(chris) 19. Ungulate population dynamics and managements

Question 1

Deer most widespread Ungulet

Answer 1

Massive introduction effort in 19th centuary

Deer legaly protected up till 1923

Hunting qoutas introduced in 1923

(Pay for license - bag limit)

Deer populations continued to grow quickly and people became concerned about impacts on vegetation

Question 2

By mid 20th centuary…

Answer 2

Understorey depleted

Question 3

Deer declared pests in ____ ?

Answer 3

1932

• Unlimited hunting legalised
• Government recruited professional deer hunters
• By 1954 - 2mil deer culled
• Much of NZ’s hut and track network designed to give cullers access to rural areas

Question 4

Market for venison and deer velvet doomed…

Answer 4

the government deer culler

Question 5

1960’s led to growth of game meat industry

Answer 5

• Effectiveness of commercial hunting meant less work for deer cullers
• 1970-80’s led to live deer recovery for farming, using helicopters

Question 6

Problems caused by recent deer over population in eastern USA

Answer 6

Damage to crops & gardens

Road accidents

Deer in NA carry ticks that transmit Lyme disease to humans

Question 7

One of main causes of deer explosions in eastern USA…

Answer 7

Is local extinction of big carnivores

Question 8

Wolves are only predator that predate on moose at Isle Royale.

‘Delayed density dependance’

of prey and predator survival and reproduction

Answer 8

A. High numbers of prey > Predator population responds (increase)

B. Increase in predators reduces survival of prey (decrease)

C. Prey picking up after predator population has crashed (carrying capacity)

Lag caused by.. gestation (one year)

Density dependant wolf predation regulates moose numbers on Isle Royale

Question 9

Trophic cascade

Restored wolves, influence deer behaviour and reduce browse in Wisconsin

Question 10

Natural enemies of herbivores keep terrestrial ecosystems green

Most terrestrial ecosystems ‘green’ because:

Answer 10

• Carnivores, parasites and pathogens keep herbivore populations down
• So vegetation usually under weak herivore pressure in natural ecosystem

Question 11

What limits ungulate abundance in New Zealand ecosystems?

Was this decline down to hunting and professional cullers?

Answer 11

Mostly no, Animal condition and fucundancy tells us this.

Trend in deer carcas weight

Deer condition is poorest when deer abundance is high and on the decline.

Deer are hungry and fertility is low because low % of them are lactating.

Suggests carry capacity over shot, lack of food led to decline.

(Red deer quickly depleted their preffered species throughout NZ, they only eat particular plants as it suits their diggestive system more.

THEY CAN ONLY GROW FAT AND INCREASE POPULATION WHILE HIGH QUALITY FORAGE AROUND

STRONGLY FOOD LIMITED DURING DECLINE

Question 12

What about this second decline?

Answer 12

Deer doing better in weight so must be more forrage around.

Reason for decline is heli hunting.

Question 13

Can recreational hunting ever keep deer density below levels causing unacceptable damage?

(where they don’t wreck the forest under storey)

Answer 13

It depends..

Heavy hunting pressure keeps fallow deer at low densities in Te Miro and Te Tapui

Recreational hunting ineffective at controlling sika deer in Kaimanawa and Kaweka ranges. (every second step deer pellets)

Question 14

Abundance of sika deer remains high in Kaimanawa and Kaweka ranges, despite decline of red deer after depletion of preferred plant species.

-Hurting regenration of beech species (canopy-forming trees)

Answer 14

-Aerial culling used to control sika in Kaimanawa and Kaweka range

Question 15

Lower nutritional requirements enabled sika to invade forests in Kaweka ranges already depleted by red deer.

Graph charts the invasion of seeka deer through the years

(Red deer used to be main species)

Question 16

Fenced plots in area subjective to heavy, medium, low intensity culling

In all cases seeds growing alot faster inside the fence than outside

Question 17

Determinants of success of recreational hunting in controlling deer populations?

Answer 17

Depends on

• Ease of access to most of the reserve (entry points)
• Number of hunters living within 90km radius

(hence why kaimanawa and kaweka ranges doesnt work)

Question 18

NZ flora and vegetation not especially vulnerable to ungulate browsing

• Many natives plans unnatractive to deer
• Forests regenration can be heavily impacted by over abundant deer populations even in their native ranges

Question 19

Key role of predators in regulating ungulate populations in their natve ranges

-Lack of predators main reason for dramatic impact of ungulates in New Zealand

Question 20

Widespread depletion of preferred browse species caused mid 20th centuary decline of deer nation wide

-Recreational hunting and culling on foot had little effect

Question 21

More efficent commercial helicopter hunting further reduced deer populations in late 20th centuary

-Resurgance following cessation (end process)

Question 22

Recreational hunting can control populations in reserves close to large human populations with easy access

-Ineffective in less accessible areas, where professional control needed to limit damage.