TECHNICAL BULLETIN NO. 634 MARCH 1939 FOOD OF GAME DUCKS IN THE UNITED STATES AND CANADA By A. C. MARTIN and F. M. UHLER Associate Bloloftlsta Section of Food Habits DiTision of Wildlife Research Bureau of Biological Surrey UNITED STATES DEPARTMENT OF AGRICULTURE, WASHINGTON, D.C. For lale by the Superintendent of Documents, Wuhington, 1). C - Price 40 c PLATE 1 Tech. Bull. 6J4. U. S. Dcpt. of Agriculture B7330M PINTAIL DUCKS (DAFILA ACUTA TZITZIHOA) AT EDGE OF MARSH FEEDING IN BEDS OF AQUATIC VEGETATION. Mate on guard; female tipping for submerged food. TECHNICAL BULLETIN NO. 634 MARCH 1939 UNITED STATES DEPARTMENT OF AGRICULTURE WASHINGTON, D. C. FOOD OF GAME DUCKS IN THE UNITED STATES AND CANADA' Bj A. C. MARTIN and F. M. UHLEB, associate biologists, Section of Food Habits, Division of Wildlife Research, Bureau of Biological Survey CONTENTS Page Page Introduction _ .._ 2 PART. 2.-—Principal duck foods, etc.—Con. PART 1.—Regional data on duck foods 3 Plant foods—Continued. The regional-locality basis of food evalua- Ranunculaceae: Buttercups 83 tion 3 Hamamclidaceac: Sweetgum _. 86 Sources and selection of data 7 Vitaccae: Wild grapes 88 Summary of data for the United States Onagraceae; Waterprimroses 88 and Canada _ 8 llaloragidaceae; Watermilfoils, mer- FART 2.—Princi[)al duck foods: Their identifi- maidweed«, marestail 89 cation, value, and range 19 Umbelliferae: Pennyworts 92 Plant foods 19 Styracaceae: Snowbells 94 Algae 19 Convolvulaceae: Dodders -.. 94 Characeae: Muskgrasses 20 Boraginaceae: Heliotropes 94 Marsileaeeae: Pepperworts 22 Scrophulariaceae : Waterhyssops 95 Pinaceae: Baldcypress 22 Tontibulariaceae: Bladderworts 95 Sparganiaceae: Burreeds 23 Rubiaceae: Buttonbush_.. _. 96 Najadaceae: Pondweeds, wigeongrass, Compositae: Beggarticks, watermari- naiads, eelgrass 24 gold, goldflelds _. 96 Juncaginaceae: Arrow-grass 38 Animal foods... 97 Alismaceae: Arrowheads, delta duck- Mollusca: Snails, bivalves 97 potato - - - 39 Insecta: Insects 98 Butomaeeae: Flowering-rush 41 Crustacea: Crustaceans 99 Hydrocharitaceae: Wildcelery, frog- Pisces: Fishes 100 bit, waterweeds _ 42 PART 3.—Propagation of waterfowl food plants Gramineae: Wildrice, wild millets, and development of feeding grounds 103 cereals 44 Choosing propagativa material _ 103 Cyperaceae: Chufa, bulrushes, spike- Aquatic types 104 rushes, sedges 53 Marsh types _. 104 Araceae: Arrow-arum 67 Dry-soil types 104 Lemnaceae: Duckweeds 67 Harvesting and temporary field care 105 Commelinaceae: Dayflower 70 Storage and germination 107 Pontederiaooae: Pickerel weeds, water- Shipment .,. HO stargrass 70 Planting... Ill Marantaceae: Thalia 71 When to plant.. -. 112 Myricaceae: Waxmyrtlcs, bayberry... 71 How to plant .. 112 Betulaceae: Alders 71 Yields and food values _ 114 Fagaceae: Oaks 72 Factors that retard growth and suggested Urticaceae: Walter-elm 72 remedies .__ .- 116 Polygonaceae: Smartweeds, docks 73 Physical factors 116 Chenopodiaceae: Glassworts 79 Chemical factors - 124 Amaranthaceae: Waterhemps, pig- Biological factors - 129 weeds 80 Economic factors 140 Ceratophyllaceae: Coontail 82 Summary _,_ 142 Nymphaeaceae: Waterlilies, water- Literature rited 143 shield, spatterdocks _ - : _ S2 Index -- 149 1 .Submitted for publication May 17, 1938. 79025°—39 1 INTRODUCTION An a-wakened public interest in the restoration of -u-atfirfoTivl calls for dependable information on which to base programs for the im- provement of breeding and feeding grounds ^pl. 1) of the birds by the production of food and cover. To minimize waste of funds and loss of effort through the introduction of unsuitable propagativo material it is essential that the important plant and animal foods be known and that consideration be given to their normal distribu- tion and to environmental and other limiting factors. Over a period of many years the Bureau of Biological Survey has investigated the food habits of game ducks and has studied the propagation of the plants on which they feed. The results, dealing on the one hand with special groups of plants suitable for propaga- tion and on the other with the food habits of particular groups of waterfowl, have been published in several reports {39, J^l, Iß,^ 4'^, 44, 45, i<9, (J3, 87) ^ most of which are no longer available for distribution. In this bulletin the writers have attempted to consolidate the avail- able information on waterfowl foods, including much recently gath- ered in field investigations.