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Kevin P. Kenow

Publications and source records attributed to Kevin P. Kenow.

At least 19 recordsLinked to original sources
USGS2026

Restoration of Gavia immer (common loon) in Minnesota—2025 annual report

In cooperation with the Minnesota Department of Natural Resources, the U.S. Geological Survey monitored 98 Gavia immer (common loon) focal territories and 43 nonfocal territories in north-central Minnesota in 2025. Focal territories are those sampling units from which study inferences can be made. Nonfocal territories were adjacent to focal territories and were observed to monitor common loon dynamics across an entire waterbody. In collaboration with lake associations and private citizens, we deployed 44 artificial nesting platforms to 44 focal territories, called treatment territories. Territorial surveys to monitor occupancy, nesting, and chick survival were completed between April 27 and August 14, 2025. We attempted to visit each focal and nonfocal territory once per week. At least 1 nest attempt was observed in 40 of 54 control territories and 37 of 44 treatment territories. In treatment territories, 14 nests were on an artificial nesting platform, and the remaining nests were on natural substrates. Chicks or other evidence of hatching were observed in 20 of 54 control territories (37 percent) and 28 of 44 treatment territories (64 percent). Twelve of those successful nests in treatment territories were on artificial nesting platforms.

Minnesota↗
USGS2026

Harvest of long-tailed ducks from an important hunting location on Lake Michigan

Annual waterfowl harvest in North America is estimated through a collaborative and strategic process, with federal harvest surveys the primary method of estimation. Sea duck hunters participating in federal harvest surveys represent a small proportion of the overall waterfowl hunting population, limiting the utility of harvest estimates for sea ducks. The long-tailed duck ( Clangula hyemalis ) is one such species. To partially address the paucity of long-tailed duck harvest survey information, we conducted in-person hunter surveys from 1 November through 4 December 2016 at a boat launch in Two Rivers, Wisconsin, USA (Lake Michigan), an important area for long-tailed duck harvest within the state. Hunters were present on 15 of 21 survey days, and we surveyed occupants of 62 individual hunting boats on 127 occasions. Long-tailed ducks were the most common (97%) of the 1,431 sea ducks reported harvested by hunters. Hunter harvest of long-tailed ducks averaged 3.8 (95% CI = 3.4, 4.1; range = 0–6) long-tailed ducks/hunter/day. We used count models to evaluate the effects of environmental variables on hunter participation and harvest of long-tailed ducks. Wave height was the most influential predictor variable for hunter participation; an information criterion-based best model (wave height + temperature) indicated that hunter participation decreased by 91.9% (95% CI = 79.3–97.1%) for each 1-m increase in wave height. Long-tailed duck harvest was positively associated with air temperature; the relationship indicated a 9.5% (95% CI = 6.2–12.9%) increase in long-tailed duck harvest with each degree increase in temperature. Our results contribute to the understanding of waterfowl hunter participation, hunter preferences, and harvest on Lake Michigan and can inform managers as they assess regulatory frameworks for sea duck hunting.

Wisconsin↗
USGS2025

Restoration of Gavia immer (common loon) in Minnesota—2024 annual report

In cooperation with the Minnesota Department of Natural Resources, the U.S. Geological Survey monitored 98 common loon ( Gavia immer ) focal territories and an additional 37 nonfocal territories in 2024 across 53 study lakes in Minnesota. Focal territories were those territories from which study inferences will be made, whereas nonfocal territories were observed to monitor common loon dynamics in territories adjacent to focal territories. In collaboration with lake associations and private citizens, we deployed 44 artificial nesting platforms within 44 treatment territories, and the remaining 54 focal territories were controls. We completed territorial surveys from April 29 to August 9, 2024, to evaluate occupancy, nest success, and chick survival. We attempted to visit each territory once a week. At least one nest attempt was observed in 41 of 54 control territories. Precisely one nest attempt was observed in 30 control territories, two nest attempts (first attempts failed) were observed in 9 control territories, and three nest attempts (first and second attempts failed) were observed in 2 control territories. At least one nest attempt was observed in 33 of 44 treatment territories. Precisely one nest attempt was observed in 25 treatment territories, two nest attempts (first attempts failed) were observed in 7 treatment territories, and three nest attempts (first and second attempts failed) were observed in 1 treatment territory. In treatment territories, 8 nests were on an artificial nesting platform; the remaining nest locations were natural. Chicks or other evidence of hatching were observed in 26 of 54 (48.1 percent) control territories and 21 of 44 (47.7 percent) treatment territories, with 7 of those successful treatment nests on an artificial nesting platform. This report includes no formal analysis, but we plan to analyze data after collection of all field data in subsequent years.

