Pop Dynamics Exam 3

1. Define and distinguish between the annual crop and inversity principles. What effect does harvest have on equilibrium density for each of the theories?

Annual Crop = Numbers produced in excess of winter threshold are surplus. May be harvested without affecting the long?term density. Harvest mortality simply replaces natural mortality, and does not affect equilibrium (winter) density. Pertains only to seasonal harvest.

Inversity = • Inputs & outputs balance at certain population density (i.e., K) • Harvest will reduce density. Pertains to harvest all year.

2. Describe and distinguish between compensatory and additive mortality. What role do thresholds play in distinguishing between compensatory and additive mortality?

Compensatory ? occurs when survival, reproduction or movement into the population increases because of the harvest of animals, thereby reducing the effects of harvest mortality on population growth.

Additive – occurs when harvest mortality adds to that of natural mortality


Hunting may be compensatory up to a certain threshold. Once exceeded, more hunting becomes additive. Challenge is to determine that threshold before setting harvest goals.

3. What species characteristics tend to be correlated with a greater ability to compensate for harvest mortality? What characteristics are correlated with low capacity to compensate?

 • Compensation greatest for species with higher background mortality – Short lifetimes & high reproduction • Compensation least for species with longer lifetimes & low reproduction

4. Describe how harvest mortality (coyote control) is compensated for in populations of western coyotes.

– Larger litter sizes – Increased reproduction in yearlings – Increased juvenile survival – Increased immigration

5. Describe the spatial harvest control method. Why is this method relatively ineffective in areas of fragmented habitat?

• Some areas closed to harvest to ensure abundant harvests in other areas: “refuges” • Adjusted movement rates among populations with and without harvest

6. How is net reproductive value a useful concept in understanding the difference between the effects of harvest mortality and natural mortality on animal populations?

Less effect when harvesting animals are of low reproductive value – Hunters take cow elk with high reproductive value vs – Wolves take older cow elk & calves, both of lower reproductive value

7. Explain how harvest mortality can result in genetic and resulting physical changes in animal populations.

Bighorn sheep trophy hunting in Alberta – For 30 years, any ram with a min legal horn size could be taken – Thus, hunters took rams that quickly grew big horns & body size, selecting  4?8 years old – Thus, removing them from population before they could breed • Implemented “full?curl” restriction – must extend beyond ram’s nose    

8. In the “Tale of Two Does” side bar of John McDonald’s article on “Deer Management in Massachusetts” how do environmental conditions affect each of the two does in the story and what are the implications of these effects for the demographic characteristics of deer populations in those two areas of the state?

Dover does are lower elevation than Savoy does so warmer climate, less snow, more abundant food, better food (gardening). Healthier does after winter are more likely to have twins or triplets so more deer in Dover than Savoy more people getting pissed.

9. What are the deer management goals for MA?

Healthy, Balanced Deer Population }

 Below Level where Major Impacts to Habitat/other Species are Seen }

Balance Social Desires and Tolerance ? Hunting/Viewing Opportunities ? Public Safety and Public Health ? Ag/Residential Property Damage

12. What data are collected at a deer check station and how do deer managers use these data?

• Sex

• Age (fawns, yearlings, adult/age classes)

• Dressed body weight

• Antler beam diameter

• Others ? # corpora lutea scars, liver condition, adrenal weight, tick abundance,


• Est. total harvest • Est. total effort expended • Sex ratio of harvest • Sex?specific age structure of harvest

13. Why does The Nature Conservancy consider too many deer to be perhaps a bigger threat to Eastern forests than climate change?

More immediate, happens faster, eat everything, drive out other species. Risks to people collision, lyme.

14. Identify the most serious challenges to maintaining deer density goals in Massachusetts.

Many interested parties with different goals. Success of hunter dependent.

