Patterns of Nutrient Acquisition in Canvasbacks During Spring Migration

Wetlands used by nesting birds have traditionally been considered the only habitats able to influence natality rates. I examined the potential for body reserves (fat, protein, and calcium) acquired on spring staging areas to be used for reproduction. My objectives were to: 1) describe changes in body reserves during spring, 2) examine alternative uses for body reserves in spring migrants, and 3) identify where reserves are acquired. EXxring spring of 1984 and 198? I collected 151 canvasbacks fAvthva valisineria) at 3 staging areas: Navigation Pool 19 of the Mississippi River; Navigation Pools 7, 8, and 9 of the Mississippi River; and in the prairie pothole region of North Dakota. An additional 28 breeding birds were collected in the aspen parklands of Manitoba. Pair status was determined prior to collection of each bird and all birds were aged. \u27The influence of body size on body reserve levels was corrected where needed. Median collection dates occurred just prior to peak canvasback use of each staging area. Masses of ovaries, testes, oviducts, and the largest follicle diameter increased as spring migration phenology advanced. In late migration, ovary and oviduct masses of paired females were greater than in umpired females. Testes masses of paired and unpaired males did not differ. Among sites, patterns of change in body reserves did not parallel patterns of change in reproductive tissue. Calcium mass of males and females did not di\u27 :er among sites regardless of pair status. Protein reserves of paired, breeding females were larger than those of unpaired migrant females. Paired males in North Dakota had higher protein reserves than did jaired males at Pools 7, 8, and 9 or Erickson. Protein reserves of unpaired males did not differ among various staging areas. Fat masses of males and females varied greatly among sites during\u27 migration bur pair status had little influence on them. Paired females airived on breeding areas fat. Males had. more fat and protein than did fen ales during migration but the opposite was true for breeding females. Flight ranges, estimated from measured levels of stored fat, could not allow canvasbacks at any staging area to fly non-stop to breeding areas and arrive fat. Though fat and prctein reserves are acquired during spring, wetland habitats located closa to breeding areas would more .ikely influence a reproductive effort than would habitats located farther away. Other factors such as the energetic costs of migration and fasting through inclement weather may require birds to stop frequently during migration in order to re-acquire lost reserves. Protection of key staging wetlands scattered along the entire migration route may therefore directly or indirectly influence natality rates of canvasbacks

HABITAT SELECTION BY BREEDING SANDHILL CRANES IN CENTRAL WISCONSIN

We used compositional analysis to describe habitat use for a dense population of breeding sandhill cranes (Grus canadensis tabida) in central Wisconsin at 2 spatial scales: selection of home range within a study area and selection of habitats within the home range. Habitat use and home range size were estimated from radio-telemetry data from 12 breeding sandhill crane pairs. Research in Wisconsin that was performed on the landscape level suggests that breeding cranes depend on wetlands and do not select upland habitats. Evaluating habitat selection at different spatial levels, such as during different stages of the breeding season, can better illustrate the hierarchical nature of selection by breeding sandhill cranes. In establishing home ranges, breeding cranes selected wetland habitat over all other land-use categories. Within home ranges, breeding cranes still selected wetland habitat above all other habitat types; however, row crops and tall grass were also important. During daylight hours, habitats that were used consisted primarily of wetland (38.7% ± 4.5 [mean ± 1 SE]), row crop (24.3% ± 5.7), and short crop (14.0% ± 4.6). Home range size as well as the selection of habitat type was not constant during the breeding season. On average, home range size during the post-fledging stage was 3 times greater than pre-fledging stage. Wetlands were used daily (97.4% of all days) throughout the breeding season but for a greater percentage of each day when chicks were small than when large. Wetland accounted for 50.1% of all locations during the pre-fledging stage and for 30.6% of all locations during the post-fledging stage. The knowledge that breeding cranes require emergent wetlands at all spatial and temporal scales, but that the presence of both upland and wetland habitat within a home range is important, provides a greater refinement to the understanding of habitat needs of breeding sandhill cranes in Wisconsin