^ The material is presented in three ma- jor divisions, with a view to rendering three distinct services in tlie field of waterfowl research and management : The first part presents a statistical index to the preferred duck foods in the various regions of the United States and Canada, based on analyses of nearly 8,000 stomachs or gullets of 18 species of game ducks. The second part is designed to facilitate recognition of some 200 of the principal food items by means of a series of outline descriptions, illustrations, and distribution maps. The third part contains practical sugges- tions on the propagation of waterfowl foods and the development of feeding grounds and discusses principles related to the embryonic Science of producing duck foods. - Italic numbers in parontliescf? rciev to Literature Cited, p. 143. 3 Grateful aclinowleàîiment Is made of the help of numerous cooperators, particularly W. C. Muenscher, of Ornell University, for data on seed germination ; R. T. Clausen, of Cornell University, for information on the taxonomy and ranse of the ffenus ]\'njnN ; M. n. Fernald, of Harvard University, for assistance from numerous published studios on plant distribution ; and J. B. Svvallen, of the Bureau of Plant Industry, U. S. Depart- ment of Agriculture, for advice on grasses ; and the following coworkers in the Section of Food Hahits, Bureau of Biological Survey : Neil Hotchkiss, for many botanical deter- minations and for obtaining much illustrative material : A. L. Nelson, for illustrative specimens : W. S. Bourn, for contributions on matters of physiology and proi>agation ; and Alma Rutledge, for aid in the elaboration of statistical data. Various regional and local floras, plant catalogs and list.s. monographs on certain groups, and three herbaria have been consulted in determining nomenclature and range. PART 1—REGIONAL DATA ON DUCK FOODS THE REGIONAL-LOCALITY BASIS OF FOOD EVALUATION In attempting to make either a continental or a Nation-wide evalu- ation oJE duck-±ood resources it is essential to begin witli regional subdivisions, in order to allow a correct appraisal of food plants that are of restricted distribution. Some of the most valuable of these have wide ranges, but many others are limited to circumscribed habitats. Thus wildrice and wildcelery and many other plants use- ful as duck foods, but less generally recognized as such, including sawgrass, jointed spikerush, alkali bulrush, waterhemp, and baldcy- press, have little or no importance to waterfowl outside definite regions. To give proper recognition to food elements of limited distribu- tion, that is, to avoid either underrating or overrating them, the pres- ent treatment has delimited eight major regions of food resources for game ducks, of which six are more or less natural units in the United States and two are arbitrarily made for Canada. These are mapped in figure 1. The regions are designated as follows: 1, At- FiGüRE 1.—Duck-food regions and the collecting localities listed In table 1. In the United States the six regions are within distinctive natural boundaries based upon essential homogeneity of their duck-food plants; in Canada the limits of the two regions are arbitrarUy made because of the meager data at hand ; in all cases large regions have been chosen to avoid objectionable complexity. 4 TECHNICAL BULLETIN 634, T'. S. DEPT. OF AGRICULTURE lantic coast; 2 eastern; 3, lower Mississippi; 4, Gulf coast; 5, western ; 6, Pacific coast ; 7, eastern Canadian ; 8, western Canadian. In addition to these eight major food provinces, it has seemed de- sirable to employ many (247) secondary units, or "localities," in the effort to prevent statistical distortions arising from disproportionate emphasis on local collections of duck stomachs. In the Biological Survey's extensive files of stomach-analysis cards it happens that some duck-concentration localities are represented by one or only a few records, whereas others, favored by special cooperation or by some local investigation, such as an inquiry into oyster damage by scaups, may have their stomach-material totals running into the hundreds. To lump together indiscriminately such inequable ac- cumulations would not yield a reliable index of regional food habits : the total would be excessively flavored by data from a few sources and might be much more representative of those few sources than of the region as a whole. Hence, the expedient has been employed of treating each locality as an entity, to be summarized individually and then to be combined with other summaries or with averages of numerous other localities within the region. Furthermore, rather than reduce all localities to single-weight level, it has been deemed advisable to grade or rank them in five categories, thereby giving graduated preference to places that are more adequately represented by stomach records and tending to level off extremes of inequality. The basis of evaluation is to rate localities having 20 or more stomach analyses at 100 percent; those with 10 to 19, at 80 percent; 5 to 9, at 60 percent ; 3 or 4, at 40 percent ; and those represented