• l ... I .....1 r v DEVELOPMENT OF MANAGEMENT STRATEGIES FOR MALLARD AND CANVASBACK Region 6 Materials used in support of presentation by Robert L. Croft at Project Leader's Meeting January 18, 1983 . -- • TABLE OF CONTENTS Page Introduction 1 Di stri buti on 1 Statement of Reponsibilities 1 Supply and Demand Mallard 4 Canvasback 5 Objectives Mallard 5 Canvasback 5 Definition of Problems Mallard 6 Canvasback 6 Analysis of Causes and Consequences Mallard 6 Canvasback 10 Description of Strategy Elements Habitat Development 12 Habitat Development off Service Lands 15 Management of Predation 17 Increase High Protein Foods (Service Refuges Only) 20 Habitat Preservation 20 Population Surveys 23 Research and Development 24 Disease Management 25 FWS Administration 26 Preliminary Screening 27 Characteristics of Affected Publics 28 Sources of Information 28 DEVELOPMENT OF MANAGEMENT STRATEGIES FOR MALLARD AND CANVASBACK INTRODUCTION This paper summarizes accomplishments from Regional Resource Planning efforts concerning the mallard (Anas platyrhynchos platyrhynchos) and the canvasback (Aythya valisineria) due~ The purpose is to provide a bases for developing four or five strategies to test, using the Mallard Management Model, for accomplishing the population objectives for mallards and canvasbacks in Region 6. To develop these strategies, a list and description of potential strategy elements is given. Our intent is to identify all potential strategy elements regardless of their cost or practicability for use in developing the test strategies. We need your help to review and to add potential strategy elements (management techniques) to this list. There are approximately 25 times more breeding mallards than canvasbacks in Region 6. It is our judgement that public demand requires the mallard to be the lead species for strategy development. Canvasback breeding habitat requirements are more precise than for the mallard. Therefore, canvasback strategies will be incre al add .tions to those strategies identified best for mallards. ",;)~ ~ ~ -t-- ~ ~ -8-, c-. ~ The Service's responsibilities, objectives, problems and rationale for the above actions are also present. DISTRIBUTION: The approximate distribution of breeding mallards and canvasbacks is given in Table 1. Figure 1 should be the location of Strata in Montana, North Dakota and South Dakota. The density by strata are based on a 10-year average breeding population for mallards and canvasbacks in the three States. The Regional objective is calculated by multiplying that porti on of the surveyed area (18.5 percent) within Region 6 in the Waterfowl Breeding Survey by the National objective (8,000,000 and 625,000 breeding mallards and canvasbacks, respectively). STATEMENT OF RESPONSIBILITY: The U.S. Fish and Wildlife Service is responsible, under the Migratory Bird Treaty Act, for the preservation, distribution, reintroduction, and restoration of game birds and other wild birds. The Animal Damage Control Act of 1931 authorizes the Service to resolve conflicts, usual ly crop depredation, between man and wildlife. Table 1. Distribution of 10-year Average of Breeding Populations of Mallards and Canvasbacks in Region 6 Compared to Land Area and Objective by State and Strata. Mallards (thousands) Canvasbacks (thousands) Square 197 2-81 197 2-81 State Stratum Miles Average Objective Average Objective Colorado 103,948 30 34.7 Kansas Tr Montana 353.9 419 .o 7.7 16.0 41 32,902 201.3 238.3 5.7 11.8 42 40,755 152.6 180. 7 2.0 4.2 Nebraska 76,612 42.0 48.5 North Dakota 512.8 608.0 33.2 69.0 43 19,835 122.1 144.8 3.0 6.2 45 26,625 277. 7 329 .2 23.3 48.5 46 14,238 96.0 113.8 6.9 14.3 47 7,821 17. 0 20. 2 0.0 South Dakota 382.5 453.0 9.3 19.0 44 27,299 144.0 170. 5 1.9 3.9 48 24,587 167 .4 198. 3 5.8 11.8 49 15,830 71.1 84. 2 1.6 3.3 Wyoming 97,914 67. 0 77 .4 Utah Tr 1 1 No figures to establish objective 2 ' b w i '". l, \ \ 'I ··- r,-..l / t - _( ) ( f I I I .) I I I f" i <Ju n• I. -- TRANSECTS AND STRATA FOR PRINCIPAL AREAS OF WATERFOWL BREEDING POPULATION AND PRODUCTION SURVEYS The Service, through the Administration of National Wildlife Refuge System Act, the Small Wetland Acquisition Act, and the Fish and Wildlife Coordination Act of 1958 is authorized to protect and manage waterfowl habitats and to provide for the use of the renewable resources in cooperation with other Federal, State, and private agencies or individuals. Historically, the Fish and Wildlife Service and State wildlife agencies have shared certain responsibilities. The Service has protected and managed waterfowl habitat and has established basic frameworks for hunting seasons, including season lengths, daily bag limits, and other restrictions based on the availability of migratory game birds. State wildlife agencies have been concerned more with meeting public demand to utilize ducks--hunting or other uses. Thus, the Service is primarily concerned with supply and