Island syndrome

Island syndrome describes the differences in morphology, ecology, physiology and behaviour of insular species compared to their continental counterparts.

Conversely, birds and reptiles tend to exhibit insular gigantism, exemplified by the moa, cassowary and Komodo dragon.

[10] Insular populations of barn owl have shorter wings, representing a transitional stage in which their capacity for flight is being reduced.

Additionally, the low biodiversity of insular ecosystems makes species recognition less important so species-specific coloration is under less selection.

[12] A subspecies of the chestnut-bellied monarch endemic to the Solomon Islands, Monarcha castaneiventris obscurior, exhibits polymorphism in plumage color: some birds are black with a chestnut-colored belly while others are completely melanic.

As such, reduction in relative brain size is often seen in insular species as this reduces basal metabolic rate[15] without increases in predation risk.

[10] Due to lack of predation, insular species tend to become more docile and less territorial than their continental counterparts (sometimes referred to as island tameness).

[2][19] Deer mice, song sparrows and bronze anoles all have smaller territories with greater overlap compared to their mainland conspecifics.

Falkland Island foxes and Tammar wallabies have both lost an innate fear of large predators including humans.

Due to reduced biomass of large herbivores, several island plants lose protective spines and thorns as well as decreasing the amounts of defensive chemicals produced.

For example, when humans first introduced dogs, pigs, cats, rats, and crab-eating macaques to the island of Mauritius in the 17th century, they plundered dodo nests and increased interspecies competition for the limited food resources.

Based on its robust jaw and cervical vertebrae, Hatzegopteryx is thought to have hunted in a similar manner to modern storks by attacking prey that are too large to swallow whole.

The term "reversed island syndrome" (RIS) was first used by Pasquale Raia in 2010 to describe the differences in morphology, ecology, physiology and behaviour observed in insular species when population density is either low or fluctuating.

[28] The latter improves male reproductive success by increasing the likelihood of winning sexual conflicts over females and augmenting sperm quality.