Exhaustive Study Guide on Rangeland Management, Animal Husbandry, and Wildlife Ecology

Factors Influencing Animal Selection on Rangelands

Effective rangeland management requires an understanding of the diverse factors that influence how animals are selected for particular environments. These considerations are critical for optimizing production and maintaining ecological balance. The primary factors include topography, climate, and the specific types of vegetation available on the rangeland. Additionally, livestock managers must account for the water requirements of different species, the presence of predators, and the prevalence of pests and diseases in the region. Economic and social considerations also play a significant role in determining which animals are best suited for a ranching operation.

Topographical features significantly dictate animal suitability. For instance, sloping and rocky terrain is most appropriate for goats and sheep, as these animals are naturally adapted to navigating rugged landscapes. In contrast, cattle and horses are generally less suited for extreme slopes or excessively rocky ground compared to smaller ruminants.

Water Requirements and the Impact of Salinity

Water management is a cornerstone of rangeland success, and requirements vary drastically between species. Cattle and horses typically require water on a daily basis to maintain health and productivity. Conversely, sheep and goats exhibit greater physiological resilience to water deprivation and can often go for approximately $2$ to $3\,\text{days}$ between watering cycles. However, animal production is consistently reduced when either the quality or the quantity of available water is low.

Environmental factors such as the salt content of rangeland forage also influence hydration needs. Incorporating high levels of salt into the diet leads to an increase in water intake. For example, sheep grazing on saltbush have been observed to require water $2\,\text{times per day}$. A similar trend was observed in cattle in New Mexico grazing on land where the water was high in total dissolved solids ($TDS$), resulting in a watering frequency of $2\,\text{times per day}$. Generally, sheep and goats possess a higher tolerance for salt compared to cattle, suggesting that cattle may require more frequent access to fresh water when salt levels in forage or water rise.

Economic and Social Considerations in Rangeland Management

The choice between livestock species involves weighing various economic advantages and labor requirements. Raising cattle is often preferred due to lower overall labor requirements and a relative reduction in predator problems when compared to sheep. Sheep, however, offer the economic advantage of producing two distinct commercial products: wool and meat. In environments dominated by oak vegetation, goats have been shown to yield higher economic returns. Research indicates that the highest economic returns overall are often achieved through a combination of cattle and wildlife management on the same rangeland.

Grazing Strategies and Breeding Efficiency

Common-use grazing—the practice of grazing multiple types of livestock on the same range—offers several benefits. This approach can substantially increase livestock production and promotes a better distribution of animals across the landscape. It ensures that a wider variety of available plant species are grazed, which improves the uniformity of rangeland use. Furthermore, it provides income diversification, reducing a rancher’s dependence on a single product. From a health perspective, common-use grazing reduces the risk of loss from poisonous plants and diseases.

In terms of reproductive management, a defined $65\text{-day}$ breeding season is advantageous for several reasons. It leads to increased weaning weights and results in a more uniform crop of calves. Furthermore, a shortened breeding season allows managers to more easily identify low-producing cows that fail to conceive within the designated window, allowing for more efficient culling and herd improvement.

Plant Toxicology and Livestock Health

Livestock poisoning by plants is a significant threat that requires proactive management. Nitrates are a common concern and can accumulate in a wide range of plants, including oat hay, alfalfa, barley, wheat, sorghum, corn, sudangrass, Johnsongrass, and beets. Weeds such as carelessweed, kochia, pigweed, Russian thistle, nightshade, bull thistle, Canadian thistle, sunflower, and bindweed are also known nitrate accumulators, as are vegetables like sugar beets, lettuce, cabbage, and potatoes. When consumed, nitrates found in plants like pigweed and lamb's-quarter disrupt the blood's ability to carry oxygen, leading to death via asphyxiation.

Other toxicological concerns include milkweed, which produces resins that affect the muscular and nervous tissues of livestock. While programs like those offered by the $USDA$ National Resource Conservation Service ($NRCS$) provide incentives to promote milkweed for monarch butterfly habitats, ranchers must exercise caution, as milkweed is toxic if overconsumed. Additionally, the consumption of large amounts of Mesquite can lead to a condition known as "wooden tongue" or a paralyzed tongue in livestock.

Range managers can prevent poisoning by ensuring animals are not placed on ranges with toxic plants after being deprived of forage or moved from dry feed. Maintaining a steady supply of salt is also vital, as salt-deprived animals may engage in pica or overconsume unfamiliar plants. In some cases, weed control may be necessary to physically remove poisonous species.

Wildlife Ecology and Habitat Heterogeneity

There is an increasing concern for wildlife on $US$ rangelands, driven by a growing human population with greater affluence and a higher demand for recreation. Society is also becoming more interested in how food production impacts the environment. Central to wildlife management is the concept of habitat heterogeneity, which is the existence of two or more different types of habitat within a specific area.

High heterogeneity is characterized by a mosaic of conditions, such as a pasture with some areas of short grass and low litter (due to heavy grazing) and other areas with tall grass and high litter. Low heterogeneity describes a uniform landscape where grass height and litter are consistent throughout. While managing for even plant cover is thought to maximize forage production for cattle, research suggests that managing for heterogeneity does not necessarily compromise cattle production. In the Great Plains, grazing is considered the practice with the greatest potential for managing heterogeneity. Other factors contributing to this diversity include fire and the activity of burrowing mammals.

