Heat Stress

Female Great-tailed Grackle, Quiscalus mexicanus coping with the 41°C day.

The behavior of various animal species changes as the season gets hotter. Birds pant, lift their wings away from their body, find shade, and appear more flush as vessels dilate to release heat. Many mammals also pant, lay flat in a cooler area, and expose the short-haired parts of their body. When the humidity is high, panting increases significantly. The evaporation of water from the lungs is not easily absorbed by the moist air.

The signs of heat stress in other animals are not unlike those of a person. An overheated animal may have heavy panting, glazed eyes, vomiting, unsteadiness, and a rapid pulse. When body temperature rises above 40°C (104°F) then it is considered heat stroke which can be life threatening. The mucus membranes become bright red, heart rate increases, vomiting and diarrhea may occur, and the lethargy and stupor may eventually become seizures and coma. For animals experiencing heat stress or early signs of heat stroke, it is important to use cool, not cold, water and a fan if possible. An animal with a late sign of heat stroke still needs cooling, but with the risk of damage to the liver, kidneys, and heart, a vet should be called.

Those who work with animals that live outside are trained to look for these symptoms, but it is also important for the pet owner to be aware. Always keep in mind that wild animals and many exhibit animals have acclimated to the climate as they have never lived indoors with air conditioning or heat. Prevention is best, providing the animal with adequate shade, water, and electrolytes if necessary. Those animals who haven't had time to acclimate to the heat should not remain outside for long.

Great Horned Owl

Great Horned Owl, Bubo virginianus

One of the most widespread and common owls in North America, and found throughout a great portion of South America, the Great Horned Owl is also one of the most recognized owl calls. The scientific name, Bubo virginianus, was gained from the first sighting in the Virginia colonies. The common name was obtained from the tufts of feathers that give a horn-like appearance. With a wingspan of just under 1.5m, and length at 0.5m, the great horned owl is an impressive size. Like many other raptors, the female is larger than the male. Their diet is broad, eating anything that moves and can be caught.

Fresh caught prey for the young to feed on.

Among the prey are invertebrates, mice, snakes, skunks, Virginian opossum, herons. Even other raptorial birds can call prey to the horned owl; including nestlings of ospreys and Mississippi kites, owls such as the screech owl, and falcons like the peregrine falcon. While the great horned owl usually hunt from a perch on a clearing edge, they have been observed to also walk on and turn over forest floor litter and wade in shallow water. The adult great horned owl has no natural predators although harassment by red-tailed hawks and crows especially are not uncommon. In retaliation, the owls often attack roosting groups of crows and kill many.

Nest in current use by mated Great Horned Owls.

The nests of the great horned owl are either previously built by other species, such as the red-tailed hawk and pileated woodpecker, or artificial when suitable natural nests are unavailable. The territory often does not change between seasons, but the nest will. Hostility and extreme aggression is common when young are still in the nest. After an incubation of close to a month, the young hatch by mid-February, roam the nest close to the beginning of April, and can fly decently by May.

Both parents equal help raise the young.

The weaning has the young in the nest for another few weeks before they finally leave the nest and territory by fall. The mated pair maintain their joint territory all year, but will only stay together during nesting season. The great horned owl may live close to 13 years in the wild, but in captivity may live closer to 40 years.

Anticipation

Feather from a Mockingbird, Mimus polyglottos

The photo for today will be a loose link to the post for Friday. The post on Friday I'm quite excited about as the subject of the photos (yes, more than one) is one of my absolute favorite captures. It is also one of the coolest things I've seen and it happened to be while visiting Colorado.

Rocky Mountain National Park

Rapid forming thunderstorm in the Rocky Mountains.

The extreme weather patterns of Rocky Mountain National Park are shaped by a number of factors including elevation, exposure, and slope. The highest precipitation in the mountains usually occurs during the summer and winter months. During winter, the high peaks and mountain ranges receive the majority of their precipitation as winds at the mountain top level are typically strongest. In summer, the sufficiently moist regional air masses are generated into thunderstorms with the help of the mountain peaks and ranges. This is quite evident during the end of July and most of August. It is not uncommon for these often rapid forming thunderstorms to become very severe within the eastern plains and slopes of Colorado.

Red Fox and Rabies

Red Fox, Vulpes vulpes

The red fox is a predator found not only in North America, but parts of Europe, Asia, and Africa as well as Australia after introduction to the continent for sport. From forests to grasslands, mountains to deserts, the red fox has adapted to a variety of habitats, but the most salient adaption is in suburban and urban areas. Their primary food source consists of small mammals and birds, but their flexible omnivore diet also means dining on fruits, vegetables, human garbage, pets, and pet food. Normally a shy, nocturnal hunter, the close contact with humans and pets can often cause issues as the fox is a high risk vector species of rabies. Although the source of rabies transmission in humans is vastly due to dog bites, these non-vaccinated domestic animals often acquire the disease from urbanized wildlife vector species such raccoons, skunks, and foxes. Many places worldwide have taken preventative measures against rabies in terrestrial mammals with a combination of vaccines and oral drops. These have been widely successful with places such as Ontario and parts of Germany declaring a rabies-free environment.