Minnesota↗
USGS2024

Restoration of common loon (Gavia immer) in Minnesota—2023 annual report

The Deepwater Horizon mobile drilling platform exploded on April 20, 2010. The resulting massive oil spill injured natural resources in the Gulf of Mexico, including wintering common loons ( Gavia immer ). We report on activities completed under the “Restoration of Common Loons in Minnesota” project in calendar year 2023, which was funded by the Open Ocean Trustee Implementation Group. In 2022, a subset of monitored breeding territories was identified as focal territories, which are sampling units for the study. The U.S. Geological Survey, in cooperation with the Minnesota Department of Natural Resources, monitored 98 common loon focal territories and an additional 43 nonfocal territories in 2023 across 56 study lakes in Minnesota. We collaborated with lake associations and private citizens to deploy 42 artificial nesting platforms within 44 focal treatment territories. The remaining 54 focal territories were controls. Territorial surveys were completed from May 8 to August 11, 2023, to evaluate occupancy, nest success, and chick survival. At least one nest attempt was observed in 31 of 44 treatment territories and a second nest attempt was observed after a failed initial attempt in 6 treatment territories. However, only one nest was on an artificial nesting platform in a treatment territory; the remaining nest locations were natural. At least one nest attempt was observed in 37 of 54 control territories, and a second nest attempt was observed after a failed initial attempt in 5 control territories. Chicks or other evidence of hatching were observed in 17 of 54 control territories and 17 of 44 treatment territories, with 1 of those successful treatment nests occurring on an artificial nesting platform. This report includes no formal analysis, but we plan to analyze data after collection of all field data in subsequent years.

Minnesota↗
USGS2023

Restoration of Gavia immer (common loon) in Minnesota—2022 annual report

The explosion of the Deepwater Horizon mobile drilling platform on April 20, 2010, caused a massive oil spill and injury to natural resources in the Gulf of Mexico. Gavia immer (common loon) were negatively affected from the spill. The Open Ocean Trustee Implementation Group funded the project “Restoration of Common Loons in Minnesota” to restore common loons lost to the spill. Here, we report on activities conducted for this project in an eight-county region in Minnesota in calendar year 2022. We identified a subset of territories that were monitored in 2021 as focal territories ( n =99) from which multiyear study inferences can ultimately be made. We monitored nonfocal territories on all study lakes as well. We conducted surveys from May 9 to August 12, 2022. At least 1 nest attempt was observed in 68 of 99 focal territories, and a second nest attempt after a failed initial attempt was observed in 17 focal territories. Chicks or other evidence of hatching was observed in 33 of 99 territories. Data collected in 2021 and 2022 for this project are presented in a U.S. Geological Survey data release ( https://doi.org/10.5066/P9LA536E ). We present no formal data analysis in this report.

Minnesota↗
USGS2023

The relative importance of cisco (Coregonus artedi) in the diets of common loons (Gavia immer) among a set of cisco refuge lakes in Minnesota

Common loon ( Gavia immer (Brünnich, 1764)) foraging patterns and the relative importance of cisco ( Coregonus artedi Lesueur, 1818) in the diets of loons were evaluated for the Whitefish Chain of Lakes, a set of coldwater cisco refuge lakes in Minnesota, USA. Environmental DNA metabarcoding of loon fecal samples detected 15 fish species. Yellow perch ( Perca flavescens (Mitchill, 1814)), mimic shiner ( Notropis volucellus (Cope, 1865)), and cisco were the most prominent prey detected across the study lakes. We observed a shift in fish species consumed, with increases in detections of mimic shiner and cisco DNA among loon fecal samples collected in August and September. In some locations, suitable oxythermal habitat became restricted throughout the summer, forcing cisco into surface waters, which potentially increased their vulnerability to loon predation. Conversely, large foraging aggregations of loons were observed during late summer through fall at locations with ample oxythermal habitat and abundant cisco populations. We hypothesize that cisco were sought by loons as a high-calorie prey resource prior to migration. Conservation efforts directed at preserving water quality in important cisco refuge lakes are likely to benefit common loons through enhancement of both the forage base, for resident and migrating birds, and breeding habitat suitability.