EVALUATING CHEMICAL DETERRENCE AT TWO SPATIAL SCALES: THE EFFECTIVENESS OF CHEMICAL DETERRENCE FOR SANDHILL CRANES IN CORNFIELDS

From 2006 through 2008, 9,10 anthraquinone (sold as Avitec™) was used as a deterrent on planted corn seed in Minnesota, Wisconsin, and Michigan. ICF conducted field trials in Wisconsin to determine efficacy of Avitec™ to repel sandhill cranes (Grus canadensis) from germinating corn. We assessed crane use at 2 levels: between and within habitats by crane population surveys to determine crane use of fields, and corn density surveys to assess possible damage within fields. In addition, corn seed samples were taken to assess amount of active ingredient on treated corn seeds in the ground. In 2008 the concentrations of Avitec™ on seed obtained from powder treatments (as compared to liquid treated) were generally lower. Where concentration of Avitec™ on the corn seeds was adequate (liquid or powder), it successfully deterred crane herbivory even though crane use of the fields remained high. Non-treated fields had higher damage as crane use increased, whereas treated fields had low or no damage, even with increased crane use. An effective deterrent is a win-win situation for both cranes and farmers. Its use protects a valuable crop while allowing cranes to access critical food items in cultivated fields, which also confers a benefit to the farmer (i.e., consumption of crop pests). Farmers can solve the problem more economically on their own without handling toxic seed treatments. Successful solutions such as this example are critical for advancing wildlife conservation on private lands

TESTING THREE CHEMICALS FOR DETERRING CROP DAMAGE BY CRANES

Damage to planted corn seed by cranes has the potential to cause great economic loss in areas where both intersect. In 2000 the International Crane Foundation (ICF) tested limonene (LIM), methyl anthranilate (MA), and 9,10-anthraquinone (AQ) as possible replacements for the insecticides lindane and diazinon that had been used as deterrents to cranes damaging corn seed and seedlings. LIM, MA, and AQ lowered germination rates (down to 85, 90, and 92%, respectively) as compared to a germination rate of 96% in untreated corn. A 1.0% solution of AQ was effective as a crane deterrent, while LIM and MA were not. Both LIM and MA metabolized in the soil too quickly to be effective during the entire period when corn seedlings were vulnerable to crane herbivory. In 2001, a 0.5% concentration of AQ in 2 different soils (sand and organic) was tested in 2 different time periods (trial 1, 15 May to 14 June; trial 2, 26 June to 7 July 2). The concentration of AQ did not degrade to below effective levels in either soil type or in either time period. In all trials, AQ concentration of 0.5% prevented crane herbivory. Crane response to AQ-treated corn was to continue foraging in fields without damaging the planted crop. We believe AQ is an effective chemical deterrent and will prove useful for preventing crane damage to planted corn

DIFFERENTIAL DETECTION OF TERRITORIAL AND NON-TERRITORIAL GREATER SANDHILL CRANES IN SUMMER

Abundance estimates allow wildlife managers to make informed management decisions, but differential detectability of individuals can lead to biased estimates of abundance. Our objective was to quantify detectability for non-territorial and territorial sandhill cranes (Grus canadensis tabida) during summer. We hypothesized that territorial sandhill cranes would be detected more often than non-territorial cranes. In 2009, 3 wetland areas were surveyed 2 days per week during the nesting season near Briggsville, Wisconsin. We created capture histories for color-marked territorial (n = 52) and color-marked nonterritorial cranes (n = 23) and used the Huggins closed capture model in program MARK to estimate detection probability and abundance for each group. A priori models were developed that explained daily crane detection over the sampling period using distance from road, territorial status, observation event, and time of season as variables. The best approximating model included the variables territorial status and observation event (AICc weight = 0.92). Probability of detection was higher for territorial (0.11, 95% CI = 0.08-0.14) than for non-territorial ( 0.03, 95% CI = 0.01-0.07) sandhill cranes. In subsequent observation events, detection probability almost doubled to 0.18 (95% CI = 0.17-0.20) for territorial cranes, and almost tripled to 0.11 (95% CI = 0.09-0.14) for non-territorial cranes. Potential reasons for differential detection during subsequent observations include differing degrees of movement by birds and/or an observer effect in which the ability to observe birds or the perception by technicians of birds increased over time