14. Identify the most serious challenges to maintaining deer density goals in Massachusetts.

Many interested parties with different goals. Success of hunter dependent. No other predators

15. Be prepared to discuss the pros and cons of the 8 options for controlling deer populations as presented in the publication “An Evaluation of Deer Management Options” by Ellingwood and Caturano.

1. Hunting,

2. No management, starvation, (no predators)

3. Trap and Transfer, (expensive, where?),

4. Fences/Repellents (effort high, repellent only in no rain, expensive),

5. Birth Control (cost, non targets, logistics),

6. Feed them (pop still grows),

7. Sharpshooters (cost, no $ from hunters),

8. Predators (variable, too many people).

17. Describe the special problems associated with furbearer management.

Traps controversial , varying effectiveness (by-catch), and demand not constant (tied to market for pelts).

18. Describe the four types of traps used for trapping furbearers.

Foot holds (non-lethal, cruel?, most common),

Conibear (lethal, second common) ,

snares (lethal, 3rd common),

others (cage based, time senisitive but non lethal, least common).

19. Describe the characteristics that are used to evaluate traps?

Effectiveness – trap’s ability to adequately hold or kill a captured animal – usually measured as number of captures/100 trap nights – unpadded (73%) vs. padded (50%) foot?hold traps for coyotes – greatly affected by trapper experience.


Selectivity – extent that traps capture “wanted” vs. ‘Unwanted” species Factors affecting unwanted capture rates • trap type & trap site • type of set & bait used • time of year & trapper technique Highly variable ranging from no unwanted animals to 2 unwanted animals per wanted furbearer caught

20. How can injury from traps be reduced?

Efforts to reduce injuries – use of smaller traps – daily, early morning checks of traps – tranquilizer tabs – padded traps.

21. What is pelt sealing and why is it useful?

Mandatory tagging of pelts by state – Provides more accurate harvest information – Reduces bias in reporting process – Very costly logistically, so few states do it

22. Does this graph of furbearer harvest tell you about the status of the two furbearer populations?

Not Much! • Trapper effort • Pelt prices • Number of trappers

23. Why is it so important to have data on trapping effort to go along with data on the number of animals harvested each year?

Because effort is variable due to market changes. So If effort high but catch low means different than effort low catch low.

24. Other than population abundance what demographic characteristics of black bears are monitored in Massachusetts? What demographic characteristic of black bear populations has the most impact on population growth?

?Adult survival rates • Adult female survival rates have most impact on population

?Age at first reproduction

?Average litter size • 1st litters vs subsequent

?Cub survival • 1st litters vs subsequent litters

25. Other than population abundance what other aspects are considered when deciding how to manage bear populations in MA?

• Hunter/trapper satisfaction and ability • Habitat suitability or management • Public complaints • Vehicle collisions • Public perception of the population • Public perception of management options

26. Describe the recovery of beaver populations in MA from 1928 to the present (as described in the article by Langlois and lecture in class).

Elminiated form MA by hunting/habitat loss, then reappeared in 1928, people pumped about it. Then no predators (wolves) or diseases, or competition so they exploded. People pissed, hunting/exclosure sound good again.

27. What was Question 1, and what effect did it have on trapping furbearers in Massachusetts?

? Question 1 – “Wildlife Protection Act • Banned use of footholds and body-gripping traps • Dramatic drop in beaver harvest – dramatic increase in population.


Limited most effective way of pop control and study conducting.

28. How do the U.S. Fish & Wildlife Service and Canadian Wildlife Service estimate waterfowl abundance?


Waterfowl Breeding Population & Habitat Surveys : • Conducted in May and June • Aerial surveys along transects with a sample of ground/helicopters counts to estimate visibility bias • Count number of ducks and ponds

Production & Habitat Surveys: • Conducted in July • Aerial & ground surveys (not concurrent) • Only a portion of strata surveyed • Number of duck broods (brood index) & number of ponds

30. How does the USFWS determine how many waterfowl were harvested?

Annual Waterfowl Harvest Surveys – (2 parts)

 Part I.  HIP Harvest Information Program FWS selects a random sample of migratory bird hunters & asks them for information – Kind and number of migratory birds hunted – Used to estimate total harvest.

