FW 404: Managing Waterfowl Habitat, 11/13

Managing Waterfowl Habitat

Rule No. 1

• Without a sound knowledge of the natural history of the species you are managing for, your likelihood of providing the quality, quantity and suitable arrangement of habitat for a particular species is doubtful

Waterfowl Species

• Wintering waterfowl - 20+ species

  • most common = Tundra swan, Greater snow geese, green-winged teal, northern pintail, wood duck, lesser scaup, American wigeon, ring-necked duck, and ruddy duck

• Breeding waterfowl - 3+ species

  • most common - wood duck, non-migratory Canada geese, and mallards

    • also American black duck, gadwall, hooded merganser

NC Wintering and Breeding Waterfowl Numbers

• Dabblers 95,000-140,000

• Divers 75,000-80,000

• Snow Geese 14,000-53,000

• Tundra Swans ~70,000

• Atlantic Brant <1,000

• Breeding Wood Ducks ~350,000+

• Breeding/Resident Canada Geese ~150,000

• Breeding Hooded Mergansers ??

Waterfowl Life Cycle

• Wintering

  • migration to and from wintering grounds

  • pre alternate molt in males

  • pair bonding

  • re basic molt in females

• Reproduction

  • egg laying

  • incubation

  • brood rearing

  • then molt flight feathers

Species Distribution

• a variety of vegetation types are used

• waterfowl are mobile and exploit new food

• habitat “preferences” reflect niche and food segregation  (linked to psychological traits)

• Dabblers

  • select shallow water <10 inches

• Divers

  • select open water

  • select water up to 10 feet

• Geese/tundra swans

  • use dry agricultural fields and shallow wetlands

• sea ducks (scoters, long-tailed duck, eiders)

  • use deep water, typically offshore

Dabblers vs. Divers

• mallard

  • dabbler

  • tip into water, cannot really dive, shallow hunting

  • land majestically and jump up

• lesser scaup

  • diver

  • goes below the water

  • crash landing

Carnivores

• hooded merganser: diver for large invertebrates, small fish, amphibians

• northern shoveler: surface dabbler for zooplankton, snails, small aquatic insects, small seeds

Herbivores

• canada goose: grazer on sedges, grasses, aquaic plants

• american widgeon: dabbler for aquatic plants and seeds, grazer on sedges and grasses

• gadwall: dabbler for algae, aquatic plants, moist-soil plants

• northern pintail: subsurface dabbler for large moist-soil seeds, marsh inverts

• green winged teal: Dabbler for small moist-soil seeds, marsh inverts

• ring necked duck:  Diver for seeds of floating plants and aquatic plants

Omnivores

• mallad: subsurface dabbler for acorns, moist-soil seeds, detrital inverts

• wood duck: Surface feeder for acorns, small seeds, drupes, samaras, aquatic insects

Environmental Characteristics

• typically in NC, hot and dry summers and fall, increasing by mid fall, wet in winter and spring

• lowest elevation: rivers, open water (lakes and ponds, swamps)

• low elevation = Submerged aquatic vegetation, emergent wetland, dense shrubs (e.g. marshes, ponds, button bush/willow swamps)

• mid level elevation: flooded during winter & early spring (e.g. sloughs, bottomland hardwoods: overcup oak, maple, scattered cypress)

• higher elevation = flooded periodicallly during winter (red oaks, winged elm understory)

• highest elevation: uplands (e.g. hickory, plants intolerant of flooding)

• tree gaps = shade intolerant plants flourish (e.g. grasses, sedges, forbs, young trees, moist-soil plants)

Waterfowl Managers

• USFWS National Wildlife Refuge System

  • 10 NWRS, purpose migratory birds

• NCWRC

  • manage waterfowl impoundments

• Ducks Unlimited

  • DU has worked to conserve over 130,000 acres of waterfowl habitat throughout NC since 1985

