Carrying capacity of white tailed deer

This is a rather old (Potvin and Huot 1983), but interesting study.

White tailed deer

What was found?

• The carrying capacity of a white-tailed deer (Odocoileus virginianus) wintering area was detremined based on food availability and biological characteristics of the animals.

• Estimated carrying capacity could vary between 0 and 18 deer/\(km^2\) depending on sinking depth of deer in a severe winter

• The desirable population in the area studied should be maintained between 15 and 28 deer/\(km^2\).

• The sensitivity of the model to variations in the original values was tested and the possible strategies for management discussed.

How did they do this?

Looked at

• Measurement of the surface area used by deer
• Maps of cover types,
• Estimated accessibility of the browse (integrating biomass)
• Snow depth, and energy cost of walking also included
• Assessment of the nutritive requirements of deer based on published information

Carrying capacity

• The authors defined carrying capacity as “The number of animals a habitat can maintain in a healthy and vigorous condition”
• This differs in some respects from the ecological carrying capacity
• Relevant to management.
• But can be controversial, especially when feeding takes place
• Also subject to legal restraints

Questions

What might a low reproductive rate be due to?

• A population close to or above the carrying capacity? (Harvest more)
• A population below the carrying capacity affected by poor habitat or other factors? (Harvest less)

Challenges

• Condition may be influenced by summer conditions when food is abundant
• Mortality may be determined by winter conditions when food is scarce

Details

Read the paper for more details of how these challenges were addressed.

http://r.bournemouth.ac.uk:82/Ecosystems/papers/Estimating_carrying_capacity_of_white_tailed_deer.pdf

Unintended consequences

• An example from the Serengeti ecosystem in Tanzania (Chauvenet et al. 2011) has some interesting insights.

What did they look at?

• A vaccination campaign against Canine Distemper Virus (CDV) targeted at conserving the African lion (Panthera leo),
• Well meaning, but could affect the viability of a coexisting more threatened species, the cheetah (Acinonyx jubatus).
• Assuming that CDV plays a role in lion regulation, the results suggested that a vaccination programme, if successful, risks destabilising the simple two-species system considered, as simulations show that vaccination interventions could almost double the probability of extinction of an isolated cheetah population over the next 60 years.
• Predictive modelling can be a useful tool in examining the consequence of vaccination interventions on non-target species.
• Need to carefully consider linkages between human-intervention, species viability and community structure when planning species-based conservation actions

The problem

Cheetah life cycle that can be divided into three stages.

• Cubs (up to 12 months old),
• Adolescents(13 to 24 months old)
• Adults (2+ year of age).
• Cheetah females are solitary and occupy overlapping home ranges, while males can be solitary, territorial, and/or form coalitions.
• Maximum number of cubs = 6
• During the first year,and particularly the first two to three months of their lives, cubs are extremely vulnerable to lion attacks
• So interventions to protect lions may place cheetahs at risk

Cheetah populations and lion populations

How was the problem addressed?

• The authors used a model to assess the impact
• Model suggested that cheetahs were less likely to go extinct if viral outbreaks did affect lions
• Lions did not go extinct even without vaccination
• Interventions to protect lions could put cheetahs at risk

Modelled results

Some more unintended consequences

Full paper

http://r.bournemouth.ac.uk:8788/files/webpages/Ecosystems/papers/Chauvenet%20et%20al.pdf

More ideas about management options

(Doherty and Ritchie 2016)

http://r.bournemouth.ac.uk:82/Ecosystems/papers/Doherty_Ritchie_2017_Stop_Jumping_the_Gun.pdf

Landscape of fear

(Miller and Schmitz 2019)

http://r.bournemouth.ac.uk:82/Ecosystems/papers/Miller_Schmitz_2019_Landscape_of_fear.pdf

Landscape of fear

“In recent decades the ‘landscape of fear’ has grown in popularity to become a central consideration in wildlife management, and has even been reconceptualised as the’landscape of coexistence’for understanding human-wildlife conflicts such as predator attacks on livestock. Yet fear effects are not always the predominant driver of predator-prey interactions. Thus, guiding ecological principles have not been assembled to explain the broader food web interactions that shape the context dependency of carnivore-livestock conflict. We address this gap by developing a conceptual framework as a way to think about the contingencies under which inducing non-consumptive ‘fear effects’ on predators would be effective to mitigate carnivore-livestock conflict. The frame-work specifically considers interactions among wildlife (carnivore predators, wild ungulate prey) and humans(people and livestock) in terms of spatial predator-prey assemblages in which the nature of wildlife human interactions,as either a carnivore-livestock conflict or a coexistence food web, is contingent on the nature of spatial movement and overlap of humans and wildlife across landscapes. Considering human-wildlife interactions within such a spatial food web context can assist in enabling people and wildlife, especially imperiled carnivores, to coexist in human-modified landscapes. The framework offers predictions that should be tested via adaptive management experiments that evaluate whether conflict mitigation solutions aligned with particular spatial human-livestock-carnivore contexts do indeed resolve conflict.”

Model

More complex model example

(Jones et al. 2017)

http://r.bournemouth.ac.uk:82/Ecosystems/papers/Jones%20et%20al.%20-%202017%20-%20Mathematical%20models%20for%20invasive%20species%20management%20Grey%20squirrel%20control%20on%20Anglesey.pdf

(Gilpin 1973)

http://r.bournemouth.ac.uk:82/Ecosystems/papers/Gilpin%20-%201973%20-%20Do%20Hares%20Eat%20Lynx.pdf

(Deng 2018)

http://r.bournemouth.ac.uk:82/Ecosystems/papers/Deng%20-%202018%20-%20An%20Inverse%20Problem%20Trappers%20Drove%20Hares%20to%20Eat%20Lynx.pdf

(May 1999)

http://r.bournemouth.ac.uk:82/Ecosystems/papers/May%20-%201999%20-%20Unanswered%20questions%20in%20ecology.pdf

(Alan A. Berryman 1992)