HARVEST MANAGEMENT

John W. Connelly1, James H. Gammonley2 and Thomas W. Keegan3

1Idaho Department of Fish and Game, 1345 Barton Road, Pocatello, ID 83221 2Colorado Division of Wildlife, 317 W. Prospect Road Fort Collins, CO 80526 3Idaho Department of Fish and Game, 99Highway 93 N, Salmon, ID 83467

INTRODUCTIONINTRODUCTION► Interest in managing harvests has been widespread throughout

history Elements can be dated to the eighth century when Charlemagne instituted a

detailed set of game laws

► Harvest management in North America dates to colonial times► Enactment of Federal Aid to Wildlife Restoration Act in 1937

provided states with a stable funding source to further support harvest management programs► For many biologists working for state and provincial wildlife agencies, harvest management

is where the “rubber meets the road”

► Our purpose is to discuss the rationale and biology underlying harvest management in NA and provide examples of successful programs We also provide a synopsis of literature and attempt to identify and discuss

principles

RATIONALE FOR HARVESTRATIONALE FOR HARVEST

►In North America, states and provinces are responsible for harvest regulations pertaining to “resident” wildlife, while federal authorities set regulations for migratory game birds

►A general underpinning of a harvest management is that a biological surplus exists, which can be harvested with little impact on subsequent breeding populations

Approaches to Harvest ManagementApproaches to Harvest Management

►The 3 approaches to harvest management include:

(1) harvesting at a low rate to ensure population increase

(2) harvesting to maintain a population

(3) harvesting to reduce a population

Basic Components of Harvest Basic Components of Harvest ManagementManagement

►Harvest management includes 3 basic components:

(1) inventory of populations

(2) identification of population and harvest goals

(3) development of regulations allowing goals to be met

Requirements for Successful Requirements for Successful ManagementManagement

►Four basic requirements for successful, informed management of harvests

1. Develop and agree upon explicit goals and objectives

2. Implement actions designed to achieve objectives

3. Have some idea of the likely effects of alternative management actions

4. Measure the outcome of actions in relation to management objectives

Principles—Past and PresentPrinciples—Past and Present►Additive Mortality

Each animal killed by hunters is an additional death that adds to natural mortality, resulting in total mortality being greater than if hunting did not occur

Mackie et al. (1998) reported that hunting was additive to overwinter mortality for white-tailed and mule deer; Bergerud (1988) suggested this applied to many grouse species

►Compensatory Mortality Occurs when animals have relatively stable annual mortality,

regardless of which decimating factors may be acting on the population

Recent work suggests upland game hunting mortality is often not compensatory

Additional Principles—Past and Additional Principles—Past and PresentPresent

►Diminishing Returns Indicates that, past a certain point, hunting is largely

unrewarded, resulting in relatively few hunters in the field, suggesting hunting is largely self-regulating

The idea of diminishing returns appears to have little value for present-day harvest management

►Doomed Surplus Number of animals produced that exceed the capacity of the

habitat to support and keep secure from predation A number of wildlife species actually have high overwinter

survival and this concept seems to have limited usefulness

Additional PrinciplesAdditional Principles►Harvestable Surplus

Indicates most animals produce more young than necessary to maintain the population; this excess can be removed by hunting without affecting the population.

McCullough (1979) challenged this concept by arguing that it fails to include “the dynamic and compensatory nature of population responses.”

►Inversity An inverse relationship has been proposed to exist between

productivity and abundance Roseberry (1979) concluded that the system’s ability to

compensate for hunting losses progressively deteriorates as harvest increases

More PrinciplesMore Principles►Opening Day Phenomenon

Suggests most mortality for a given species occurs on opening day of the season because that is when most hunters are afield

Appear to be few published data available documenting hunting pressure and harvest throughout the season

►Threshold of Security Population size above which some animals are not secure from

predation Romesburg (1981) indicated this concept passed into the wildlife

profession without being critically evaluated or tested

Sources of UncertaintySources of Uncertainty

►Sources of uncertainty about the relationship between hunting regulations and game populations

Partial Observability

Partial Management Control

Structural Uncertainty

Environmental Variation

Management of UplandManagement of UplandGame HarvestsGame Harvests

►Development of Harvest Strategies

Early Years (1900–1944)►Largely characterized by reduction in bag limits and season

length for many species of upland game

Changing Strategies (1945–1980)►Harvest strategies tended to stabilize and became somewhat

more liberal in the 1960s and 1970s►There was a strong tendency to believe reproductive

characteristics and effects of exploitation were the same for all species of upland game

Development of Harvest Strategies Development of Harvest Strategies for Upland Gamefor Upland Game

