 and concluding with recognition as a member of the National Academy of Sciences in 2014. Estes chronologically outlines the foundational trophic cascade ecology research that he and colleagues conducted in the Aleutian Islands, examining key relationships among kelp forests, sea otters, sea urchins, and killer whales through anecdotal stories of achievement and challenge. Estes’ 3 main goals in writing this book are to: (1) recount what he had learned from 50 years of research; (2) provide a larger story of how predators and prey interact with one another; and (3) explain how science “really happens.”

The last comprehensive nest survival study of the breeding giant Canada goose (Branta canadensis maxima) population in Iowa, USA, was conducted >30 years ago during a period of population recovery, during which available nesting habitat consisted primarily of artificial nest structures. Currently, Iowa's resident goose population is stable and nests in a variety of habitats. We analyzed the effects of available habitat on nest survival and how nest survival rates compared with those of the expanding goose population studied previously to better understand how to maintain a sustainable Canada goose population in Iowa. We documented Canada goose nest survival at rural wetland sites in north-central Iowa. We monitored 121 nests in 2013 and 149 nests in 2014 at 5 Wildlife Management Areas (WMAs) with various nesting habitats, including islands, muskrat (Ondatra zibethicus) houses, and elevated nest structures. We estimated daily nest-survival rate using the nest survival model in Program MARK. Survival was influenced by year, site, stage, presence of a camera, nest age, and an interaction between nest age and stage. Nest success rates for the 28-day incubation period by site and year combination ranged from 0.10 to 0.84. Nest survival was greatest at sites with nest structures (β = 17.34). Nest survival was negatively affected by lowered water levels at Rice Lake WMA (2013 β = −0.77, nest age β = −0.07). Timing of water-level drawdowns for shallow lake restorations may influence nest survival rates. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

In 2003, a reintroduction program was initiated at Badlands National Park (BNP), South Dakota, USA, with swift foxes (Vulpes velox) translocated from Colorado and Wyoming, USA, as part of a restoration effort to recover declining swift fox populations throughout its historical range. Estimates of age-specific survival are necessary to evaluate the potential for population growth of reintroduced populations. We used 7 years (2003–2009) of capture–recapture data of 243 pups, 29 yearlings, and 69 adult swift foxes at BNP and the surrounding area to construct Cormack–Jolly–Seber model estimates of apparent survival within a capture–mark–recapture framework using Program MARK. The best model for estimating recapture probabilities included no differences among age classes, greater recapture probabilities during early years of the monitoring effort than later years, and variation among spring, winter, and summer. Our top ranked survival model indicated pup survival differed from that of yearlings and adults and varied by month and year. The apparent annual survival probability of pups (0.47, SE = 0.10) in our study area was greater than the apparent annual survival probability of yearlings and adults (0.27, SE = 0.08). Our results indicate low survival probabilities for a reintroduced population of swift foxes in the BNP and surrounding areas. Management of reintroduced populations and future reintroductions of swift foxes should consider the effects of relative low annual survival on population demography.

Increased understanding of the influence of habitat (e.g., composition, patch size) and intrinsic (e.g., age, birth mass) factors on survival of neonatal pronghorn (Antilocapra americana) is a prerequisite to successful management programs, particularly as they relate to population dynamics and the role of population models in adaptive species management. Nevertheless, few studies have presented empirical data quantifying the influence of habitat variables on survival of neonatal pronghorn. During 2002–2005, we captured and radiocollared 116 neonates across two sites in western South Dakota. We documented 31 deaths during our study, of which coyote (Canis latrans) predation (n = 15) was the leading cause of mortality. We used known fate analysis in Program MARK to investigate the influence of intrinsic and habitat variables on neonatal survival. We generated a priori models that we grouped into habitat and intrinsic effects. The highest-ranking model indicated that neonate mortality was best explained by site, percent grassland, and open water habitat; 90-day survival (0.80; 90% CI = 0.71–0.88) declined 23% when grassland and water increased from 80.1 to 92.3% and 0.36 to 0.40%, respectively, across 50% natal home ranges. Further, our results indicated that grassland patch size and shrub density were important predictors of neonate survival; neonate survival declined 17% when shrub density declined from 5.0 to 2.5 patches per 100 ha. Excluding the site covariates, intrinsic factors (i.e., sex, age, birth mass, year, parturition date) were not important predictors of survival of neonatal pronghorns. Further, neonatal survival may depend on available land cover and interspersion of habitats. We have demonstrated that maintaining minimum and maximum thresholds for habitat factors (e.g., percentages of grassland and open water patches, density of shrub patches) throughout natal home ranges will in turn, ensure relatively high (>0.50) neonatal survival rates, especially as they relate to coyote predation. Thus, landscape level variables (particularly percentages of open water, grassland habitats, and shrub density) should be incorporated into the development or implementation of pronghorn management plans across sagebrush steppe communities of the western Dakotas, and potentially elsewhere within the geographic range of pronghorn.