TIMING OF FAMILY DISSOCIATION DOES NOT AFFECT LONG-TERM SURVIVAL ESTIMATES OF SANDHILL CRANE CHICKS

Sandhill crane (Grus canadensis) chicks depend on their parents beyond fledging, but timing of chick separation from their parents has rarely been quantified and reported. We color-banded and radio-tagged sandhill crane chicks on known natal territories in south-central Wisconsin and monitored family groups to determine age of chick independence. Using a Cormack-Jolly-Seber open population model in program MARK, we estimated survival for chicks that dissociated from their parents prior to fall migration, over winter (including migration), and following spring migration. Of 96 chicks with a known timing of dissociation from their parents, 11 (12%) became independent from their parents in the fall before migration during their hatch year, 76 (79%) became independent over winter, and 9 (9%) returned from spring migration with their parents and then became independent. Mean age (± 1 SE) at independence varied from 146 ± 7 days (fall) to 248 ± 14 days (off breeding areas) to 335 ± 11 days (spring). Season of chick dissociation did not affect whether a chick was philopatric or dispersive in its first year. Lifetime survival estimates were high (92%) and did not generally differ based on marking scheme (radio-tagged vs. color-banded), sex (male or female), or timing of dissociation (fall, off breeding areas, or spring). Chicks that did not migrate with their parents likely learned migratory routes and behaviors from conspecifics. More research on interactions between parents, their offspring, and other conspecifics off breeding areas (winter and migratory stopover areas) could provide insight into dissociation patterns and the mechanism of separation

HABITAT SELECTION BY BREEDING SANDHILL CRANES IN CENTRAL WISCONSIN

We used compositional analysis to describe habitat use for a dense population of breeding sandhill cranes (Grus canadensis tabida) in central Wisconsin at 2 spatial scales: selection of home range within a study area and selection of habitats within the home range. Habitat use and home range size were estimated from radio-telemetry data from 12 breeding sandhill crane pairs. Research in Wisconsin that was performed on the landscape level suggests that breeding cranes depend on wetlands and do not select upland habitats. Evaluating habitat selection at different spatial levels, such as during different stages of the breeding season, can better illustrate the hierarchical nature of selection by breeding sandhill cranes. In establishing home ranges, breeding cranes selected wetland habitat over all other land-use categories. Within home ranges, breeding cranes still selected wetland habitat above all other habitat types; however, row crops and tall grass were also important. During daylight hours, habitats that were used consisted primarily of wetland (38.7% ± 4.5 [mean ± 1 SE]), row crop (24.3% ± 5.7), and short crop (14.0% ± 4.6). Home range size as well as the selection of habitat type was not constant during the breeding season. On average, home range size during the post-fledging stage was 3 times greater than pre-fledging stage. Wetlands were used daily (97.4% of all days) throughout the breeding season but for a greater percentage of each day when chicks were small than when large. Wetland accounted for 50.1% of all locations during the pre-fledging stage and for 30.6% of all locations during the post-fledging stage. The knowledge that breeding cranes require emergent wetlands at all spatial and temporal scales, but that the presence of both upland and wetland habitat within a home range is important, provides a greater refinement to the understanding of habitat needs of breeding sandhill cranes in Wisconsin