Minnesota↗
USGS2023

Dive characteristics of Common Loons wintering in the Gulf of Mexico and off the southern U.S. Atlantic coast

Common Loons ( Gavia immer ) winter primarily in marine coastal areas and utilize a forage base that is poorly defined, especially for offshore areas. Information on dive activity is needed for describing foraging strategies and for inferring prey distribution. Archival geolocator tags were used to determine the wintering locations and dive characteristics of adult Common Loons captured and marked on breeding lakes in Minnesota, Wisconsin, and the Upper Peninsula of Michigan. Among loons that completed fall migration, most wintered in the Gulf of Mexico, with smaller proportions wintering off the southern Atlantic Coast or impoundments in the southeastern United States. Adult Common Loons tended to occupy offshore areas of the Gulf of Mexico and the Atlantic Ocean and, on average, spent about 60% of daylight hours foraging. Dive depths were as deep as 50 m (Gulf of Mexico) and dive characteristics indicated that loons were primarily foraging on benthic prey. Total dive duration, time at maximum depth, and post-dive surface intervals increased with dive depths among wintering Common Loons. Our results are expected to contribute to the understanding of the wintering ecology of Common Loons and be useful in informing regional and national conservation planning efforts.

Journal of Field Ornithology↗
USGS2022

Restoration of Gavia immer (common loon) in Minnesota—2021 annual report

The Deepwater Horizon oil spill caused extensive injury to natural resources in the Gulf of Mexico, and Gavia immer (common loon) were negatively affected from the spill. The Open Ocean Trustee Implementation Group funded the project Restoration of Common Loons in Minnesota to restore common loons lost to the spill. In 2020–21, priority lakes in an eight-county region in north-central Minnesota were identified to focus project activities. In 2021, surveys on these lakes were started to monitor common loon territory occupancy, nest success, and chick survival. We surveyed 62 lakes and identified 110 common loon territories that will be included in the project. At least 1 nest attempt was observed in 78 of 110 territories, and a second nest attempt was observed in 23 territories. A third nest attempt was observed in one territory. Successful nesting was observed in 32 of 110 territories. We present no formal data analysis and plan to analyze the data after the collection of all field data in subsequent years.

Minnesota↗
USGS2021

Migration patterns and wintering distribution of common loons breeding in the Upper Midwest

Identification of geographic linkages among breeding, migratory and wintering common loon Gavia immer populations is needed to inform regional and national conservation planning efforts and compensation of loons lost during marine oil spill events. Satellite telemetry and archival geolocator tags were used to determine the migration patterns and wintering locations of breeding adult and young of the year juvenile common loons captured and marked on lakes in Minnesota, Wisconsin and Michigan. Adult loons typically traveled from breeding lakes, often via larger staging lakes, to the Great Lakes (primarily Lake Michigan) and then on to wintering areas. Most radiomarked juvenile common loons utilized natal lakes or local lakes through mid-November. Subsequently, the first fall migration of juvenile loons was generally initiated later, and more direct and quicker to wintering areas relative to adults. Among adult (n = 103) and juvenile (n = 23) loons that completed fall migration, most wintered in the Gulf of Mexico (GOM), with smaller proportions wintering off the southern Atlantic Coast or impoundments in the southeastern United States. Spring migration of adults to breeding lakes was less prolonged than fall migration, with adult male loons tending to depart wintering areas earlier than adult females. Juvenile common loons migrated during their first spring from wintering sites in the GOM to summer in the Gulf of St Lawrence/Nova Scotia Coastal region. Juvenile mortality was largely linked to parasitic infection and emaciation; spring appeared to be a survival bottleneck among juvenile loons monitored in our study. Our results identify several areas where common loon conservation efforts could be directed to protect key habitats and minimize stressors during the non-breeding period.