Part II: Cooperative Parts Collection Survey Sample of successful hunters asked to mail in 1 wing from each duck & tail from each goose harvested

31. Explain how the Migratory Bird Treaty Act structures how the U.S. government regulates waterfowl harvests?

• MBTA made it unlawful to hunt, kill, or possess migratory birds except as permitted by regulations set by the Secretary of the Interior.

• MBTA authorizes the Secretary to determine when, if at all, to allow the hunting of  birds.  SEASON IS CLOSED UNTIL OPENED

• MBTA does not prohibit States from making or enforcing regulations, provided such regulations are not more liberal than those approved by the Secretary

32. Identify and briefly discuss the two categories of annual regulations for waterfowl management.

Framework Regulations:

 • Framework Dates – Set for each flyway & states select dates within framework when waterfowl most abundant

 Season Length – May not exceed 107 days for migratory birds

• Daily Bag Limit – varies by flyway & highly variable in response to population estimates

• Shooting Hours – ? hr before sunrise to sunset

• Season length & bag limits – cornerstones for managing harvest of migratory birds


Special Regulations :

• Zoning & Split Seasons • Closed seasons for low abundance species (e.g. harlequin duck) • Special Seasons – focus on under?harvested species or opportunities for special user groups • Quotas also used for limited resources (e.g. some Canada goose & sandhill cranes populations)

33. What is the mallard fall flight index and what goes into estimating it?

• Estimated size of mid?continent mallard population (traditional survey area + MI, MN, &WI) for the fall migration

• Calculated based on: – Breeding population size – Habitat conditions – Adult summer survival – Projected fall age ratio (young/adult)

34. Briefly discuss what types of activities/parameters are managed/controlled by the framework regulations.

When (time, dates) and amount (bag limit).

35. Describe Adaptive Harvest Management and why it was developed.

Goal: “Adaptive harvest management describes the ability to make a sequence of decisions, in the face of uncertainty, that is optimal with respect to a stated objective, recognizing some constraints” (D. R. Anderson) • Managing in the face of uncertainty with a focus on its reduction.

36. Identify the four steps in the Adaptive Management Feedback Loop?

• Monitor – Estimate resource status

• Learn (reduction in structural uncertainty) – Compare predictions to estimates – Update model weights

• Predict (Structural Models) – Model?specific predictions of effects of management given resource status

• Manage – Implement management alternative maximizing objective(s) based on resource status and model weights

37. What are the “key components” of Adaptive Harvest Management?

• Limited number of regulatory alternatives (flyway specific season lengths, bag limits, framework dates)

• Set of population models describing various hypotheses about effects of harvest & the environment on waterfowl abundance

• Measure of reliability for each population model (weights)

• Mathematical description of the harvest management objectives by which harvest strategies can be evaluated

38. Discuss the sources of uncertainty that affect Adaptive Harvest Management for waterfowl.

 Environmental Stochasticity ? e.g., weather, habitat

• Partial Observability ? Uncertainty about population status

• Partial Controllability ? Decisions only partially control actual magnitude of actions

• Structural Uncertainty ? Relationship between management action and population status/response

39. What key variables are used by the USFWS to determine the optimum harvest strategy for midcontinent mallards?

Harvest strategy derived using combinations of: – Breeding population size – Environmental conditions – Model weights Assesses which model best describes the dynamics of the managed populations.

40. Briefly identify the four AHM models that are tested for waterfowl abundance and harvest.

• 4 models of population dynamics – Mortality: Additive vs. compensatory – Reproduction: Strong vs. weak density dependence

42. What is ‘probability of detection’ and how is it used in distance sampling methodologies?

Probability of detecting an animal, given that it is at a distance x from the line. Assumes animals closest to line are more likely to be detected.