EFFECTIVE AND SUSTAINABLE PREVENTION OF AVIAN DAMAGE TO PLANTED SEEDS THROUGH SEED TREATMENT

Several species of cranes and other wildlife have recovered from low populations because, in part, they have adapted to resources found in agricultural environments. If future conservation strategies are to succeed in areas dominated by agricultural use, we must develop sustainable models that solve crop damage problems that are caused by expanding wildlife populations. Using crane damage to planted seed as an example, we propose 1 such model of sustainable crop damage prevention. The deterrent, 9,10-anthraquinone (AQ), is a natural product produced by plants, in part to control bird frugivory, and induces gastro-intestinal distress (temporarily sickens an individual) in sandhill cranes (Grus canadensis) as well as other bird species. AQ is an effective deterrent because it induces a physiological response at first and is then accompanied by a conditioned avoidance. Yet, AQ is not toxic to birds nor are birds likely to habituate to the deterrent. Seed repellents cause birds to avoid treated foods among several possible items found within the same field. Other, more traditional, crop damage repellents (e.g., propane cannons) operate by moving birds among fields within home ranges. Excluding preferred habitats such as cornfields increases the risk that birds will habituate to deployed damage solutions. AQ products have adapted to a diverse farm environment and cost less than 3% of total planting costs. They were applied to prevent crane damage on planted corn for more than 67,000 ha in the Midwest during 2018 and can be deployed at whatever spatial scale that damage severity warrants. Our model using AQ as a seed treatment to prevent crane damage to germinating corn has been applied to pheasants (Phasianus colchicus) and blackbirds (Icteridae) as well as in rice and sunflower crops. As such, this model presents a sustainable approach that arises from solutions that allow agriculture and wildlife to co-exist

INFLUENCE OF LANDSCAPE FEATURES OF WETLANDS ON NESTING PATTERNS OF SANDHILL CRANES IN CENTRAL WISCONSIN

We studied the relationship between landscape features and nesting patterns of greater sandhill cranes (Grus canadensis tabida) in central Wisconsin for 3 years. Our study covered 9,840 ha, including about 50% agricultural fields, 20% forest, and 20% wetlands. We analyzed landscape features and nesting patterns at the wetland complex level. Landscape features included size, shape, and type of cover for each wetland complex. Nesting patterns included nesting density and the spatial pattern of the nest locations in a wetland among years. Nest density varied among wetland complexes and years. Mean nest densities in wetlands surveyed were 0.037, 0.033, and 0.047 nests/ha in 2001, 2002, and 2003, respectively. Nest density in individual wetlands varied from year to year, from 0.00 to 11.24 nests/ha. Mid-sized wetlands (80-120 ha) had similar means, around 0.05 nests/ha, and had smaller variations in nest density among years in comparison with small wetlands. Spatial point pattern analysis showed that the spatial pattern of nest locations in the wetlands was not always clustered. Mean distance between the two closest nests within single wetlands within a year was 227 m (11-666 m, SD = 163 m). The distance was usually around 120 m for a mid-sized wetland

Revisiting the Historic Distribution and Habitats of the Whooping Crane

Understanding the historic range and habitats of an endangered species can assist in conservation and reintroduction efforts for that species. Individuals reintroduced into a species’ historic core range have a higher survival rate compared to individuals introduced near the periphery or outside the historic range (Falk and Olwell, 1992; Griffith et al., 1989). Individuals on the periphery of a species’ range tend to occupy less favorable habitats and have lower and more variable densities than those near the core of their range (Brown, 1984; Brown et al., 1995, 1996). Such conclusions, however, presume that historic habitats have not changed since a species was extirpated from core areas – a difficult assumption for many areas, and particularly for wetland habitat (Prince, 1997). Many endangered species persist only on the periphery of their historic range because of habitat loss or modification in their core range (Channell and Lomolino, 2000), which can bias our understanding of the species’ habitat preferences. Further, habitat models based on locations where species persist necessarily emphasize local conditions rather than historical conditions (Kuemmerle et al., 2011). For example, habitat models for the European bison (Bison bonasus) suggested it was a woodland species, but assessment of the bison’s historic range indicated it preferred mosaictype landscapes and had a more eastern and northern distribution than previously reported (Kuemmerle et al., 2011, 2012). Hence, accurate determination of the historic range and habitat conditions for endangered species can improve our understanding of their ecology and assist in conservation and reintroduction efforts. Examining the historic range from an ecological perspective can also help identify where appropriate habitat still exists that could sustain a population