FW 404: Conserving Bobwhite and Other Wildlife in Agricultural Landscapes, 11/18

Global Declines in Upland Gamebirds

• Gray partridge in Italy, Ireland, England

• Pheasant in Austria and central US

• Spotted tinamou in Argentina

• Global land use intensification

  • Overgrazing and shifts to non-native pasture grass

  • Conversion to intensive agriculture and forestry

• Fire suppression or reduced ignitions (exclusion)

Similar Changes in NC

• fewer larger farms (consolidated ownership)

• more efficient machinery

• advancements in herbicides and insecticides

• land conversion to urban

• few fallow fields; instead, double crops

• fire exclusion

• forests with high canopy cover %

Northern bobwhite population trends—NC

Early Concerns on Farmland

• mowing of ditch banks and field edges

• insecticide toxicity

• clean farming remains a concern

NO poisoning from insecticides

• broos use crop fields/borders when sprayed

• lannate and larvin insecticides

• sprayed over imprinted broods

• no effects

Farm units with field borders had:

• more birds

• more nests/bird

• smaller movements

Chick feeding efficiency

Landscape-scale Experiment

• four farms in each of hyde, tyrrell and wilson co, nc and amelia co, va

• farms were from 250-500 acres

• control, predator reduction (17 days), field border (10% of cropland), field border and predator reduction

• followed for 4 seasons

Build it and they will come

• trapping alone provided no benefits

• quail increased more than 50% after borders

• borders + trapping slightly better than borders

Removing predators was expensive and of questionable value

• recolonized rapidly

• same number of caps each year

Landowner Concerns About:

• lost crop production

• increased insect damage to crops

• social barriers (clean farm mentality)

• maintenance

Economics of Field Borders

• Field borders did not contribute to pest problems and may enhance beneficial insect populations

• Research contributed to introduction of field borders into the Conservation Reserve Program (CP-33)

Characteristics of CURE

• no more “shot-gun” approach

• focus management efforts in best landscapes

• 50-70% row crops, 20-40% woodland, <20% pasture

• 

Does the CURE concept work?

• high percentage of habitat may:

  • facilitate dispersal and year round survival

  • disperse predators and increase nest survival

Does habitat patch shape matter?

Landscape context (5000 ac)

Habitat patch shape summary

• Linear borders

  • ~3-m (10-feet) wide

  • Average length = 475 m (range = 66 to 1,940)

• Nonlinear blocks

  • Average size = 0.25 ha (range = 0.05 to 2.48)

• About 2-3% of row crop area on each farm

Non-linear Blocks Increased Quail

• 57% increase with nonlinear field borders

Quail Increased in CURE Landscapes

• 87% increase in agriculture-dominated landscapes

Summary Implications

• Borders increased quail by 45%

  • Nonlinear borders best

  • Agriculture-dominated landscapes best

• Increase less than in other studies

  • Rates of increase proportional to border size or % of cropland that is converted

• Increase immediate

  • Where do birds come from?

Why Does Landscape Matter?

• Does it affect occupancy dynamics?

  • Local occupancy (presence-absence)

  • Extinction in borders or habitat patches

  • Colonization of borders

• What are the relative effects vs local habitat improvements (e.g., create a CP-33 border) in different landscape conditions?

Influence of Variables on Density

• 2,322 male bobwhites detected over 6 years

• Densities 29% greater at sites with CP-33

• Densities decreased as:

  • Urban increased

  • Pasture increased

  • Forest increased

• Extinction increased as:

  • Urb and FOR increased

  • Cropland decreased

Landscape Matters

• Field borders increase density locally

• Borders don’t influence large-scale processes

• Colonization and extinction linked to landscape

• Cropland is “permeable” to dispersers

•     Prevents local extinction

  • Urban, pasture, and closed-canopy forest are not

Are Planted Borders Better?

• Fallow borders status quo

  • Proven benefits to quail

  • But few nectar-producing plants

  • Hence, few pollinators and adult parasitoids

• Planted native grasses + wildflowers

  • Conserve beneficial insects and attractive

  • Also provide quality brood cover for quail?

• native grasses/wildflowers, native wildflowers, fallow, mowed

Summary Implications

• planted borders comparable to fallow

• mowed borders have food but lack cover

• planted borders good choice when:

  • establishment $$ available (728$/acre)

  • beneficial insects are an objective

  • aesthetics are important

• fallow borders most efficient for bobwhite

Farm-level population study

• compared bobwhite populations between: 

  • farm with 9% in non crop early succession

  • farm with no habitat improvement

2-year study

• Captured and radiocollared 241 individuals

• 160 birds survived until breeding season

• Located 71 nests

  • 64 were on improved farm 

  • 7 on unimproved farms

• 31 nests hatched 335 young over the 2 years 

• 64% incubated by female, 36% by male

Nesting Cover Limiting Factor

• 47% nest success on improved farm

• 29% nest success on 2 unimproved farms

• Unimproved farm nesting ecology

  • Birds didn’t nest or nested in poor quality locations

  • Corn, hay field, closed canopy forest

  • Adult survival was relatively high

• Improved farm nesting ecology

  • 64% of nests located in ES areas (11% of farm)

  • Another 10% of nests adjacent to ES areas

  • Nest sites had greater perennial forb and grass cover

What Barriers Persist?

• “Neat and Green” mentality – social norms

• Too much mowing

• Limited money to support conservation

• No control of the “landscape”

• Poorly managed forests – closed canopy

• Lack of prescribed fire

• Misdirected blame – “it’s the damned hawks!”