• Natural Resources Conservation Service

  • farm bill programs

  • wetland reserve program

• Private Landowners

Habitat Management

Habitat Management Goals*

• to conserve broad, regional wetland complexes

• isolated, small wetlands receive little use

• to provide the resources needed by waterfowl for parts of their annual cycle

Basics

• water management is fundamental

• extensive alteration of hydrology has occurred

  • levees, channelization, and land leveling

  • must restore or modify the hydrological function

• cannot control large-scale hydrology, so must rely on smaller scale manipulations to provide habitat,

  • e.g. can’t control flow volumes of the Roanoke River

Wetland Manager’s Toolbox

• Levee/dike construction

• water control structures

• water pumping stations

• diversion of water sources

• restoration (e.g. wetland reserve program)

• all likely require permits (e.g. 404)

Moist-Soil Management

• construct levees/dike and water control structures that allow manipulation of water levels seasonally

• wet in winter and moist in summer

• encourages germination of desirable annual and perennial wetland plants that provide food

• water level manipulation reverses, retards, or advances plant succession

• plant response depends on:

  • seed bank

  • timing of annual draw downs

  • stage of succession (i.e. time since area was flooded continuously or disturbed by disking or burning)

• strive for 30-70% vegetation to water ratio

• ideal 50:50 ratio called “hemi-marsh”

Management Scenario:

• Year 1: Fall/Winter Flood >> Spring Gradually dewater >> Summer Saturate soils- Repeat 2 years

• Year 3: Fall/Winter >> Flood >> Early spring Dewater >> Summer Disk, burn, mow or herbicide treatment >> Late summer Saturate soils- Return to Year 1

Must disturb landscape or woody encroachment occurs.

THREE-YEAR CYCLE

General Plant Response

• EARLY (March) DRAWDOWN – most common

  • SMARTWEEDS

• MID-SEASON (April) DRAWDOWN

  • MILLETS

• LATE SEASON (May/June) DRAWDOWN

  • FALL PANICUM and other grasses

Disking/Plowing/Tillage

• Set back plant succession

• Scarify seeds & stimulates annuals 

• Seed-producing plants (e.g., millets)

Prescribed Burning

• Reduce cover of undesirable/invasive plants (e.g. Sesbania, cattail) for a short time – no kill 

• Recycle nutrients 

• Reduces aboveground plant biomass 

• Creates marsh heterogeneity 

• Stimulate seed bank 

• Promotes perennials

Herbicides and Mowing

• Herbicides to control undesirable plants (e.g., Phragmites, alligator weed, woody)

• Mowing reduces tall biomass

  • Promotes thatch 

  • Promotes grass and woody sprouts 

  • Possible loss of seed production and germination

Desirable Wetland Plants (Freshwater systems)

• smartweed (annuals best)

• wild millet

• panic grasses

• spikerushes

• bulrushes

Common Submerged Aquatic Species

• wild celerey

• eurasian milfoil

• muskgrass

• widgeon grass and bushy pondweed

• redhead grass

Undersirable Wetland Plants (freshwater systems)

• moist soil emergent wetlands: phragmites, alligator weed

• submerged aquatic vegetation: parrotfeather, giant salvinia

Greentree Reservoirs

• bottomland forest shallowly flooded in fall and winter

• mallards, black ducks, gadwall, wood ducks

Greentree Reservoir Strategy

• maintains flooded, mature hardwoods

• flooding makes available mast (acorns), benthic inverts, and understory plants

• red oaks best (willow and water)

• flooded during dormancy limits tree stress

• vary flooding regimes to prevent stress on trees

• delay flooding if regeneration is desired

• flooding should be shallow (<18”)

Agricultural Fields

• Winter flooding of harvested and non-harvested agricultural crops (corn, soybean and rice fields)

• Lower invertebrate abundance than moist soil impoundments

Wood Duck Nesting and Brood Cover

Brood Cover

• 75% vegetation and 25% open water

• dense emergent wetland plants (American lotus, cattail, pickerelweed)

• shrub thickets (buttonbush, willows)

• calm water

• strong, persistent overhead cover is present

• american lotus and buttonbush

Beaver Ponds

Take Home Lessons

• know species natural history

• know site

• have an objective

• monitor results and adjustment

• wetlands are dynamic

• shallow water is best

• think beyond one season