The dodo was a flightless bird that lived on the island of Mauritius in the Indian Ocean. Dodos became extinct in the late 1600s, within 100 years after humans first set foot on Mauritius. Being flightless and fearless of humans made dodos vulnerable to human activities. So what did dodos do to try to survive in the face of human threats?
Key Facts About Dodos
Here are some key facts about dodos that provide context on their survival abilities and challenges:
- Dodos were flightless birds around 3 feet tall and weighing over 20 pounds. Their wings were tiny and weak.
- Dodos likely evolved to be flightless due to lack of natural predators on Mauritius.
- Dodos had few natural defenses. They lacked fear of humans and could not fly away from danger.
- Dodos inhabited Mauritius for millions of years before humans arrived in the 1600s.
- Portuguese sailors were likely the first humans to set foot on Mauritius and encounter dodos in 1507.
- Dodos were extinct by the late 1600s, less than 100 years after human contact.
As flightless, fearless birds that had evolved for millions of years without predators, dodos were highly vulnerable once humans discovered Mauritius. So what natural defenses did dodos have, and what did they do to try to survive the new threat of humans?
Dodos Relied on Camouflage and Thick Plumage
Since they could not fly away from danger, one of the main survival strategies of dodos was camouflage. Dodos had thick gray and brown plumage over much of their body:
- Their feather coloring provided camouflage in the forest and scrub habitats of Mauritius.
- Thick plumage protected them from biting insects and minor injuries from vegetation.
- Their small wings were covered in long feathers creating a semi-circular cape around their bodies.
- Their plumage was thickest around the rump and tail, perhaps to protect from predators attacking from behind.
Camouflage and thick plumage were passive defenses that helped dodos survive in nature for eons. But these adaptations proved almost useless against human predators and the new threats they posed.
Dodos Had Limited Mobility and Endurance
As flightless birds, dodos also had limited mobility and stamina for escape compared to birds that can fly:
- With short legs and a heavy body, dodos could not run very fast.
- Their stout legs and large feet suggest dodos could deliver strong kicks, but only at close range.
- Fossil evidence indicates dodos may have lived along the coast and foraged in shallow water environments.
- Dodos likely had enough endurance to swim and walk moderate distances, but could still be run down by human hunters.
The dodo’s terrestrial nature put it at a big disadvantage compared to flying birds that could easily escape danger. Dodos simply could not cover enough ground, either on land or in water, to flee from determined human hunters and invasive species.
Dodos Had Natural Defenses Against Other Species
So in some ways, dodos were well adapted to survive in their island ecosystem before human arrival:
- Thick skin and bone structure provided defense against bites and injury.
- A thick bill was effective as a weapon and for breaking open fruits and seeds.
- Strong legs and claws helped them establish territories and compete for mates.
- A thick gizzard allowed them to swallow large fruits and stones to digest food.
These adaptations helped dodos survive attacks or competition from other Mauritian fauna. But against direct human predation and novel invasive species, the dodo’s native defenses were insufficient.
Dodoes Retreated to Remote Areas
As human activity on Mauritius intensified in the 1600s, surviving dodos apparently retreated to the wildest and most remote areas of the island:
- Humans started settling coastal areas first, pushing dodos inland.
- Remaining dodos took refuge in highland forests, marshlands, and rugged southeast areas.
- This remote habitat provided protection from overhunting and competition from invasive species.
- There are reduced reports of dodos from settled lowland areas over time.
- The last refuge was likely the southeastern swamps before extinction.
Seeking refuge far from human activity helped some dodos survive longer. But eventually humans exploited most of the island, leaving dodos with nowhere left to hide.
Some Dodos May Have Become Nocturnal
Another potential survival adaptation was becoming more active at night than daytime to avoid humans:
- Some accounts indicate that dodos became increasingly nocturnal in areas with human activity.
- Being active at night would reduce encounters with hunters.
- Nocturnality could also have reduced competition from diurnal invasive species.
- It may have disrupted natural feeding cycles, contributing to population declines.
- But night-active behavior could explain why some dodos survived longer in marginal habitats.
Shifting daily cycles to avoid humans offered individual dodos temporary escape. But island-wide overhunting and species introduced by colonists eventually overcame this adaptation.
Dodos Had Almost No Defense Against Introduced Predators
Humans brought many new predators and competitors to Mauritius that contributed to the dodo’s demise:
- Cats, rats, pigs, and monkeys preyed on dodo eggs and young dodos.
- Invasive herbivores competed with dodos for limited food.
- Mongooses attacked dodos and destroyed their eggs.
- Dogs and macaque monkeys harassed and killed adult dodos.
- With no prior evolutionary exposure, dodos had almost no defenses against these novel threats.
Constant predation pressure from invasive mammals was likely a bigger factor in dodo extinction than direct overhunting by humans. Dodos simply had no natural behaviors or adaptations to cope with this onslaught.
Some Dodos Were Taken Into Captivity
A small number of dodos were taken into captivity by early colonists on Mauritius, which actually helped preserve the species longer:
- Live dodos were captured and shipped to zoos and menageries in Europe.
- These captive dodos were safe from overhunting and invasive species.
- Most captive dodos did not survive long due to inadequate care and diet.
- But they remained alive up to a few years longer than wild dodos.
- The last captive dodo died in England in 1681.
Captivity ensured survival of a handful of dodos into the 1680s, over a decade after the species was extinct in the wild. But too few dodos were ever kept this way to establish a lasting captive population.
Dodos Could Not Adapt Quickly Enough
The key reason dodos were driven extinct so quickly after human contact was their inability to rapidly adapt to foreign threats:
- Lack of prior evolutionary exposure meant they had no ingrained defenses.
- With no natural fear, they showed little avoidance of humans and invasive species.
- They could not fly away or outrun exotic predators.
- Hunting and egg predation quickly depleted the small island population.
- Such extreme pressures outpaced the potential for adaptation.
Centuries of isolation left dodos vulnerable to human impacts they were unable to adapt to, despite some attempts to modify behavior. Within a hundred years, these unique birds were gone.
Conclusion
In summary, dodos developed some basic survival behaviors in response to human arrival, but to no avail. Their primary strategy was retreating from populated areas. Some dodos may have become nocturnal to avoid daytime human activity. A small captive population persisted thanks to human care. But in the end, the dodo’s lack of fear, inability to flee threats, and evolutionary naivete to invasive species rendered them incapable of adapting rapidly enough to survive the human onslaught on Mauritius.