Impacts of Rangeland Features and Grazing on Wildlife

Human-made features like shelterbelts can have mixed effects. While they provide cover for species like turkeys and deer, they are generally detrimental to native rangeland fauna. Trees serve as shelter for mammalian predators and perches for raptors, which can reduce the productivity of avian species and fragment their habitat. Conversely, the "edge effect"—the meeting point of two different habitats—is generally positive for wildlife populations, providing the diversity of vegetation required to meet various life-stage needs. Mule deer, for example, prefer habitats with high diversity over short distances.

Livestock grazing influences wildlife habitat both directly and indirectly. Direct impacts include the removal or trampling of vegetation used as food, the defoliation of food sources, and the overgrazing of riparian areas. Indirect impacts include changes in vegetation composition and a reduction in plant species diversity. While heavy grazing typically reduces calf and lamb crops and can lead to more similarities in the diets of various animals during drought, moderate grazing generally supports more diverse wildlife populations than heavy grazing or complete ungrazing. Notably, grasshoppers are more numerous on heavily grazed rangelands.

Small Mammals and Human-Wildlife Conflict

Small mammals like prairie dogs and jackrabbits are often viewed negatively by ranchers because they compete with livestock for forage. However, they provide significant positive impacts, including speeding up soil development, enhancing mineral cycling, and contributing to the formation of organic matter. To reduce competition between big game and livestock, managers should monitor the use of key plant species, identify alternative food sources, and ensure the rangelands contain key species for both groups. Additionally, legal protections exist for certain species, such as the Wild Free Roaming Horse and Burro Act of $1971$, which protects these animals on public lands in the United States.

Rangeland Improvement: Fire and Chemical Control

Prescribed burning is a vital tool with objectives including increasing livestock forage, reducing litter, improving wildlife habitat, and reducing fuel loads to prevent catastrophic wildfires. It can also reduce labor costs associated with handling horses and cattle. The three elements required for combustion are oxygen, fuel, and heat; heat is the element that can be manipulated by selecting specific weather conditions for the burn. Fire can affect the palatability of forage, as cattle tend to congregate on recent burns to eat tender new growth. However, burning can decrease available soil nutrients such as nitrogen, phosphorus, and sulfur, and the removal of cover can increase the visibility of sheep to predators. Additionally, the rate of fire spread increases as the steepness of a slope increases.

For chemical control of unwanted plants, foliar sprays are most effective when plants are growing vigorously and their leaves are fully expanded. Properly planned brush control can increase the capacity of the rangeland to support both livestock and wildlife simultaneously.

Questions & Discussion

Question 3: Identify three factors that affect animal selection with regard to rangelands.
Answer: Factors include topography, climate, type of vegetation, water requirements, predators, pests and diseases, and economic and social considerations.

Question 4: What type of animal is best suited for sloping, rocky terrain?
Answer: Goats and sheep.

Question 5: True or False: Sheep and goats need water daily whereas cattle and horses need water about every $2-3\,\text{days}$.
Answer: False. Cattle and horses need water daily, while sheep and goats need it every $2-3\,\text{days}$.

Question 6: How does salt content in rangeland forage influence the water requirements of livestock?
Answer: Higher salt content increases water intake. Sheep grazing saltbush need water $2\,\text{times per day}$. Cattle in New Mexico with high TDS drank $2\,\text{times per day}$. Sheep and goats have a higher salt tolerance than cattle.

Question 7: Discuss the economic and social considerations with regard to livestock and wildlife.
Answer: Cattle involve lower labor and fewer predator problems. Sheep produce meat and wool. Goats are profitable in oak-dominated areas. A combination of cattle and wildlife yields the highest economic returns.

Question 10: Identify four plants known to accumulate nitrates.
Answer: Sorghum, Johnsongrass, pigweed, and lamb's quarters. (Other include oat hay, alfalfa, barley, wheat, corn, sudangrass, beets, carelessweed, kochia, Russian thistle, nightshade, bull thistle, Canadian thistle, sunflower, bindweed, sugar beets, lettuce, cabbage, and potatoes).

Question 11: As a rancher, should you have concerns about the USDA NRCS milkweed program?
Answer: Yes, milkweed contains resins affecting muscular and nervous tissues and is toxic if overconsumed. However, it can supplement income if planted in areas not used for livestock.

Question 12: How can rangeland managers prevent livestock poisoning?
Answer: Do not put hungry animals on ranges with poisonous plants, provide plenty of salt, use weed control to remove plants, and select appropriate animal types.

Question 2 (Habitat): What is habitat heterogeneity? Provide examples.
Answer: Heterogeneity is the existence of two or more different types of habitat in an area. High heterogeneity involves a mix of grazed/short grass and ungrazed/tall grass areas. Low heterogeneity is uniform grass height/litter across the area.

Question 7 (Ranchers' Opinions): How did ranchers view prairie dogs in a $2016$ University of Nebraska survey?
Answer: Ranchers mostly viewed them negatively due to forage competition. Misperceptions include that they destroy all forage. Benefits include increased habitat diversity and improved soil conditions.

Question 8 (Bird Habitat Needs): Which habitats are ideal for specific wildlife?
Answer:

• Bare ground: Long-billed curlew, chestnut-collared longspur, horned lark, mountain plover, common nighthawk.
• Sparse vegetation: Long-billed curlew, chestnut-collared longspur, horned lark, mountain plover, common nighthawk, grasshopper sparrow, western meadowlark.
• Thick vegetation: Grasshopper sparrow, western meadowlark, lark sparrow, dickcissel.
• Shrubby: Lark sparrow, dickcissel, field sparrow, loggerhead shrike.

Question 4 (Combustion): What three elements are necessary for combustion in a prescribed rangeland burn?
Answer: Fuel, heat, and oxygen. Heat can be manipulated via weather conditions.