|Have you ever visited Gold Butte National Monument (GBNM) during summer? There is no way to sugar coat it: to us, the heat is brutal and unrelenting! Now imagine that this is where you live. For the plants and animals that live in GBNM, survival depends on various physical adaptations and behavioral strategies. The key to surviving the heat is directly related to obtaining water and retaining it once you have it. |
To obtain water in GBNM, plants basically have two strategies. Some plants, such as cactus, have a widely dispersed, shallow, sponge-like root system that can absorb water quickly just after raining and before it evaporates away. This method is useful during short rains like when a small thunderstorm passes over and only a small amount of water falls on the ground. Other plants have roots that go deep underground and tap into pockets of moist soil or groundwater. Mesquites, for example, have roots that can go 100 feet deep. Creosote bushes use both methods. Some plants have special tricks. For example, yucca leaves are channel shaped to help funnel water towards the roots, thus increasing the amount of water the plant can capture.
For retaining water, plants have a wide variety of strategies. First, some plants, like some Perennials, go dormant during summer by dropping their leaves and reducing their metabolic activity. The best example of this is the Ocotillo plant. Yes, there are pockets of native Ocotillo at GBNM. Many people who have Ocotillo at their homes would swear that their Ocotillo was dead, only to see it come back to life after a rainstorm. Summer dormancy is one reason many desert plants, like the Ocotillo and Joshua tree, are slow growers. The extreme of this strategy is what Annuals do: they die at the end of every growing season. Before they do, however, they produce large numbers of seeds that are heat tolerant and germinate back to life when conditions are right. Some seeds remain dormant for several years in order to have a better chance that some of them will survive to maturity.
|Many plants evolved to eliminate their leaves completely or have very tiny leaves. Large leaves make it hard to retain water, and so can become a detriment. The spines of cacti are really modified leaves. In plants that hold onto their leaves, like Creosote Bushes, the leaves are covered with a waxy substance that minimizes water loss and reflects sunlight. Some have leaves that are tough to begin with. Some plants are able to store large amounts of water in their roots and tissues. The California Barrel Cactus is a good example. It can store and retain large amounts of water in its fleshy tissue within the stem or barrel, but don’t try to drink it — cactus put poison in their water. |
The ability to store water might seem a good survival strategy, but it won’t help much if animals eat you for your moisture. Many animals at GBNM do not get their water directly from springs or water pockets. They will drink if the opportunity is there, but in most instances, the springs and water pockets will be dry or just too far to travel. For many of the prey animals, such as insects, mice, antelope squirrels, and rabbits, their primary source for water is from eating plants. Predator animals, in turn, obtain their water by eating prey. So besides eating as much as you can, the real trick is to evolve characteristics and behaviors to retain as much water as possible.
The most obvious method to retain water is to avoid the hottest part of the day. The human citizens of Mesquite are familiar with this strategy — we do our chores at night or get up early in the morning when temps are low. Many animals, like the Mojave Sidewinder, become nocturnal as the temps rise. By July, many animals only come out of their burrows well after sunset. Some animals, like the Desert Tortoise, go into a state of inactivity similar to hibernation called brumation. After feasting on cacti, grasses, and wildflowers, tortoises can retreat into a burrow for the entire summer and not emerge until temperatures are cooler in the fall (except they will come out during summer to drink rainwater). Tortoises rely on their ability to retain urine and recycle the moisture in the body. For a tortoise, their bladder is like a canteen, but they will spray the noxious fluids on a predator in a last ditch effort to defend themselves. One should never approach or handle a tortoise for this reason unless it is on a road and in eminent danger of being run over. It can be fatal for a tortoise if it urinates while being handled by people.
|Larger animals like Mule Deer and Desert Bighorn migrate to higher elevations where they find cooler temperatures and standing water. Some birds of prey, like Golden Eagles, will fly higher where the air is cooler. Even animals that are active during the day seek shade and shelter when possible. Lizards, when forced to come out into the open sun, will extend their legs to get their body off the rock surface as they scurry to another shaded spot. Kangaroo Rats store dried seeds in their burrows. The seeds absorb moisture in the air from the K-rat’s breath, and thus the K-rat is able to recover some of the moisture lost while breathing.|
Even with these adaptations, a portion of the plants and animals die from dehydration every summer. The summer drought of 2020 posed a great hardship for many plants and animals and led to higher than normal mortality rates. For example, a large number of Joshua Trees suffered damage and death from horses, rabbits, and rodents gnawing deep into their trunks seeking moisture. Similarly, rodents killed many cactus plants. High mortality in prey populations will eventually translate into higher mortality in predator populations, as there will be less food for them. Observations by the author of predator species this year are much lower than during the previous four years.
Life at GBNM evolved over millions of years, and it has been a desert for about 10,000 years. Many species have endured changing conditions to arrive at the environment we have today. Countless other species have perished when they could not overcome the various challenges through the ages. We face another global challenge today as our climate undergoes changes due to the ever increasing concentration of carbon dioxide in our atmosphere. Other challenges include the spread of non-native species, pollution, and diseases to name a few. Sadly, all of these challenges are, to a large degree, attributable to humans. The populations of many species in our area are declining, but we can be a part of the solution. All of us can play a role and contribute towards protecting and preserving our environment.