Current Knowledge (1981–2009): A New Paradigm

►New information suggesting earlier views of harvest management were not always correct

►During 1980s and 1990s, evidence began to suggest that, under some circumstances, harvesting may have an additive effect

►Recent information suggests hunting mortality should be viewed as occurring along a continuum and not as categorical (i.e., either compensatory or additive)

Inventory of Upland GameInventory of Upland Game

►Inventory

A general approach would base harvest on abundance of the species, but this is rarely done for upland game

►Instead, most harvest strategies seem to have been developed through trial and error

Harvest Surveys of Upland GameHarvest Surveys of Upland Game

►Harvest Surveys

Most states have reduced emphasis on population monitoring because of emphasized collection of harvest data

Many estimates of harvest have wide confidence intervals, making comparisons among areas or years difficult►Lack of population data makes it virtually impossible to

assess proportion of the population taken by hunters

Developing Regulations for Upland Developing Regulations for Upland GameGame

►Developing Regulations

Varies among wildlife agencies Initial steps include:

► Soliciting comments from agency personnel and public► Regions or other administrative units then formulate

recommendations for the chief administrator of the agency’s wildlife program

►Recommendations are discussed with the agency director►Recommendations are passed on to the Wildlife Commission

for approval

Population Responses of Upland Population Responses of Upland Game to HuntingGame to Hunting

►Population Responses to Hunting

Until the late 1970s, most studies suggested there were few adverse effects of exploitation on upland game

Within the last 25 years, numerous studies have documented adverse effects of hunting on upland game species

Kokko (2001) warned that ignoring information on species and population characteristics will “easily cause hunting to be harmful to an unnecessary extent.”

Future Directions in Upland Game Future Directions in Upland Game ManagementManagement

Stocking

►Seen as a legitimate and often necessary function of harvest management

►Stocking is likely reinforced among the hunting public because stocking is a common activity of fisheries management

►2 different harvest management programs involving game bird stocking

Release of birds before the gun Establish or augment existing game bird populations

Upland Game Shooting PreservesUpland Game Shooting Preserves

Shooting Preserves

►Hunting preserves offer additional hunting opportunity and a chance for individuals to train dogs prior to a general season

Appear to fill a need for more hunting areas at which hunters have a better than average chance at being successful

Development of Harvest Strategies for Development of Harvest Strategies for Migratory Game-birdsMigratory Game-birds

► Approaches have been shaped primarily by recognition these animals routinely cross local, state, provincial, and international borders

► Effective monitoring of populations and harvests, and development of regulations depends on cooperation across multiple levels of government

► Until reliable population and harvest surveys were developed, regulations in the United States were set subjectively

► As information was incorporated into the regulatory process, regional or flyway-specific differences were recognized, and regulations became more spatially complex

Models for Setting Regulations for Models for Setting Regulations for Migratory Game-birdsMigratory Game-birds

Models were developed for use in setting regulations, incorporating information from large-scale operational monitoring programs

Early models assumed hunting mortality was completely additive and density-independent

Anderson and Burnham (1976) produced new analyses indicating compensatory mortality and introduced the concept of structural uncertainty

Subsequent Model AnalysesSubsequent Model Analyses

Subsequent analyses provided mixed evidence on effects of hunting on annual survival in ducks, but hunting mortality appears to be primarily additive for geese

Recognition of alternative hypotheses about effects of hunting on population dynamics led to a greater focus on addressing partial management control and structural uncertainty

After a period of stabilized regulations, federal authorities in the United States adopted risk aversive conservatism risk aversive conservatism toward setting hunting regulations►Relatively restrictive regulations would be adopted for

populations at low levels

Inventory of Migratory Game-birdsInventory of Migratory Game-birds Federal mandates to consider status of migratory game birds when setting regulations motivated development

of extensive monitoring programs in North America

Monitoring programs support annual regulatory process and consist of annual collection of data on abundance, production, distribution, harvest, other population parameters, and habitat

Population monitoring programs for waterfowl have a longer history and are more extensive than surveys developed for most other migratory game birds

Since 1955, the U.S. Fish and Wildlife Service and the Canadian Wildlife Service have conducted annual aerial transect surveys, coupled with ground counts during May

Winter (Jan) surveys of waterfowl have been conducted since the 1930s

This survey is still the primary population index for ducks that occur outside of the May survey area, and provides population indices for many goose populations in North America

During May and July aerial waterfowl surveys observers record the number of ponds containing water along transects in southern Canada and the north-central US ► The Canadian Wildlife Service monitors wetland habitat conditions on a sample of survey transects each

year in southern Canada

Annual Harvest Estimates for Annual Harvest Estimates for Migratory Game-birdsMigratory Game-birds

