Geology topics

Benjamin Z. Luukkonen

Publications and source records attributed to Benjamin Z. Luukkonen.

3 recordsLinked to original sources

USGS2024

Great Lakes mallard population dynamics

Breeding mallard ( Anas platyrhynchos ) populations in the Great Lakes region (Michigan, Minnesota, Wisconsin, USA) declined by >40% between 2000–2022 based on abundance data collected during spring aerial surveys. Mallards are an important waterfowl species in this region, where an estimated 60–80% of the mallard harvest is composed of locally banded birds. Extensive population monitoring datasets are available for mallards, presenting an opportunity to address complex questions such as estimating productivity at large spatial and temporal scales, identifying the effects of harvest on mallard demography, quantifying mechanisms for harvest compensation, and integrating multiple datasets to quantify the demographic drivers of population change. Our objective was to simultaneously examine factors affecting demographic parameters and their relative contribution to Great Lakes mallard population dynamics. We used 32 years of banding, band recovery, and aerial survey data collected for mallards from Michigan and Wisconsin to develop an integrated population model (IPM). We used age ratios at banding to estimate productivity, band recoveries from hunter-harvested birds to estimate annual survival and cause-specific mortality (i.e., harvest or non-hunting), and modeled abundance using aerial survey and demographic parameter estimates from 1991–2022. The IPM results indicated the decline in Great Lakes mallard abundance was caused by increased non-hunting mortality and a decline in productivity. Productivity varied spatially but temporally declined with the loss of Conservation Reserve Program area. Moreover, our productivity assessment provided evidence of density dependence in reproduction. Non-hunting mortality was 3.5–6.7 times and 1.3–4.2 times greater than harvest mortality for adult and juvenile female mallards, respectively, indicating environmental factors during spring and summer, not harvest, most greatly influenced annual mortality for female mallards. Our IPM reduced uncertainty in the factors affecting Great Lakes mallard population dynamics and indicated management actions that address non-hunting mortality and productivity would be most effective in increasing Great Lakes mallard abundance.

Michigan, Wisconsin↗

USGS2022

Movement of Canada geese in urban and rural areas of Iowa, USA

Temperate-breeding Canada Goose ( Branta canadensis maxima ) abundance has increased to previously unrecorded levels, providing social, ecological, and economic value. However, there are also costs associated with abundant Canada Geese. Although hunter harvest is a valued, sustainable use of Canada Geese, the adaptability of geese to urban areas may result in lower susceptibility of geese to hunters, potentially reducing the contribution of hunter harvest to conflict reduction. Our goal was to compare movement of geese marked in urban and rural areas to assess efficacy of hunter harvest in managing urban goose populations. We marked 71 adult female Canada Geese during brood-rearing with GPS-GSM transmitters in urban (n = 45) and rural (n = 26) locations in Iowa, USA to monitor movement during the 2018-19 and 2019-20 Mississippi Flyway goose hunting season frameworks. We estimated the mean proportion of locations each group was available for hunter harvest and examined factors affecting home range areas using generalized linear mixed models. Additionally, we estimated habitat selection of urban- and rural-marked geese using a step-selection analysis. Urban geese had a lower proportion of locations in areas available to hunters (0.07 [95% CI: 0.04-0.13]) than rural geese (0.56 [95% CI: 0.34-0.76]), but median home range area was similar for each group and decreased in size from autumn to late winter. Canada Geese marked in urban areas were more likely to select developed areas and less likely to select wetlands than rural geese, and they had high selection of agricultural fields within city limits during goose hunting seasons. Although Canada Geese breeding in urban areas may be less available for hunter harvest, movement data show when and where opportunity exists to increase harvest susceptibility. Canada Goose management could require actions in addition to hunter harvest to achieve goals in urban areas.

Iowa↗

USGS2020

Canada goose survival and recovery rates in urban and rural areas of Iowa, USA

Once extirpated from much of their North American range, temperate-breeding Canada geese ( Branta canadensis maxima ) have reached high abundance. As a result, focus has shifted from restoration to managing harvest and addressing human-goose conflict. Conflict persists or is increasing in urban areas throughout the Mississippi Flyway. Managers need more information regarding demographic rates to determine how hunting affects geese breeding in urban areas and what management actions may be required to achieve management goals. We estimated survival, dead recovery, live recapture, and fidelity probabilities using data from 77,872 Canada geese banded in Iowa, USA, during 1999–2019 using Burnham joint live-dead band recovery models. Factors predicted to affect parameters in candidate models included age (juvenile, subadult, adult), banding site (urban, rural), time, trend, harvest regulation index, and winter severity index. We predicted Canada geese banded in urban areas would have higher survival and lower dead recovery rates than geese banded at rural sites. The top model indicated support for age and banding site effects, and trends in survival and recovery rate (Brownie parameterization). Adult survival was similar for urban (0.75; range = 0.60–0.92) and rural (0.75; range = 0.66–0.82) geese and relatively constant across years. Mean juvenile survival was lower in urban (0.74; range = 0.48–0.93) than rural (0.85; range = 0.68–0.92) areas. Survival increased for urban-banded juveniles and recovery rates increased during liberalization of harvest regulations and decreased after regulations stabilized. Recovery rates of subadults increased for the urban and rural groups. Our results suggest Canada geese breeding in urban areas contribute to harvest and specialized regulations can affect these populations. Harvest regulations in place during our analysis may not have reached a threshold required to observe substantial changes in survival. Current human-goose conflict in urban areas suggests survival has not decreased to a level required to completely address conflict via reduction in goose abundance. Managers may consider additional liberalization of harvest regulations and monitoring via banding to determine to what degree hunter harvest contributes to reducing human-goose conflict and what additional management actions will be required to achieve goals. © 2020 The Wildlife Society.

Iowa↗