Frank C. Bellrose

Relative Value of Natural Cavities and Nesting Houses for Wood Ducks

Low occupancy of nest houses by wood ducks (Aix sponsa) does not necessarily indicate an abundance of nest sites in natural cavities, but rather either a low breeding population or nest houses improperly constructed or placed. A low breeding population may be caused by high nest losses to predators, shortcomings in the breeding habitat, or shooting losses. Nest houses which afford superior protection from predators increase numbers of wood ducks, even in habitats with abundant natural cavities. On Quiver Creek in central Illinois, utilization of predator-proof nest houses increased the breeding population of wood ducks from 10-15 pairs to over 90 pairs. Cylindrical metal houses afford greater protection than board houses, but are widely acceptable only when (1) there is a high density of breeding wood ducks, (2) the breeding population is expanding, or (3) a local population is conditioned to nesting in houses. After initial use of metal houses by wood ducks, high nesting success is usually followed by increased usage as homing adults and yearlings swell the local breeding population. Adult wood duck hens usually return to the nesting areas where they last bred successfully. A large proportion of yearling hens return to their former rearing areas. Yearling hens nest later than older hens, and, by observing specific nesting areas and sites used by adults, are influenced to nest nearby and in similar accommodations. The homing of females to a specific nesting area emphasizes the advantage of grouping nest houses in units. Houses should be spaced according to habitat and potential breeding population: two to three per acre in high-quality habitat are recommended. The low rate at which nest houses have been used by wood ducks has disappointed waterfowl biologists in some states. They concluded that enough natural cavities already existed for nesting purposes and that production of young was not increased substantially by providing additional nesting sites. A difference in the rate at which houses were used by wood ducks is also apparent in Illinois, where nesting in houses has been studied continuously since 1938 (Hawkins and Bellrose 1940, Brown and Bellrose 1943, and Bellrose 1955). Through the years, various types of houses have been developed in an effort to reduce nest loss caused by predators (Bellrose 1955). Metal houses grouped in units showed a divergence in use between units that was difficult to evaluate. In 1958, a project was initiated to investigate the relative value of natural cavities and nest houses on a study area in Mason County, Illinois. Nesting of wood ducks in natural cavities was studied in this region from 1938 to 1941, but, for the next 17 years, studies were concerned only with nesting in houses. The principal objectives of this study were to (1) compare the degree of use accorded natural cavities and nesting houses by wood ducks; (2) compare nesting success in natural cavities with that in nesting houses; (3) observe the effect of an increased raccoon (Procyon lotor) population upon nesting success of wood ducks; (4) evaluate the selection of particular natural cavities by nesting wood ducks to improve the dimensions, design, and placement of nest houses; and (5) ascertain whether bands of Tanglefoot or metal strips placed around tree trunks would prevent raccoons from reaching nesting cavities. The original study area extended 15 miles north and 20 miles south of Havana, Mason 1 Present addresses of Kenneth L. Johnson and T. Udell Meyers: Nebraska Game, Fish and Forestation Commission, Lincoln; and U. S. Marine Corps, San Diego, California, respectively.

The Relationship of Muskrat Populations to Various Marsh and Aquatic Plants

The primary objectives of this study were to determine plant food preferences of the muskrat (Ondatra zibethica), in winter and the relative muskrat populations supported by various marsh plants in Illinois. Secondary objectives were to evaluate the influence of depth of water and fluctuating water levels on density of dwelling houses and the relationship between dwelling and feeding houses. These investigations were conducted on the bottomland lakes of the Illinois River valley in the fall-winter seasons of 1940-41 and 1943-44, and on the glacial lakes of Lake County in northeastern Illinois in the 1943-44 season.

THE VALUE OF WATERFOWL REFUGES IN ILLINOIS

found immediately behind the headgate in the two canals having one period of decreased flow before headgate closure. Of the marked recoveries, 73 per cent in one canal and 100 per cent in the other were recaptured upstream from point of release for distances varying from 150 to 7500 feet. 7. The smallest marked fish (a 4.3inch eastern brook trout) which moved upstream traveled 1750 feet. A 12.9-inch rainbow trout traveled a maximum distance of 7500 feet.

THE ILLINOIS RIVER: A LESSON TO BE LEARNED

The ecological integrity of the illinois River, historically one of the most productive riverine ecosystems in North America, is being degraded by accelerated amounts of sediment resulting primarily from intensive agricultural land-use practices. The current biological value of the river system could disappear in less than 100 years.

A COMPARISON OF RECOVERIES FROM REWARD AND STANDARD BANDS

The importance of determining the proportion of the waterfowl population taken by hunters each year is widely recognized. Yet, population and kill figures for the entire continent have been so crude that they have provided only a rough index of the harvest. Kill figures collected from hunter reports, for example, have been found to be greatly exaggerated (Bellrose, 1947). Hunter kill figures from such sources are largely of value in indicating year-toyear trends in the take. At present, waterfowl banding records appear to offer a more valid approach to hunting losses than do comparisons of population and kill figures. The principal weakness of banding as a technique for evaluating kill is the failure of many hunters to report bands. An attempt was made to appraise this shortcoming by sending card questionnaires to Illinois duck hunters in 1944 (Bellrose, 1945). However, data are now at hand which appear to provide for a more accurate determination of the proportion of bands which are unreported by hunters. As a means of obtaining information on this problem the U. S. Fish and Wildlife Service in 1948 issued a

Fish and Wildlife Habitat Changes Resulting from Construction of a Nine-Foot Channel on Pools 24, 25, and 26 of the Mississippi River and the Lower Illinois River,

Abstract : The purpose of this report is to compare the fish and wildlife habitat in Pools 24 and 25 of the Mississippi River and Pool 26 of the Mississippi and Lower Illinois Rivers from before to after construction of the navigation dams. (Author)

Use of Nesting Boxes for Wood Ducks by Other Wildlife

A preliminary study of wood ducks (Aix sponsa) in the Illinois River Valley (Hawkins & Bellrose, 1940) indicated a shortage of nesting sites for this species. Subsequently, some 800 board nest boxes (P1. 15, A) were constructed by the Illinois Natural History Survey and placed along the Illinois and Mississippi rivers. It soon became apparent that species besides wood ducks, found the boxes to afford suitable den and nest sites. At times there was competition among species for possession of boxes. The presence of several species of birds and mammals in boxes yielded information on their food habits, reproduction, and ecology. Thus, it was deemed advantageous to study the use by other species.