The Icelandic population today derives from 35 animals that were set ashore in the north east of Iceland in 1787.  Possibly another 35 animals set a shore in Eyjafjörður in the north, integrated later into this founder population.  A comparison study between the Icelandic reindeer population and semi-domesticated reindeers from Norway suggested that founder effects were highly active in determining the genetic structure of the population (Røed et al. 1985).  The results further implied that the genetically effective founder population was possibly less than 15 animals. 

So far, the effect of this genetic bottleneck has not influenced the body condition or fertility of the population noticeably.  In general natural mortality is low, and fertility and calve survival are high. 

Because of its isolation Iceland lacks many of the normal threats that haunt continental species. The island has no large predators and insects, parasites and diseases are few and not of consequence to the population so far.  These protected surroundings together with low genetic variability in the Icelandic reindeer population, makes them especially vulnerable to possible future ecological changes.

Harsh winters with widespread non-penetrable ice crust and lack of available food source have so far been the main reason for high mortality in singular years.  Severe winters were common in the last half of the 19th century and the beginning of the 20th.  In this period the population declined rapidly and disappeared from large areas.  Probably only a few hundred animals survived and the population may have gone through another genetic bottleneck. 

Possible climate changes with consequential changes in vegetation and food availability might affect the population in future.  In the last ten years or so the winters have been mild with above average winter temperatures and little snow.  So far these climate changes seem to increase winter and early calf survival.  In the long run mild winters can mean more ice with possible non-penetrable ice cover and less snow.  Less snow might again mean more exposed overgrowth and faster withering of vegetation during summer because of dryer soil. 

Human caused disturbances and land use activities such as roads and industrial projects have already fragmented the reindeer habitat somewhat with potential cumulative effects that have yet to be revealed.  National parks and better roads have lead to increased access and more traffic which again will lead to increased disturbance.  Numbers of animals that are killed in the traffic have increased noticeably and might continue to rise in future.  Little is known of how sensitive the Icelandic reindeers are to human disturbance. Originating from semi-domesticated animals and living for more than 200 years in predator free surroundings might make them more relaxed to human caused disturbance.  On the other hand heavy annual hunting pressure is likely to keep them on their "toes" around human settlement and sensitive to stress cause by human activities.