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D.S. Gilmer

Publications and source records attributed to D.S. Gilmer.

At least 37 records · Page 2Linked to original sources
USGS1981

Characteristics of central North Dakota wetlands determined from sample aerial photographs and ground study

Wetland characteristics were assessed from a systematic sample of 66 plots, 3.22 km2 each, drawn from a 10,041-km2 study area in central North Dakota. Each plot was visited once and 8 sets of aerial photographs were obtained in 3 years. Density of wetland basins was 11.00 ha/km2, and area averaged 9.7 ha/km2. Seasonal and temporary wetlands were most abundant; semipermanent wetlands occupied the greatest area. Basin size was positively correlated with water permanence. Discriminant function analysis based on size and an index to wetness derived from photographs misclassified 33% of the wetland basins. Forty percent of the wetlands were tilled. Photography of sample plots is potentially useful for determining number of basins and wetland area, but precise classification of plant communities in this region would require ground study.

Wildlife Society Bulletin↗
USGS1978

Natural cavities used by wood ducks in north-central Minnesota

Radio telemetry was used to locate 31 wood duck ( Aix sponsa ) nest cavity sites in 16 forest stands. Stands were of 2 types: (1) mature (mean = 107 years) northern hardwoods (10 nest sites), and (2) mature (mean = 68 years) quaking aspen ( Populus tremuloides ) (21 nest sites). Aspen was the most important cavity-producing tree used by wood ducks and accounted for 57 percent of 28 cavities inspected. In stands used by wood ducks, the average density of suitable cavities was about 4 per hectare. Trees containing nests were closer to water areas (P < 0.05) and the nearest forest canopy openings (P < 0.01) than was a random sample of trees from the same stands. A significant (P < 0.005) relationship existed between the orientation of the cavity entrance and the nearest canopy opening. Potential wood duck cavities usually were clustered within a stand rather than randomly distributed. Selection of trees by woodpeckers for nest hole construction probably influenced the availability of cavities used by wood ducks. A plan for managing forests to benefit wood ducks and other wildlife dependent on old-growth timber is discussed.

Minnesota↗
USGS1978

Use of Landsat data to assess waterfowl habitat quality

This report is a discussion of the feasibility of using Landsat data to generate information of value for effective management of migratory waterfowl. Effective management of waterfowl includes regulating waterfowl populations through hunting regulations and habitat management. This report examines the ability to analyze annual production by monitoring the number of breeding and brood ponds that are present, and the ability to assess waterfowl habitat based on the various relationships between ponds and the surrounding upland terrain types. The basic conclusions of this report are that: 1) Landsat data can be used to improve estimates of pond numbers which may be correlated with duck production; and 2) Landsat data can be used to generate information on terrain types which subsequently can be used to assess relative waterfowl habitat quality.

Report↗
USGS1977

Post-breeding activities of mallards and wood ducks in north-central Minnesota

We used radio telemetry to monitor the post-breeding activities of 129 mallards ( Anas platyrhynchos ) and 118 wood ducks ( Aix sponsa ) on a 932-km2 area in north-central Minnesota from 1968 to 1974. Upon completion of breeding activities and before the flightless period, all mallard drakes departed the area; this exodus peaked during early June. Of the non-brood hens 8 of 23 remained on the area, whereas 26 of 51 of the hens raising broods spent the flightless period on their breeding areas. Thirty-nine percent of the mallard hens on the area in the spring were present at the beginning of their flightless period. Fifty percent of the drake wood ducks and 41 percent of the hens left the breeding area before flightlessness. Their timing was similar to that of mallards. The flightless period began in mid-June for wood duck drakes and lasted into early October for some mallard hens. All late molting mallard and wood duck hens reared broods that same year. A minimum of 35 percent of the spring mallard hens remained on the area at the beginning of hunting season (early October). About 17 percent of the wood duck males and 42 percent of the females breeding locally remained on the area until hunting began. Eleven of 51 mallards and 4 of 25 wood ducks that reared broods were killed on the study area compared with 2 of 23 for non-brood mallards and 1 of 20 for non-brood wood duck hens. Principal habitats used by post-breeding mallards were bays of large lakes and river marshes. Wood ducks tended to use similar habitat but also frequented small woodland ponds. During the flightless period both species remained mostly in areas with abundant emergent cover.