Since the early 1990s, >5,000 ha of historic wetlands (and adjacent prairie) have been restored on the row-crop agricultural landscape of Winnebago County, Iowa, USA. From 2008–2011, we surveyed 22 of these sites for probabilities of occupancy and colonization by Boreal Chorus Frogs (BCF; Pseudacris maculata), Northern Leopard Frogs (NLF; Lithobates pipiens), and American Toads (AT; Anaxyrus americanus). We used radio telemetry to measure patterns of movement and habitat use by 22 NLF and 54 AT and deployed biophysical models in available habitats to estimate their physiological costs. The BCF occupied 100% of restored wetlands; NLF and AT occupied 59–91% and 71–89%, respectively, varying according to annual weather conditions. The BCF colonized new sites within a year; NLF and AT required 3 and 2 yr, respectively. These differences were related to distances from the nearest established population and costs of intervening cover types, and were statistically related to the size and orientation of restored wetlands. The ranges of maximum straight-line distances moved by NLF and AT were 31–857 m and 42–2,932 m, respectively. Both NLF and AT selected wetlands and surrounding prairies, though NLF were nine times more likely to select wetland habitats than all others combined. About 24% of AT used row-crop fields extensively, but not until crops had grown sufficiently to reduce the physiological costs of these fields similar to that of prairies. Both BCF and AT navigated the dramatically altered row-crop landscape, but NLF depended more heavily on roadside ditches to find and colonize restored wetlands.

Reproductive success of mallards (Anas platyrhynchos) is influenced by distribution and amount of wetlands and grasslands on the landscape during the breeding season. Most studies of mallard reproductive success have been conducted in areas with high wetland densities and large tracts of grasslands. We investigated nest survival of mallards in intensively cropped northern Iowa, USA, where wetland and grassland habitats were highly fragmented. We radiotracked female mallards nesting during 1998–2000 and located 318 nests in 6 types of land cover. Overall daily survival rate of nests was 0.945 ± 0.003 standard error (SE), corresponding to an estimated nest survival rate of 0.14. Hen success (i.e., the probability that an individual female will hatch a nest in one of her attempts) averaged 0.28 ± 0.03 SE. We used a model selection approach to examine covariates that might affect nest survival. Perimeter-to-area ratio (PAR) of the nest patch was the most important predictor of daily nest survival, with nest survival decreasing with increasing PAR. A greater percentage of nests hatched (18%) in habitats with low perimeter-to-area ratios (e.g., pastures, hayfields, Conservation Reserve Program fields, and managed grasslands) compared with habitats with high PAR (11%) such as drainage ditches, road-side ditches, fencerows, and waterways. Managing habitat in this region to increase mallard nest survival will be challenging, given the propensity of mallards to nest in linear habitats. If the climate change projections materialize in the 21st century, the southeastern portion of the Prairie Pothole Region could become a much more important breeding area for midcontinent mallards. Published 2016. This article is a U.S. Government work and is in the public domain in the USA.