Michigan, Minnesota, Wisconsin↗
USGS2020

Assessing year‐round habitat use by migratory sea ducks in a multi‐species context reveals seasonal variation in habitat selection and partitioning

Long‐distance migration presents complex conservation challenges, and migratory species often experience shortfalls in conservation due to the difficulty of identifying important locations and resources throughout the annual cycle. In order to prioritize habitats for conservation of migratory wildlife, it is necessary to understand how habitat needs change throughout the annual cycle, as well as to identify key habitat sites and features that concentrate large numbers of individuals and species. Among long‐distance migrants, sea ducks have particularly complex migratory patterns, which often include distinct post‐breeding molt sites as well as breeding, staging and wintering locations. Using a large set of individual tracking data (n = 476 individuals) from five species of sea ducks in eastern North America, we evaluated multi‐species habitat suitability and partitioning across the breeding, post‐breeding migration and molt, wintering and pre‐breeding migration seasons. During breeding, species generally occupied distinct habitat areas, with the highest levels of multi‐species overlap occurring in the Barrenlands west of Hudson Bay. Species generally preferred flatter areas closer to lakes with lower maximum temperatures relative to average conditions, but varied in distance to shore, elevation and precipitation. During non‐breeding, species overlapped extensively during winter but diverged during migration. All species preferred shallow‐water, nearshore habitats with high productivity, but varied in their relationships to salinity, temperature and bottom slope. Sea ducks selected most strongly for preferred habitats during post‐breeding migration, with high partitioning among species; however, both selection and partitioning were weaker during pre‐breeding migration. The addition of tidal current velocity, aquatic vegetation presence and bottom substrate improved non‐breeding habitat models where available. Our results highlight the utility of multi‐species, annual‐cycle habitat assessments in identifying key habitat features and periods of vulnerability in order to optimize conservation strategies for migratory wildlife.

Land Surrounding Hudson Bay↗
USGS2020

Implanted satellite transmitters affect sea duck movement patterns at short- and long-term time scales

Studies of the effects of transmitters on wildlife often focus on survival. However, non-lethal behavioral changes resulting from radiomarking have the potential to affect inferences from telemetry data and may vary based on individual and environmental characteristics. We used a long-term, multi-species tracking study of sea ducks to assess behavioral patterns at multiple temporal scales following implantation of intracoelomic satellite transmitters. We applied state-space models to assess short-term behavioral patterns in individuals with implanted satellite transmitters, as well as comparing breeding site attendance and migratory phenology across multiple years after capture. In the short term, our results suggest an increase in dispersive behavior immediately following capture and transmitter implantation; however, behavior returned to seasonally-average patterns within approximately five days after release. Over multiple years, we found that breeding site attendance by both males and females was depressed during the first breeding season after radiomarking relative to subsequent years, with larger relative decreases in breeding site attendance among males than females. We also found that spring migration occurred later in the first year after radiomarking than in subsequent years. Across all behavioral effects, the severity of behavioral change often varied by species, sex, age, and capture season, suggesting heterogeneity in individual sensitivity. We conclude that, although individuals appear to adjust relatively quickly (i.e., within one week) to implanted satellite transmitters, changes in breeding phenology may occur over the longer term and should be considered when analyzing and reporting telemetry data.

Condor↗
USGS2019

Synthesis of maternal transfer of mercury in birds: Implications for altered toxicity risk

Maternal transfer is the predominant route of methylmercury (MeHg) exposure to offspring. We reviewed and synthesized published and unpublished data on maternal transfer of MeHg in birds. Using paired samples of females’ blood (n=564) and their eggs (n=1814) from 26 bird species in 6 taxonomic orders, we conducted a meta-analysis to evaluate whether maternal transfer of MeHg to eggs differed among species and caused differential toxicity risk to embryos. Total mercury (THg) concentrations in eggs increased with maternal blood THg concentrations; however, the proportion of THg transferred from females to their eggs differed among bird taxa and with maternal THg exposure. Specifically, a smaller proportion of maternal THg was transferred to eggs with increasing female THg concentrations. Additionally, the proportion of THg that was transferred to eggs at the same maternal blood THg concentration differed among taxonomic orders, with waterfowl (Anseriformes) transferring up to 382% more THg into their eggs than songbirds (Passeriformes). We provide equations to predict THg concentrations in eggs using female blood THg concentrations, and vice versa, which may help translate toxicity benchmarks across tissues and life stages. Our results indicate that toxicity risk of MeHg can vary among bird taxa due to differences in the maternal transfer of MeHg to offspring.