Annual harvest estimates are obtained using surveys consisting of 2 components

►Hunter Questionnaire Survey: is used to obtain information on hunter activity and number of ducks and geese harvested each year

►Parts Collection Survey: involves mailing envelopes to a sample of hunters who are asked to mail in wings of ducks and tail feathers of geese they shoot

Harvest Information Program for Harvest Information Program for Migratory Game-birdsMigratory Game-birds

In 1991, a new Harvest Information Program was initiated to provide a reliable, nationwide sampling frame of all migratory bird hunters

Under HIP, each state collects the name, address, and birth date of each person hunting migratory game birds, asks each hunter a series of questions about their hunting success the previous year and provides this information to the USFWS

►The traditional sampling procedure was replaced with the HIP sampling frame beginning with the 2002–2003 hunting season

Role of Banding for Migratory Game-Role of Banding for Migratory Game-bird Managementbird Management

Mark–recovery methods enable managers to obtain important information about populations. To use these methods, individually numbered leg bands are placed on migratory game birds

Information helps identify distribution of harvest and harvest areas, estimate harvest rates and relative vulnerabilities to harvest of gender and age cohorts, and estimate age- and gender-specific survival rates

Governmental Roles in Regulating Hunting Governmental Roles in Regulating Hunting of Migratory Game-birdsof Migratory Game-birds

►Primary federal authority and responsibility for migratory birds was established after the signing of the Convention for the Protection of Migratory Birds by representatives from the United States and Great Britain in 1916

►Migratory Bird Treaty Act of 1918 implemented the convention in the US This Act was later amended to incorporate similar treaties with Mexico, Japan, and Russia Under the Migratory Bird Treaty Act, the Secretary of the Interior authorizes hunting and adops

regulations for this purpose

►Regulations must be based on status and distribution of migratory game birds and updated annually

►This responsibility has been delegated to the U.S. Fish and Wildlife Service

Flyway CouncilsFlyway Councils

In 1947 the United States was divided into 4 administrative Flyway Councils for establishing annual hunting regulations

Through these Councils, representatives from state and federal agencies in the United States, Canada, and Mexico have coordinate management activities and develop annual hunting regulations

The Regulations ProcessThe Regulations ProcessRegulations processRegulations process MonthMonth MonitoringMonitoring

U.S. Fish and Wildlife Service regulations Committee (SRC) meets to identify issues Flyway Councils develop recommendations

JanuaryFebruaryMarch

•Midwinter waterfowl and crane surveys•Parts Collection Survey wing bees•Hunter Questionnaire Surveys; banding analysis for duck harvest and survival rates

April–May Breeding waterfowl and habitat, dove call-count, and woodcock singing-ground surveys

SRC meets to recommend “early” season regulations Harvest survey results available

June Harvest survey results available

Flyway Councils develop recommendations July Waterfowl production surveys

SRC recommend “late” season regulations August Preseason duck banding

“Early hunting” seasons begin September Autumn surveys for sandhill cranes, greater white-fronted geese

“Late” hunting seasons begin October

Management of Migratory Game-bird Management of Migratory Game-bird HarvestsHarvests

► Features of adaptive harvest management for mallard populations Set of alternative models Measure of reliability for each model Limited set of regulatory alternatives Objective function or mathematical description of the objective(s)

► The setting of annual hunting regulations involves a 4-step process: Each year the optimal regulatory alternative is identified Once the regulatory decision is made, model-specific predictions for

subsequent breeding population size are calculated When monitoring data are available, model weights are updated New model weights used to start a new iteration of the process

Harvest Management of Overabundant Harvest Management of Overabundant SpeciesSpecies

Primary goal for migratory game birds continues to be prevention of overharvests

However, hunting has often been used to reduce or control the density of birds on local scales

Several continental populations of geese have grown rapidly►In 1999, U.S. Fish and Wildlife Service authorized new

methods of take for light geese and established a conservation order permitting take outside dates established by Migratory Bird Treaty Act

Management of Big Game HarvestsManagement of Big Game Harvests

►In contrast to harvest management of upland game and waterfowl, management of big game harvest is often more complex and contentious because:

Ability of hunters to differentiate among gender and age classes

Variety of weapons used for harvest

MANAGEMENT OF BIG GAME MANAGEMENT OF BIG GAME PopulationsPopulations

►Management of large mammal populations is a 4-step, linear process

(1) inventory (identify current or potential population status)

(2) define goals and objectives (identify desired population status)

(3) develop strategies to achieve objectives, (4) evaluate how well strategies met objectives

