An initial study published in 1988 by a researcher from Oak Ridge National Laboratory demonstrated the then-current population of 180 horses was over-grazing the island.
The researcher recommended reducing the herd size to between 49 and 73 animals, which she contended was the maximum size that the island could support without environmental damage.
The study showed that the horses were significantly reducing plant stocks on the island, and reducing future plant production due to trampling.
A 1991 study of genetic variation in feral horse herds on eastern US barrier islands was conducted by researchers from the University of Georgia and University of Kentucky.
The study concluded that a herd of 122 was the minimum size necessary to prevent inbreeding.
The researchers noted that they were looking at herd size solely as it related to genetic variation, and did not take environmental damage into consideration.
In addition, it was found that due to the large amount of introduced blood from outside horses, the Cumberland Island horses were not genetically unique.
Due to this, and the ongoing environmental damage, it was concluded that the horses met neither the genetic nor the environmental requirements for feral horses on public lands and that the herd should be reduced or removed completely.
The researchers conceded, however, that their analysis did not take "local historical and cultural elements" into consideration, only environmental and genetic.

In 1995, the NPS began the process of developing a management plan for the Cumberland Island horse.
After compiling information, they released a draft environmental assessment in early 1996 and began taking public comment on a potential management plan.
Public opinion was severely divided, with environmentalists approving of the management plan, which would have likely resulted in the reduction or removal of the herd, and animal rights activists and island residents protesting the plan.
However, before a plan could be implemented, US Representative Jack Kingston included a provision in a federal appropriations bill that prevented any management of the horses.
Kingston made the change to the bill after touring the island, but without consultation with the NPS.
He initially claimed that he personally did not see significant damage to the island from the horses and that the herd size had decreased.
However, upon later questioning, he refused to expand upon his observations of the damage to the island.
The provision expired in 1997, but effectively halted momentum toward a park management plan.
The study published in 2000 recommended a management strategy that reduced herd populations to environmentally-recommended sizes through a combination of off-island adoption to private owners and contraceptives.
The researchers recommended that contraceptive use be focused on the female members of the herd, due to the high numbers of bachelor stallions.

In 2009, a study was conducted by the Warnell School of Forestry and Natural Resources at the University of Georgia to determine public opinion on the management of the feral livestock (horses and pigs) on the island.
The researchers found that 68% of visitors believed the horses were damaging the habitat of the island, there was no consensus on a solution to the problem.
The majority of visitors tended to prefer non-lethal methods of managing the population, as opposed to non-management or complete eradication.
At that time, park management felt that although the horses were popular with tourists, they were also destructive to beach ecosystems, including an increase in erosion where horses had eaten grasses that previously held sand in place.
The 2009 NPCA report emphasized the negative impact that the horses were having on the island environment, and endorsed study findings that between 50 and 70 animals would be an appropriate population for the island.
However, the report also noted the management challenges resulting from the "public and political appeal for the animals", but stated that a management plan is necessary.
Potential solutions
An initial study published in 1988 by a researcher from Oak Ridge National Laboratory demonstrated the then-current population of 180 horses was over-grazing the island. The researcher recommended reducing the herd size to between 49 and 73 animals, which she contended was the maximum size that the island could support without environmental damage. The study showed that the horses were significantly reducing plant stocks on the island, and reducing future plant production due to trampling. A 1991 study of genetic variation in feral horse herds on eastern US barrier islands was conducted by researchers from the University of Georgia and University of Kentucky. The study concluded that a herd of 122 was the minimum size necessary to prevent inbreeding. The researchers noted that they were looking at herd size solely as it related to genetic variation, and did not take environmental damage into consideration. In addition, it was found that due to the large amount of introduced blood from outside horses, the Cumberland Island horses were not genetically unique. Due to this, and the ongoing environmental damage, it was concluded that the horses met neither the genetic nor the environmental requirements for feral horses on public lands and that the herd should be reduced or removed completely. The researchers conceded, however, that their analysis did not take "local historical and cultural elements" into consideration, only environmental and genetic.
In 1995, the NPS began the process of developing a management plan for the Cumberland Island horse. After compiling information, they released a draft environmental assessment in early 1996 and began taking public comment on a potential management plan. Public opinion was severely divided, with environmentalists approving of the management plan, which would have likely resulted in the reduction or removal of the herd, and animal rights activists and island residents protesting the plan. However, before a plan could be implemented, US Representative Jack Kingston included a provision in a federal appropriations bill that prevented any management of the horses. Kingston made the change to the bill after touring the island, but without consultation with the NPS. He initially claimed that he personally did not see significant damage to the island from the horses and that the herd size had decreased. However, upon later questioning, he refused to expand upon his observations of the damage to the island. The provision expired in 1997, but effectively halted momentum toward a park management plan. The study published in 2000 recommended a management strategy that reduced herd populations to environmentally-recommended sizes through a combination of off-island adoption to private owners and contraceptives. The researchers recommended that contraceptive use be focused on the female members of the herd, due to the high numbers of bachelor stallions.
In 2009, a study was conducted by the Warnell School of Forestry and Natural Resources at the University of Georgia to determine public opinion on the management of the feral livestock (horses and pigs) on the island. The researchers found that 68% of visitors believed the horses were damaging the habitat of the island, there was no consensus on a solution to the problem. The majority of visitors tended to prefer non-lethal methods of managing the population, as opposed to non-management or complete eradication. At that time, park management felt that although the horses were popular with tourists, they were also destructive to beach ecosystems, including an increase in erosion where horses had eaten grasses that previously held sand in place. The 2009 NPCA report emphasized the negative impact that the horses were having on the island environment, and endorsed study findings that between 50 and 70 animals would be an appropriate population for the island. However, the report also noted the management challenges resulting from the "public and political appeal for the animals", but stated that a management plan is necessary. Potential solutions 
Cumberland Island horse