Environmental Science & Technology↗
USGS2019

A comparative analysis of common methods to identify waterbird hotspots

1. Hotspot analysis is a commonly used method in ecology and conservation to identify areas of high biodiversity or conservation concern. However, delineating and mapping hotspots is subjective and various approaches can lead to different conclusions with regard to the classification of particular areas as hotspots, complicating long-term conservation planning and implementation efforts. 2. We present a comparative analysis of recent approaches for identifying waterbird hotspots, with the goal of developing insights about the appropriate use of these methods. We selected four commonly used measures to identify persistent areas of high use: kernel density estimation, Getis-Ord Gi*, hotspot persistence, and hotspots conditional on presence, which represent the range of quantitative hotspot estimation approaches used in waterbird analyses. We applied each of the methods to aerial survey waterbird count data collected in the Great Lakes from 2012-2014 using a 5 km2 grid. For each approach, we identified areas of high use for seven species/species groups and then compared the results across all methods. 3. Our results indicate that formal hotspot analysis frameworks do not always lead to the same conclusions. The kernel density and Getis-Ord Gi* methods yielded the most similar results across all species analyzed. We found that these two models can differ substantially from the hotspot persistence and hotspots conditional on presence estimation approaches, which were not consistently similar to one another. The hotspot persistence approach differed most significantly from the other methods but is the only method to explicitly account for temporal variation. 4. We recommend considering the ecological question and scale of any conservation or management activities prior to designing survey methodologies. Deciding the appropriate definition and scale for analysis is critical for interpretation of hotspot analysis results. Combining methods using an integrative approach, either within a single analysis or post-hoc, could lead to greater consistency in the identification of waterbird hotspots.

Lake Erie, Lake Huron, Lake Michigan↗
USGS2019

Spatially explicit network analysis reveals multi-species annual cycle movement patterns of sea ducks

Conservation of long-distance migratory species poses unique challenges. Migratory connectivity—that is, the extent to which groupings of individuals at breeding sites are maintained in wintering areas—is frequently used to evaluate population structure and assess use of key habitat areas. However, for species with complex or variable annual-cycle movements, this traditional bimodal framework of migratory connectivity may be overly simplistic. Like many other waterfowl, sea ducks often travel to specific pre- and post-breeding sites outside their nesting and wintering areas to prepare for migration and, in some cases, molt their flight feathers. These additional molt migrations may play a key role in population structure, but are not included in traditional models of migratory connectivity. Network analysis, which applies graph theory to assess landscape connectivity, offers a powerful tool for quantitatively assessing the contributions of different sites used throughout the annual cycle to complex spatial networks. We collected satellite telemetry data on annual cycle movements of over 500 individual sea ducks of five species from throughout eastern North America and the Great Lakes. From these data, we constructed a multi-species network model of migratory patterns and site use over the course of the breeding, molting, wintering, and migration periods. Our results highlight inter- and intra-specific differences in the patterns and complexity of annual-cycle movement patterns, including the central importance of staging and molting sites in James Bay and the St. Lawrence River to multi-species habitat connectivity. We also discuss potential applications of network migration models to conservation prioritization, identification of population units, and integrating different data streams.