the States are primarily concerned with demand for ducks. Species management is coordinated through the four Flyway Councils. SUPPLY/DEMAND ANALYSIS: Mallard The overall trend of mallards, as measured by the Waterfowl Breeding Bird Survey, has been downward from 12 million birds in the 1950 1 s to 8 or fewer million birds today. While the population has fluctuated since the 1950 1 s, each peak was progressively lower than the previous peak, followed by a steady decline in the 1970's. The demand for mallard hunting has remained high throughout the 70's. To maintain a harvest of about 5 million mallards without jeopardizing the breeding population will require a continental fall flight between 20 to 25 million mallards. The estimated harvest of mallards should be between 20 to 25 percent of the fall flight or approximately SO percent of the annual mortality. The Canadian Wildlife Service estimated the combined Canadian and U.S. harvest of mallards has exceeded 40 percent of the population in the surveyed area between 1975 and 1981. This harvest may have exceeded safe limits. Demand exceeds supply. The distribution of nonconsumptive demand and available mallards are virtually the same. It is assumed that all nonconsumptive demand is being met. Biological needs for a stable population of mallards may be a factor for serious consideration. Assuming that hunter caused mortality is compensatory, current data show that the mallard production in portions of the breeding range is not sufficient to maintain a stable population. 4 Canvasback The demand for hunting exceeds the available supply of canvasbacks. The canvasback has high symbolic value among waterfowl enthusiasts for its sporting tradition and aesthetic qualities. In many regions of the U.S. and Canada, hunting opportunities are limited by regulations currently in use to reduce the harvest of canvasbacks. Hunters want to increase canvasback numbers and reduce harvest restrictions (open closed areas and reduce point value). This bird is important to photographers, wildlife artists and bird watchers. The distribution of consumptive and nonconsumptive demands and the availability of canvasbacks are virtually the same. It is assumed that if the consumptive demand is met, the nonconsumptive demand will be exceeded. In Region 6, it is estimated that the breeding population of canvasbacks is about one half as large as it should be. This estimate is based on availability of breeding habitats within Region 6 compared to habitats in other portions of the canvasback breeding range. Biological needs may become an important consideration for this species because breeding habitat has been virtually eliminated in a large portion of its original breeding range in Region 6. Canvasbacks need specific combinations of wetlands, from seasonal to permanent ponds of various sizes and water quality to successfully hatch and fledge ducklings. Dra i nage of prairie potholes continues and inappropriate tillage of steep slopes in the Missouri Coteau is causing severe erosion. Resulting siltation is also destroying breeding habitat. OBJECTIVES: Mallard In Region 6, the objective is to increase the mallard breeding population, by 1990, within Waterfowl Breeding Bird Survey Strata 41-49 from 1.25 to 1.48 million breeding birds with the following distribution: Montana, 419,000; North Dakota, 608,000; and South Dakota, 453,000. Canvasback Increase the canvasback breeding population within the Waterfowl Breeding Bird Survey, Strata 41-49 from 50,000 to 104,000 breeding birds with the following distribution: Montana, 16,000; North Dakota, 69,000; and South Dakota, 19,000. Maintain an average age ratio of 1.3 immature females per adult female in the 5 fall flight. DEFINITION OF PROBLEM: Mallard The problem confronting the mallard in Region 6 is that the population is estimated to be approximately 230,000 breeding birds below the desired objective. This is a result of the basic fact that annual mortality exceeds the annual recruitment. Canvasback The basic problem confronting Region 6 i s that the canvasback breeding population is estimated to be 54,000 birds below the desired objective. The problem exists because the estimated annual recruitment rate of canvasbacks i s equal to or slightly less than the current estimated annual mortality rate. ANALYSIS OF CAUSES AND CONSEQUENCES: Mallard Since the turn of the century, breeding habitats of mallards have been encroached upon by man's agricultural practices which have gradually drained and cultivated the sloughs around which mallards nest. Draining sloughs and plowing new prairie lands continues today. The primary factor that has led to the decline of mallard population is low productivity. Low productivity is caused by three main factors: high annual hen mortality, low nesting success, and high ann immature mortality. Nearly all of these factors are ,n e with deficiencies in the mallards habitat.