An ice age has hit the already cold planet of Ryu 108. Its inhabitants, with the culture and technology of Scandinavia at the height of the viking age, are forced to feed themselves with a drastically reduced amount of arable land. As a result, many who once lived in the planet's more northerly regions are forced to leave or starve, since the south is already overflowing with climate refugees.
Now, around 23,000 of these vikings have decided to leave the planet entirely (space travel in this universe is done by rigging magic crystals to the masts of sea vessels). Eventually, these vikings stumbled upon an uninhabited tropical archipelago "Eyjagard".
Before I discuss Eyjagard, here is what the vikings are bringing with them:
-23,000ish settlers from all segments of society
-Their religion (Norse paganism)
-Their technology (iron weapons, longships, etc.)
-These non-native animals to Eyjagard (livestock, pets, and stowaways): dogs, cats, chickens, pigs, sheep, goats, cattle, horses, ponies, unicorns (same biology and behavior as horses, just add a horn), domesticated woolly mammoths, domesticated woolly rhinos, wargs (domesticated direwolves roughly the size of horses, behave basically like giant dogs), house mice, black rats
-These non-native food crops: barley, wheat, rye, oats, apples
A word about natives
The Eyjagard archipelago is completely uninhabited. Nobody has ever lived there before. However, there are peoples living on other archipelagos throughout Atlantea (Atlantea has no continents but is dotted with several archipelagos, almost all of which are tropical due to Atlantea's proximity to its sun and mountainous due to a long chain of events I don't have time to discuss here). Below are a list of peoples on Atlantea and what you need to know about them:
-Kangaroo Islanders (Kangaroo Islanders hail from Kangaroo Island, a misnomer and the planet's largest archipelago. Far to the north of Eyjagard and without much in terms of seafaring technology, these people will not be very relevant in the immediate future, though they may come into play later if the new Eyjagardians do enough exploring. Their culture and tech is an amalgamation of pre-contact Australian Aboriginal and Papuan cultures).
-Platypusians (From the archipelago of Platypusia to the north of Kangaroo Island, meaning they are REALLY far away, these people will, however, be relevant in the immediate future for one reason: advanced seafaring technology and skills. Their culture and tech resembles that of the Maori from New Zealand).
-Dolphinesians (From the archipelago of Dolphinesia between Eyjagard and Kangaroo Island, the Dolphinesians are the closest natives to Eyjagard. In fact, the Dolphinesians know of Eyjagard's existence, having embarked on numerous fishing expeditions on the northern shores but never establishing a settlement there. The Dolphinesians, like their faraway Platypusian cousins, are highly skilled seafarers and navigators, having established contact with all of Atlantea's tribes and civilizations. Their culture and tech is an amalgamation of various Polynesian, Melanesian, Micronesian, Filipino, and Indonesian cultures, with particular emphasis on Native Hawaiians and Majapahit).
By trading with the natives, the settlers can obtain these new food crops: Bananas, plantains, pineapples, betel nuts, breadfruit, taro, cassava, kava, noni, coconuts, sugarcane, and sweet potatoes
Intro to Eyjagard
While dozens of islands make up the Eyjagard archipelago, there are two that make up more than 95% of the archipelago's total landmass: Nordgard in the north and Sudgard directly southwest of it, separated by a narrow strait. As a result, the shape of the archipelago roughly resembles New Zealand. These islands are roughly equal in size. While both of the islands are highly mountainous, Nordgard's proximity to the equator keeps any snow-capped peaks from forming. Sudgard, on the other hand, is colder and more similar to the viking homeland of Ryu 108, with many snow-capped peaks, glaciers, volcanoes, and fjords.
ECOSYSTEMS: NORDGARD COASTAL RAINFORESTS
Nordgard is the northern and more tropical of the two islands, with no snow-capped peaks, despite having mountains of roughly equal altitude to the colder Sudgard. The lowlands along the coast are hot, humid, and covered in tropical rainforest, with similar vegetation to the real-world islands of Borneo or Java. Most of Eyjagard's arable land is found here. However, an interesting mix of native creatures inhabits these coastal rainforests and shallow waters just offshore:
-Brokey Strait Iguana (Marine Iguana)
-Brokey Strait Finch (Galapagos Finch)
-Bird of Paradise
-Misc. Tropical Fish
-Eyjagard Giant Tortoise (Galapagos Giant Tortoise)
-Green Sea Turtle
-Jungle Hornbill (Papuan Hornbill)
-Jungle Rhino (Sumatran Rhinoceros)
-Eyjagard Iguana (Galapagos Land Iguana)
-Flying Fox (The giant fruit bat, not a literal winged fox)
-Atlantean Penguin (Little blue penguin)
-Atlantean Pelican (Australian Pelican)
-Brokey Strait Penguin (Galapagos Penguin)
-Magpie (Australian Magpie)
-Goanna (Misc. mid-sized monitor lizards)
-Eyjagard Fur Seal (Galapagos Fur Seal)
-Magnificent Langskip (Magnificent Frigatebird)
-Eyjagard Alligator (American Alligator)
-Giant Eagle (Philippine Eagle)
-Eyjagard Panther (Florida panther)
MISC. VENOM HAZARDS:
ECOSYSTEMS: NORDGARD HIGHLANDS
Inland as elevations rise, temperatures drop, leading to a climate similar to that of the New Guinea Highlands. However, the humidity from the sea pooling over the mountains has allowed a vast redwood forest to grow here.
-Mountain Elk (Red deer)
-Mountain Camel (Dromedary with the fur of a Bactrian)
-Redwood Devil (Tasmanian Devil)
-Thylacoleo (a MUCH larger version over 6ft tall and 12ft long)
Sudgard is much more uniform than Nordgard, being covered in coniferous forests basically throughout, with the sole exceptions of glaciers and snow-capped peaks. Fjords dot the landscape, as the mountains frequently go all the way to the coasts.
-Southern Moose (Moose)
-South Eyjagard Penguin (Magellanic Penguin)
-Taiga Bear (Short-faced bear Arctodus Simus)
NOW, FINALLY, MY QUESTION
If this is the setup going in, how will the Eyjagardians fare in their new home after 100 years? How would their invasive species screw up these ecosystems and/or lead to the extinction of native species? Would they domesticate any native species?