Ecological Applications↗
USGS2018

Patterns of mercury and selenium exposure in Minnesota common loons

Common loons ( Gavia immer ) are at risk of elevated dietary mercury (Hg) exposure in portions of their breeding range. To assess the level of risk among loons in Minnesota (USA), we investigated loon blood Hg concentrations in breeding lakes across Minnesota. Loon blood Hg concentrations were regressed on predicted Hg concentrations in standardized 12‐cm whole‐organism yellow perch ( Perca flavescens ), based on fish Hg records from Minnesota lakes, using the US Geological Survey National Descriptive Model for Mercury in Fish. A linear model, incorporating common loon sex, age, body mass, and log‐transformed standardized perch Hg concentration representative of each study lake, was associated with 83% of the variability in observed common loon blood Hg concentrations. Loon blood Hg concentration was positively related to standardized perch Hg concentrations; juvenile loons had lower blood Hg concentrations than adult females, and blood Hg concentrations of juveniles increased with body mass. Blood Hg concentrations of all adult common loons and associated standardized prey Hg for all loon capture lakes included in the study were well below proposed thresholds for adverse effects on loon behavior, physiology, survival, and reproductive success. The fish Hg modeling approach provided insights into spatial patterns of dietary Hg exposure risk to common loons across Minnesota. We also determined that loon blood selenium (Se) concentrations were positively correlated with Hg concentration. Average common loon blood Se concentrations exceeded the published provisional threshold.

Environmental Toxicology and Chemistry↗
USGS2018

Flooding tolerance of Sagittaria latifolia and Sagittaria rigida under controlled laboratory conditions

Pool‐scale growing‐season water‐level reductions (drawdowns) have been implemented on the Upper Mississippi River in an effort to improve fish and wildlife habitat. Aquatic vegetation is a key habitat component, with perennial emergent species, such as Sagittaria latifolia and Sagittaria rigida , especially important. River managers have assumed the need for continuous drawdown during the growing season with limited reflooding and used this guidance in assessing the potential for an ecologically successful drawdown. However, information on the effects of growing‐season flooding episodes on survival and growth of Sagittaria is limited. To assess the flooding tolerance of S. latifolia and S. rigida , we evaluated multiple levels of timing, duration, and depth on survival and productivity of plants. Plants were produced from S. latifolia and S. rigida seeds and S. latifolia tubers; all were reared under moist‐soil or shallow‐flooded rearing conditions. Mortality of plants was low (2%) among plants from large tubers, low (7%) among seedlings (and largely associated with early flooding treatments), and modest (11%) among plants from small tubers (with no clear effects of inundation). Flooding treatments generally had a positive effect on biomass production from seedlings, particularly when treatments occurred early, were relatively shallow, and were short in duration. There were no clear effects of depth, duration, or timing components of flooding treatments on plant biomass arising from tubers. This experiment indicates that S. latifolia and S. rigida are relatively tolerant of flooding events during the growing season and may actually benefit from some level of inundation.

River Research and Applications↗
USGS2018

Distribution and foraging patterns of common loons on Lake Michigan with implications for exposure to type E avian botulism

Common loons ( Gavia immer ) staging on the Great Lakes during fall migration are at risk to episodic outbreaks of type E botulism. Information on distribution, foraging patterns, and exposure routes of loons are needed for understanding the physical and ecological factors that contribute to avian botulism outbreaks. Aerial surveys were conducted to document the spatiotemporal distribution of common loons on Lake Michigan during falls 2011–2013. In addition, satellite telemetry and archival geolocator tags were used to determine the distribution and foraging patterns of individual common loons while using Lake Michigan during fall migration. Common loon distribution observed during aerial surveys and movements of individual radiomarked and/or geotagged loons suggest a seasonal pattern of use, with early fall use of Green Bay and northern Lake Michigan followed by a shift in distribution to southern Lake Michigan before moving on to wintering areas. Common loons tended to occupy offshore areas of Lake Michigan and, on average, spent the majority of daylight hours foraging. Dive depths were as deep as 60 m and dive characteristics suggested that loons were primarily foraging on benthic prey. A recent study concluded that round gobies ( Neogobius melanostomus ) are an important prey item of common loons and may be involved in transmission of botulinum neurotoxin type E. Loon distribution coincides with the distribution of dreissenid mussel biomass, an important food resource for round gobies. Our observations support speculation that energy transfer to higher trophic levels via gobies may occur in deep-water habitats, along with transfer of botulinum neurotoxin.

Michigan, Minnesota, Wisconsin↗