3. Adaptations of Animals to High Elevation Flashcards
Typical alpine environmental conditions from an animal perspective:
- Temperature – cold or hot, rapid changes, precipitation as snow all year
- Windy
- Long winters
- Steep and unstable slopes
- Generally low water and food availability
- Low oxygen – depends on elevation
Mountain Goats
- These incredible climbers are found in several of the large mountain ranges in north America
- Usually find them at the top third of the mountain living at the peaks and sheer rock faces.
- They live in family groups which helps them avoid predators thick insulated fur to keep them warm
- Body is large with short appendages to help with heat loss
- Very muscular legs to help run up steep cliffs
- Most notably, their Signature adaptation to deal with steep terrain is their feet
What adaptations do Mountain Goats have?
Specialized hooves
- Textured, rubbery pads that provide traction
- Cloven hooves that can spread apart and move independently
- Back of their feet have sharp dewclaws that keep them from slipping
Bighorn Sheep
- Another example of a well adapted mountain species similar to the mountain goat is the bighorn sheep
- These sheep are also found in various mountain ranges across north America however this species lives a little lower down on the mountain
- So they share many of the same adaptation as the mountain goat but a little less extreme
- They also live in groups for safety,
- They have thick fur, and are very agile on steep terrain
What adaptations do Bighorn Sheep have?
- Just like the mountain goat, they too have specially adapted hooves that allow them to stick to the side of the cliffs
- This is important because they need to be able not just to get around but also avoid predators
- They have their babies near the peaks of the mountains in the spring to keep them away from predators and once they babies get a little
- Older they start to come down, but even the babies are incredibly agile on the cliffs.
Alpine Ibex
Found in the European Alps
Summary of adaptations for mountain goats and bighorn sheep
- Specially adapted hooves – separated into halves
- Thick layer of coarse hair over their usual coat in the winter
- Familiarity with steep terrain and their territories
- Acute eyesight (~2 Km)
- Run at high speeds even on cliff faces (>30 Km/h)
- Travel in family groups to reduce risk of predation
- Specialized digestion allows them to get the most out of a poor diet:
Complex four compartment stomach allows them to obtain nutrients from forage
Eat a lot of forage rapidly and then retreat to a safe cliff to digest away from predators
Large teeth that grow throughout their life allows for grinding coarse grasses and grit
Wild Yaks
- Live high in the Himalayan mountains ~5500 m above sea level
- Have developed large lungs and a large heart to deal with low oxygen at altitude
- Thick fur coat, large body, short appendages, and specialized hooves etc.
-They are so well equipped to deal with the mountains and the elevation that people who live in the Himalayas have domesticated them and use them for transporting good and for food and milk
Strategies to cope with the cold
- Avoid the cold (Don’t let it get you!)
- Migrate
- Insulate: Burrows, Hair, Fat, Size, Physiology
- Deal with it (let yourself get cold!)
-Freeze
-Hibernate
Migrating across latitudes
- Alpine Swift
- Migrate south to avoid harsh conditions imposed by winter in the mountains
- Migrate distances of ~2000 km without stopping
- They forage and sleep while in flight
- This trip can take up to 6 months
Migrate across elevations
- Altitudinal bird migration involves annual seasonal movements up and down elevational gradients
- Of species wintering within USA & Canada ~30% engage in altitudinal migrations
- Higher elevation to lower elevation and back
- Several mammalian species also migrate across elevations
- This increasing their ability to find food and stay warm away from the extreme conditions on the mountain
Insulation
The other strategy for avoiding the cold is insulating
The umbrella term for many different behavioral strategies and physiological responses
Thermoregulation
Ability of the body to maintain its core internal temperature
Types of thermoregulation
- Physiological Mechanisms
- Neural responses (immediate): e.g. modification of blood flow to skin, sweating, shivering etc.
Acclimation responses (long-term): Changes in insulation, increased capacity for metabolic heat generation etc. - Behavioural Mechanisms
- Controlling body temperature by repositioning the body in the environment
Thermoregulation: Body temperature falls
Body vessels constrict so that heat is conserved. Sweat glands do not secret fluid. Shivering (involuntary contraction of muscles) generates heat, which warms the body
- Heat is retained
Thermoregulation: Body temperature rises
Body vessels dilate, resulting in heat loss to the environment. Sweat glands secrete fluid. as the fluid evaporates, heat is lost from the body
- Heat is lost to the environment
Decrease heat loss
Vasoconstriction
Piloerection
Countercurrent exchange
Vasocontriction
constricting blood vessels to limit flow and therefore limit cooling
Piloerection
Hairs stand up straight and puff out, which is known as piloerection but to us we call it goosebumps. It creates stagnant air above the skin blocking out wind and increasing warmth
Countercurrent Exchange
Arteries that send blood to the appendages and veins that bring blood back are close to each other in the body so they can exchange heat which prevents blood from cooling too much
Pika (“rock rabbit”)
Minimize exposure to extreme temperatures by burrowing
Snow provides thermal insulation from extreme temperatures
Subnivian space is critical for over-winter survival
Order Lagomorpha (Pika)
FAMILY OCHOTONIDAE
Ochotona: 30 Species
Only 2 in NA
FAMILY LEPORIDAE
Hares (Lepus): 32 Species
Rabbits: 29 Species
Do Pika’s hibernate?
No, they stay active all winter under the snow and rely on their cached food stores
Which animals hibernate?
Carnivores
1. Rodents
2. Insectivores
3. Monotremes
4. Marsupials
What are true hibernators?
True hibernators are smaller, drop temp. close to ambient, bouts last several days
What is winter lethargy?
(bears, carnivores) – temp drops a few degrees, bouts last weeks-months
Similarities between ‘True’ hibernators amd ‘Winter lethargy’?
In both, endothermy NOT abandoned – hibernators regulate temperature at lower level
Which animals are true hibernators?
Hoary Marmot (Exists throughout the western united states and Canada)
- Allow their core body temperature to drop to freezing
- Metabolism slows, heart rate slows to a few beats per minute, decreased neuron activity – brain dead!
- Awaken for a day every few weeks to eat, drink, pass waste
- Store food in their burrows
- Salty body fluids prevent tissues from freezing and crystalizing
What is the hibernation cycle?
Fall (Aug-Oct): Major fat-building (lipogenic) period-pack on as much fat as possible, prepare for Winter
Winter (Oct-Mar): Animals enter hibernation, drop Tb to near Ta, drop metabolic rate, start burning fat reserves
Spring (Mar-May): Arousal - males first, then females; mating, parturition, start replacing body mass lost
Summer (May-Aug): Continue feeding to build fat, sunning to help store fat, juveniles mature
Number of arousals __________ with shallower snowpack
increases
Do Brown Bears experience hibernation or winter lethargy?
Winter Lethargy
Brown Bear - Winter Lethargy
- Sleep for 5-7 months of the year
- Eat large amounts of food; gain up to 400 lbs to prepare for long sleep
- Create dens at high elevation on northern rocky slopes
- Do not pass waste the entire time or engage in any activities
- Body temperature drops slightly and metabolism slows slightly
- Recycle their waste to prevent muscle atrophy and other side effects (Urea is broken down into nitrogen to build protein)
- Easily wake up to disturbances
- Females give birth in the dens (exception to no activities)
Mountain Caribou
Special hooves
Main challenge is dealing with what?
Cold environments. A lot of species that are adapted to northern climates extend their ranges south in mountains