Inventory of Big GameInventory of Big Game Typically involves estimating current

population status

Biological capacity to produce and sustain a given species►Should be based on geographical areas containing

relatively discrete populations

Inventories may be designed to estimate population abundance or provide an index to population status ►Determine age and gender ratios

Harvest Surveys for Big GameHarvest Surveys for Big Game

►Harvest Surveys Surveys conducted by wildlife agencies estimate

harvest across multiple species, seasons, weapon types, and management units►Data collected include number of animals harvested by

gender and age class, hunter effort, location, date of harvest, weapon used

►Variety of methods to estimate harvest:►Check stations, mandatory checks, report cards, random

mail or telephone surveys, toll-free telephone service, Internet- based reporting

Harvest Strategies for Big GameHarvest Strategies for Big Game

►Development of Harvest Strategies

Harvest theory for most big game species is generally based on concepts of biological carrying capacity (K) and density-dependent population growth►Determination of K for wild populations is very difficult;

K often changes through time

Practical management of big game populations is more likely to be based on social carrying capacity

Developing Regulations for Big Developing Regulations for Big GameGame

Wide variety of harvest regulations and season structures are applied across jurisdictions and species ►Local tradition and history often play important roles in determining harvest

systems

Regulations should be easily understood by hunters and enforceable ►Concept of fair chase is integral to developing regulations, but definition of fair

chase varies

To provide a framework for evaluation, managers should implement regulations that are consistent and stable over long enough periods to encompass normal variability►Changing season length and timing annually will virtually eliminate the

possibility of estimating effects of different season structures

Evaluation is an often neglected aspect of the regulation process

Population Responses of White- Population Responses of White- tailed Deer to Huntingtailed Deer to Hunting

►Challenge for managers is finding ways to increase harvest, particularly for females

►Principles of sustained yield management based on density dependence can be applied with more certainty than in more variable systems

Population Responses of Mule Deer Population Responses of Mule Deer to Huntingto Hunting

►Minimum APRs are generally effective at reducing buck mortality and increasing total buck:doe ratios, but have almost invariably failed to increase mature buck:doe ratios or absolute number of mature bucks

►Effects of altering season length are equivocal and typically confounded by concurrent change in season timing

In general, reducing the number of days available to hunt has a negligible effect on total harvest

►Altering harvest management to increase buck ratios for the explicit purpose of increasing productivity is unwarranted

►Effects of female harvest depend on adult female natural mortality rates and fawn recruitment

Determine appropriate harvest rates based on population-specific demographic data and population monitoring

Population Responses of Elk to Population Responses of Elk to HuntingHunting

►Several regulatory approaches have proven successful in increasing bull:cow ratios

►Moving centerfire-weapon seasons out of rut typically reduces bull harvest rates

►Maximum APRs (i.e., spike-only) may increase bull ratios

►A somewhat complex season system designed to attract hunters to seasons where they would be less successful may increase bull ratios

Population Responses of Bear to Population Responses of Bear to HuntingHunting

As harvest rates increase, average age of males declines and proportion of females in harvest increases

►If females comprise ≤35% of harvest and average age of males is ≥4, population is likely stable►Refuge areas may serve as repopulation sources

for more heavily hunted areas

Sustained Yield ManagementSustained Yield Management

Maximum sustained yield (MSY) is achieved when populations are at approximately K/2

Management for MSY has received criticism and been blamed for overharvest of some species

In systems characterized by large variability in weather and habitat, density-dependent population responses may be overshadowed by stochastic processes, thus reducing appropriate yield levels

Principles of Sustained Yield Principles of Sustained Yield ManagementManagement

► Any exploitation of a population reduces its abundance

► Below a certain exploitation level, populations may be resilient and increase survival and/or production and growth rates to compensate for individuals removed

► When populations are regulated through density dependent processes, exploitation rates will tend to increase productivity and reduce natural mortality of remaining individuals

► Exploitation rates above maximum sustained yield will reach a point at which extinction will occur if exploitation is continued

► Age composition and number of animals remaining after exploitation are key factors in the dynamics of exploited populations

► If a population is stable, it must be reduced below that density to generate a harvestable surplus

► For each density to which a population is reduced, there is an appropriate sustained yield

► For each sustained yield, there are 2 density levels at which it can be harvested

► Maximum sustained yield may be harvested at only one density, about 1-half resource based carrying capacity

SUMMARYSUMMARY►As interest of nonhunters in management increases,

importance of biologically defensible harvests also will increase

►Changing landscapes will alter at least some wildlife populations Approaches to harvest management for some populations

will likely have to change►Management decisions backed by sound science and rigorous

data collection will alleviate some difficulties