43. What are the assumptions for distance sampling methods?

• Lines are randomly located in the study area

• Animals on the line are certain to be detected [g(0) = 1]

 • Detected animals do not move in response to the observer before detection

• Distances are recorded without error

 • Detection curve has a ‘shoulder’

 • Detections are independent events

 • Animals are counted only once from a single line

44. If census techniques yield better estimates of elephant abundance why would wildlife agencies consider using strip (fixed-width) or distance sampling instead?

Easier, cheaper, quicker, etc.

45. What is statistical ‘power’ and why is it an important concept for the conservation of wildlife populations?

The probability that a test correctly rejects the null hypothesis. 1- # of type II errors.  How good is your monitoring really at being right?

46. What are the assumptions of the Leslie Method for Catch-per-unit-effort (CPUE) estimating of wildlife population abundance or density?

• Closed population

• Probability of capture is equal

• Probability of capture is linearly proportional to the effort extended for the sample

47. Explain what statistical function is used to estimate population abundance using the removal (CPUE) method.

• The simultaneous analysis of 2 or more variables

 • Estimate the relationship of one variable with another in terms of a function

• To predict values of one variable in terms of the other

48. What are some situations where the removal (CPUE) method would be a good option for estimating abundance?

Leslie – linear relation between CPUE and Nt • Used when a significant proportion of population is removed


DeLury – non?linear relation between CPUE and Nt • Used when the proportion of the population taken by a unit of effort is small (i.e. 0.02)

49. What is Strategic Habitat Conservation?

1. A structured way to critically thinking about what we do and why we do it; or

2. Setting explicit objectives for populations and then systematically figuring out how to achieve them most efficiently using our own resources and by working with partners.

50. Explain why the USFWS and USGS adopted the Strategic Habitat Conservation approach to get away from “…grabbing the low hanging fruit.”

Could happen cause: • Advancements in conservation theory • Geospatial technologies • Increasing emphasis on accountability Increasing the effectiveness & efficiency of achieving conservation objectives

Did happen cause: • A shift in the overarching aim of conservation to system sustainability 

  • A shift in emphasis from the project scale to the landscape scale

• More science?intensive approaches to planning – Model?based – Spatially explicit – Predictive – Outcome?based  vs. activity?based goals and objectives

 • An ever?increasing emphasis on biological accountability • An emerging emphasis on socially viable solutions (socio? ecological sustainability)

51. List and briefly describe the functional elements of Strategic Habitat Conservation

• Biological planning

• Conservation design

 • Conservation delivery

 • Decision?based monitoring

• Assumption?driven research

52. Explain the difference between “activity-based” and “mission-oriented” conservation objectives and provide an example of each.

Example: activity-based objectives (Focused on actual numbers, precise) –  Protect and restore 20,000 acres of bottomland hardwoods in the Mississippi Alluvial Valley


Example: mission-oriented objectives (Overarching) – Reestablish and maintain three viable sub?populations of LA Black Bear in the Tensas Basin, Red River Backwater, and Atchafalaya Basin of Louisiana.

53. What are the benefits of Strategic Habitat Conservation?

• Better communication among programs and externally

• Records of decisions

• More credibility

• Greater efficiency

 • Greater capacity for leadership in conservation community

 • Strategic research and monitoring

 • Accountability

54. Define “biodiversity” and describe the three levels of biodiversity (not to be confused with the three types of diversity).

“Is the variety of life and its processes; and includes the variety of living organisms, the genetic differences among them, and the communities and ecosystems in which they occur.”

55. Explain how human biology can get in the way of rational decision-making about species conservation.

We like things that are big and look like babies, but are less driven to help small, not cute things no matter how important they are ecologically.

56. Give four examples of how biodiversity is linked to human welfare.

Penicillin, disease tolerant rice species, spider goats, horseshoe crab blood in endotoxin testing makes things safer.