16: Impacts of introduced ungulates and marsupials on New Zealand ecosystems Flashcards
Which are the most widespread in New Zealand?
Red Deer and feral goats
How many introductions efforts of red deer throughout NZ?
> 220
If deer populations are low, they only eat..
..only eat their prefered species.
But uncontrolled deer populations may increase, exerting more browsing pressure. The preferred species depletes and they start to eat non-preffered species.
Most long-lived overstorey trees are unnatractive to deer therefore they can renenerate…
at low deer densities
Why is Kamahi an important exception to long-lived overstorey trees?
Most long lived overstorey trees are unnatractive to deer so they regenerate at low deer densities.
Kamahi however, is an important exception as deer like it
If there is no deer control (hunting pressure) what are the consequences?
Understorey completely stripped
Do goats stick strictly to their preffered species when it is abundant?
No. Goats nibble on a wide variety of plants even if their preffered species are still available.
What is the purpose of exclosure plots?
Exclosure plots are designed to keep ungulates out (1.8m atleast for deers)
When were pigs introduced to NZ and what are their trates?
1769
Famously omnivorous
Not ruminants, not efficent at digesting cellulose
Versatile opportunistic shown by studies of pig diet on Auckland island
- Marine algae
- Summer green herbs
- Earth worms
- Snow tussock
Browsing and grazing
Foraging on the ground
Rooting
Pigs are major ____ _________ in podocarp - broadleaf forests?
Seed Predators
How to pigs aid in the disperal of some native tree seeds?
57% damaged and undamaged seeds fed on by pigs went onto germinate from faeces
(they mostly swallow them whole and do not crunch)
A major cause of the decline of the Kauri snail is?
Pigs eat them
They dig up large quantities of earth worms and beetle larvae
How are pigs a danger to native frogs?
Although pigs do eat frogs occasionly, the biggest threat they cause is the destruction of habitat around streambank habitats by rooting.
What is the public attitude to feral pigs?
(Conservationists, Hunters, Farmers)
Conservationists: Control or eradication of feral pids is important for conservation of native biota
Hunters: Prized game meat
Farmers: Pigs predate on lambs near forest edges
How many introduced marsupials in NZ?
7 in total
6 - Wallabies (2 on mainland)
1 - Possum
Why was the possum introduced?
- Fur trade hopes motivated widespread introduction of possums
- They now occupy virtually all nz terrestrial environments
- Widespread damage to forest canopies noted mid 20th century
Possums can kill canopy trees by repeatedly…
browsing soft new leaves
What protective measures are in place to stop possums eating native mistletoe?
Banding the trunks with metal bands to stop them climbing.
(Possum browse probably one factor in the extinction of a red mistletoe species last seen in 1954)
Possums also prey on eggs, nestling and even adults of many native bird species.
Name as many species as you can.
Kokako (serious threat)
Kaka and kea
kereru
Kiwi
Harrier
Fantail
Which native invertebrates to Possums eat?
Powelliphanta snails (60 in one night, cowan 2011)
Wide range of insects
- Stick insects
- Cicadas
- Wetas
- Beetles
- Flies
Wallabies have a __________ diet, they are mainly ______ but also ______ tree seedlings alot.
A. Herbivorous
B. Grazers
C. Browse
Where in New Zealand can the worst impacts of Wallaby’s be found?
Kawau island
How can you tell the species diet preference?
compare availability and diet
see which species are over represented in the diet