Journal of Wildlife Management↗
USGS1976

Utilization of satellite data for inventorying prairie ponds and lakes

By using data acquired by LANDSAT-1 (formerly ERTS- 1), studies were conducted in extracting information necessary for formulating management decisions relating to migratory waterfowl. Management decisions are based in part on an assessment ofhabitat characteristics, specifically numbers, distribution, and quality of ponds and lakes in the prime breeding range. This paper reports on a study concerned with mapping open surface water features in the glaciated prairies. Emphasis was placed on the recognition of these features based upon water's uniquely low radiance in a single nearinfrared waveband. The results of this recognition were thematic maps and statistics relating to open surface water. In a related effort, the added information content of multiple spectral wavebands was used for discriminating surface water at a level of detail finer than the virtual resolution of the data. The basic theory of this technique and some preliminary results are described.

Photogrammetric Engineering and Remote Sensing↗
USGS1975

Habitat use and home range of mallards breeding in Minnesota

Telemetry techniques were used to study habitat use and home range of 12 drake and 12 hen mallards ( Anas platyrhynchos ) in the forested region of north-central Minnesota during the 1968-72 breeding seasons. Circumneutral bogs and seasonal wetlands were the most frequently used communities; the lakeshore communities most used were sand-gravel, overhanging brush, and bog mat. Based on the availability of habitat, the highest preference shown was for the seasonal community and the least for the softwood swamp; however, all communities were used to some extent during the breeding season. Lakeshore was always among the habitats most frequently used by pairs. Twelve nest were found, nine in nonpermanent wetlands and three in upland forest sites. Mean home range was 210 ha for hens and 240 ha for drakes. The long axis of the home ranges of drakes and hens averaged 2.8 and 2.7 km, respectively. Hens had smaller home ranges during the laying period ( x̄ = 70 ha) than during prenesting ( x̄ = 135 ha).

Minnesota↗
USGS1975

Utilization of Skylab (EREP) system for appraising changes in continental migratory bird habitat

The author has identified the following significant results. Surface water statistics using data obtained by supporting aircraft were generated. Signature extraction and refinement preliminary to wetland and associated upland vegetation recognition were accomplished, using a selected portion of the aircraft data. Final classification mapping and analysis of surface water trends will be accomplished.

Technical Report↗
USGS1974

Effects of radio packages on wild ducks

A total of 211 wild, free-flying mallards ( Anas platyrhynchos ) and wood ducks ( Aix sponsa ) were equipped with breast-mounted radio packages during the breeding seasons of 1968-72. Known predation loss was 7.6 and 12.0 percent for mallards and wood ducks respectively, 60 percent occurred within 3 weeks of instrumentation. The highest predation rate for mallards was 0.0048 kills per tracking day and 0.0136 for wood ducks. A higher direct recovery rate for instrumented birds (19.5 percent) than noninstrumented birds (8.1 percent) was probably due to the novelty of the transmitter to hunters. Departure patterns and locations of direct recoveries were similar between radio-equipped and normal-banded birds. Among female wood ducks with radios, recovery rates were lower than expected. Hunters indicated that 84 percent of the instrumented ducks recovered were in good or excellent condition. Recaptures of ducks as long as 1 year after being equipped with radio packages indicated that feather wear and skin abrasion were not serious. A high rate for feeding on land by instrumented mallards was probably due to our ability to more easily locate and observe these birds in cover. Preening rates were higher for instrumented ducks. As the birds became adjusted to the package, preening decreased and feeding on water increased. Social and breeding behavior of instrumented ducks did not appear to be adversely affected by the radio package.

Minnesota↗