In recent years, anthropogenic conversion of grassland habitat has raised concerns about the status of breeding Swainson's Hawks (Buteo swainsoni) in the northern Great Plains region of North America. During 2013–2014, we captured breeding Swainson's Hawks in north-central South Dakota and south-central North Dakota to estimate home-range size, determine adult survival rates during the breeding season, and evaluate habitat selection. We captured, radio-tagged, and monitored 13 Swainson's Hawks in 2013, and captured two additional Swainson's Hawks in 2014. In 2014, seven of 13 individuals initially captured in 2013 returned to the same breeding territory for the 2014 breeding season. Average 95% MCP home-range size in 2013 was 205.4 ha (SD = 135.3 ha, n = 10) and 211.1 ha (SD = 208.8 ha, n = 9) in 2014, and size did not differ between years (t13 = 0.07, P = 0.95), averaging 208.3 ha (SD = 244.9 ha, n = 19 home ranges measured for 12 birds) for the 2 yr of the study. Mean core home-range size (50% MCP) was 78.2 ha (SD =105.9 ha, n = 10) in 2013 and 59.7 ha (SD = 80.7 ha, n = 9) in 2014; core home-range areas also did not differ between years (t17 = −0.46, P = 0.65). Swainson's Hawks did not select habitats in proportion to their availability in 2013 (χ42 = 781.99, P < 0.001) and 2014 (χ40 > 999.99, P < 0.001). In 2013, breeding Swainson's Hawks selected against wetland and grassland habitats and selected for trees as foraging habitats. Similarly, Swainson's Hawks selected against grassland habitats for foraging in 2014. We used known-fate analysis in Program MARK to estimate adult survival during the breeding season. The top-ranked model indicated survival was constant at 0.94 (95% CI = 0.68–0.99) during the breeding season and did not differ between years. Our results suggest that Swainson's Hawks maintain a moderately high degree of breeding-site fidelity and have home ranges smaller than those documented elsewhere, and that their home-range size is influenced positively by the presence of grasslands and negatively by development.

Few studies have evaluated how wetland and forest characteristics influence the prevalence of meningeal worm (Parelaphostrongylus tenuis) infection of deer throughout the grassland biome of central North America. We used previously collected, county-level prevalence data to evaluate associations between habitat characteristics and probability of meningeal worm infection in white-tailed deer (Odocoileus virginianus) across eastern South Dakota, US. The highest-ranked binomial regression model for detecting probability of meningeal worm infection was spring temperature + summer precipitation + percent wetland; weight of evidence (wi=0.71) favored this model over alternative models, though predictive capability was low (Receiver operating characteristic=0.62). Probability of meningeal worm infection increased by 1.3- and 1.6-fold for each 1-cm and 1-C increase in summer precipitation and spring temperature, respectively. Similarly, probability of infection increased 1.2-fold for each 1% increase in wetland habitat. Our findings highlight the importance of wetland habitat in predicting meningeal worm infection across eastern South Dakota. Future research is warranted to evaluate the relationships between climatic conditions (e.g., drought, wet cycles) and deer habitat selection in maintaining P. tenuis along the western boundary of the parasite.

The management and conservation of large carnivores is of worldwide concern and is as much about human values, interactions, and governance as carnivore biology. Susan Clark and Murray Rutherford continue their work on coexisting with large carnivores ( Clark et al. 2005 ) with a new edited volume Large Carnivore Conservation: Integrating Science and Policy in the North American West . Large Carnivore Conservation that expands on the same themes as their previous work with case studies from Arizona to the Yukon. While focusing on the North American West, Clark and Rutherford hope to provide a holistic approach to carnivore management in general.

One key assumption often inferred with using radio-equipped individuals is that the transmitter has no effect on the metric of interest. To evaluate this assumption, we used a known fate model to assess the effect of transmitter type (i.e. tail-mounted or peritoneal implant) on short-term (one year) survival and a joint live—dead recovery model and results from a mark—recapture study to compare long-term (eight years) survival and body condition of ear-tagged only American beavers Castor canadensis to those equipped with radio transmitters in Voyageurs National Park, Minnesota, USA. Short-term (1-year) survival was not influenced by transmitter type (wi = 0.64). Over the 8-year study period, annual survival was similar between transmitter-equipped beavers (tail-mounted and implant transmitters combined; 0.76; 95% CI = 0.45–0.91) versus ear-tagged only (0.78; 95% CI = 0.45–0.93). Additionally, we found no difference in weight gain (t9 = 0.25, p = 0.80) or tail area (t11 = 1.25, p = 0.24) from spring to summer between the two groups. In contrast, winter weight loss (t22 = - 2.03, p = 0.05) and tail area decrease (t30 = - 3.04, p = 0.01) was greater for transmitter-equipped (weight = - 3.09 kg, SE = 0.55; tail area = - 33.71 cm, SE = 4.80) than ear-tagged only (weight = - 1.80 kg, SE = 0.33; tail area = - 12.38 cm, SE = 5.13) beavers. Our results generally support the continued use of transmitters on beavers for estimating demographic parameters, although we recommend additional assessments of transmitter effects under different environmental conditions.