Kangaroos mainly die due to a lack of nutrition, getting killed by other animals such as dingoes, foxes, eagles, cats, human activity, and becoming victims of diseases. Mortality in kangaroos is furthermore affected by bushfires.
Lack of nutrition
The lack of nutrition is, by far, the major reason why kangaroos die. The lack of nutrition is often caused by tooth wear and external factors such as extreme drought.
Young kangaroos have a lack of reserves
Poor food availability especially affects young kangaroos. Seasons of extreme drought dramatically reduce the availability of sufficient nutrients. While grown-up red kangaroos can perfectly adapt in the dry areas of the Australian continent, especially weak and young animals cannot withstand the harshest conditions. A lack of nutrition is the main reason that causes mortality in young kangaroos that only recently got weaned. They have a lack of reserves. A lack of nutrition also affects joeys that live in their mother’s pouch. Poor feed availability leads to survival rates of joeys that are less than 15 %.
Extreme tooth wear leads to a lack of nutrition
Extreme tooth wear mainly affects elderly kangaroos. Tooth wear leads to the inability to cut grasses which ultimately leads to a lack of nutrition. The animals become weak and vulnerable and eventually prone to infections. Weak animals are also easy prey.
Predation by humans and animals affect kangaroos, wallabies, wallaroos, and quokkas. Red and grey kangaroos react differently to predation. Studies show that red kangaroos prefer moving in open plains where they can rely on their fast movement. Grey kangaroos, on the other hand, prefer moving in covered areas and undergrowth of scrub.
What are the predators and threats to kangaroos?
Wedge-tailed eagles, dingoes, and foxes are the natural predators of kangaroos. Humans also affect the kangaroo population due to commercial harvesting, roadkill, and habitat loss due to extensive farming and clearing of woodland.
While grown-up large kangaroo species aren’t easy prey for dingos and foxes, younger kangaroos often end up being caught by predators. Joeys have neither the necessary strength and fighting skills, nor the ground speed to escape their predators. Adult red kangaroos are extremely fast on wide-open plains with top speeds up to 56 km/h (35 mph) which means they can escape easily. Younger kangaroos and smaller kangaroo species, however, cannot really escape easily.
In order to catch larger adult kangaroos, the predators‘ team up and hunt in groups. This behavior is common in severe droughts when there are hardly any young kangaroos left, and food for both the kangaroos and its predators is sparse. Besides, old and weak kangaroos are often caught by dingos.
The effects of the dingo fence
The dingo or dog fence in Australia is a perfect example to study the effects of dingos on kangaroos. Inside the protected area there are hardly any dingos, and that helps the kangaroo population. Hence dingos control the kangaroo population outside the protected area. In good seasons, dingos find easier prey like rabbits. Drought, however, reduces the available amount of rabbits, and then dingos start to catch kangaroos.
Kangaroos are excellent fighters
You might have heard about kangaroo boxing and kangaroo fighting. Kangaroo boxing is a ritualized fight to determine the position of a kangaroo within the mob. Read this article on kangaroo boxing to learn more about their rituals that determine the social status.
Kangaroos not only fight to get access to females. Once they leave the pouch, they playfully learn how to fight. That skill comes in handy for their survival in the wild. Whereas joeys are easy prey, adult kangaroos fight for their lives. Male kangaroos, in particular, often successfully fight against dingos and foxes.
Foxes and Cats endanger smaller kangaroo species
The larger species such as the red, eastern grey, western grey, and antilopine kangaroo can effectively fight against foxes and cats.
Numerous smaller kangaroo species such as wallabies, however, are severely affected by dingoes, foxes, and cats. Wallabies and quokkas are significantly smaller than kangaroos and are, therefore, easy prey.
How has human activity affected mortality in kangaroos?
Human activity had and still has a significant impact on the entire kangaroo population. Kangaroos can benefit from man-made water sources for cattle and sheep in the inland areas of Australia. That reduces mortality in extreme drought. Simultaneously humans also destroy the habitat of certain smaller kangaroo species. Smaller wallaby species have become extinct. Commercial kangaroo harvesting and roadkill further influence the mortality in kangaroos.
Habitat loss and fragmentation
Habitat loss and fragmentation have long-term effects on the entire kangaroo population. Intensive agriculture, mass clearings of bushland and woodland beginning in the 19th century brought smaller kangaroo species closer to extinction.
Commercial harvesting of kangaroos in Australia
Commercial harvesting of kangaroos is used to control the kangaroo population. In well-protected areas, the kangaroo population often skyrocketed. This often affected local farmers and made replantation of forests more difficult. The state and territory governments, therefore, publish quotas for harvesting to maintain a certain amount of kangaroos in each area.
The meat is used for human consumption and it is known to be low in fat and high in protein. About 40 % of harvested kangaroos are used to produce meat for pets. Kangaroo leather is another byproduct of commercial kangaroo harvesting.
Common kangaroo diseases
There are hardly any diseases that significantly affect the kangaroo population. Studies on common kangaroo diseases for animals held in captivity mostly showed diseases of the alimentary tract, followed by pneumonia and an infection called toxoplasmosis. An unfavorable environment may lead to weaker animals that become prone to infections. The lumpy jaw infection, for example, has been diagnosed in some dead animals in the wild. Diseases are relatively well monitored due to the inspection of kangaroo meat for human consumption.
Droughts, floods, extreme wet or cold weather weaken the kangaroo population and make it more vulnerable to infections and diseases. Epidemic diseases occur in the kangaroo population from time to time. However, the high mortality rate within a short period of time usually prevents the spread of the disease across the country.
How have kangaroos been affected by bushfires?
Kangaroos have always lived with the imminent threat of bushfires. Kangaroos, larger wallabies, and wallaroos are rather quick animals than can outrun local bushfires. The animals can escape but fires lead to a reduction of grassland and food which eventually leads to a lack of nutrition and increased mortality.
Larger burnt areas make it even more difficult for kangaroos to find food within their known home range. Contaminated water further increases the risk of making kangaroos sick. Bushfires affect kangaroo joeys – they’re not as fast as larger adults and often cannot escape.
How has the 2019/20 bushfire season affected the kangaroo population?
Australia’s catastrophic 2019/20 bushfire season caused severe damage to the country. However, Australia is a vast country and only a small fraction of the continent has been affected by bushfires. This means that local home ranges of kangaroos were completely destroyed but it did not have major effects on the entire kangaroo population. As a consequence, some regions temporarily put their kangaroo harvesting program on hold to help the kangaroo population in affected areas.