Bighorn Sheep

Rocky Mountain Bighorn Sheep, Ovis canadensis

The Rocky Mountain Bighorn Sheep are well adapted to their habitat with keen hearing, a highly developed sense of smell, and sharp eyesight to detect danger such as coyotes, mountain lions, and golden eagles if it is a lamb. Their specialized split hooves are soft and flexible inside with rough bottoms that aid in balance and grip. The horns of a male can weigh up to 14 kg (30 lbs) and are key in confrontations and fights for the right of mating. Clashes may last hours as their thick, bony skull helps prevent serious injury. Around the early part of the twentieth century, the population of bighorn sheep in Rocky Mountain National Park declined rapidly as settlers and hunters arrived. With the addition of disease introduced by domestic sheep and habitat alterations from ranchers, estimates put the population at near 150 bighorn by the middle of the century. This small population survived in isolated areas where range and human contact was very limited. Through the introduction of new herds, the native herds have grown and estimates currently put their number to 600 bighorn sheep within the park.

The missing patch of fur is likely an indication that this particular bighorn survived a brush with death only days earlier.

Mammatus Clouds

Mammatus cloud formation at the passing of a storm,

Characterized as rounded, sagging, pouch-like structures, mammatus clouds are a rare formation created by sinking air on the underside of cumulonimbus clouds. They are not, in fact, a sign of a tornado, but rather an indication that the worse of the weakening storm has passed.

The drooping structures are formed from precipitation particles occurring in high concentration due to momentum loss. The updraft that carries the precipitation enriched air loses that upward momentum causing the air to start spreading horizontally. The heavily saturated air sinks below the lighter surrounding air. Temperature increase as the subsiding air descends evaporating precipitation particles; however, more energy is required for evaporation than subsidence produces resulting in the sinking air being cooler than its surroundings.

Mammatus clouds will dissolve in time, but the lifespan depends on the contents. If the sinking air contains snow crystals or large drops of precipitation, greater energy for evaporation is needed resulting in long lived clouds.

More of my photos of this phenomenon can be found here showing the progression of formation.

Eastern Tiger Swallowtail

Eastern Tiger Swallowtail, Papilio glaucus

The Eastern Tiger Swallowtail, while an easily distinguished eastern butterfly, has a vast number of variations especially between genders. One particular dark phase of the female has a resemblance to the Pipevine Swallowtail though it lacks the poisonous quality. Depending on location, these butterflies may be seen flying anywhere between February and November, from Ontario down to Texas and no farther west than Colorado. Sources of nectar for this species include thistle, black-eyed susan, spicebush, honeysuckle, elm, and ironweed, and host plants include willow, elm, cherry, and poplar to name a few.

Pale Swallowtail

Pale Swallowtail, Papilio eurymedon

Primarily montane, the Pale Swallowtail is a common species of butterfly found flying anywhere between February and August, depending on location, in most of the western United States and parts of Canada. The wingspan of this species can reach 10 cm and is the only black-and-white swallowtail found in the western portion of the continent. While nectar plants may include blackberry, sweet-william, columbine, and thistle among others, their host plants include oceanspray, cherry, hawthorn, and buckbrush. The California Buckeye, Aesculus californica, in particular is noted as a favorite nectar source for Pale Swallowtails, and a classic example of the importance of native pollinators. The highly regarded European Honey Bee is a recent arrival and therefore unable to pollinate some native plants such as the buckeye as it is toxic to the bees.

Pipevine Swallowtail on Texas Thistle

Pipevine Swallowtail, Battus philenor on Texas Thistle, Cirsium texanum

The Pipevine Swallowtail is central to the mimicry of a number of butterflies including the Black Swallowtail and Red-spotted Purple due to its poisonous nature. As the name implies, the caterpillar Pipevine Swallowtail feeds on the Aristolochia family, the Pipevine family, collectively known for their poisonous leaves. After a number of feedings, the caterpillar, and soon butterfly, use those chemicals as defense, warning predators away. The single row of orange spots, lack of orange spot on the dorsal hindwing, and mostly dark forewing distinguish this species.

The adults feed on nectar like many other butterflies, including such flora as the Texas Thistle. This plant can grow anywhere from 2-5 feet, are drought tolerant, and are a great nectar source for butterflies and bees. The mature seeds provide an excellent food source for birds, and the seed fluff is often used for nest building. 

Rocky Mountain National Park

Sunset from the car along Trail Ridge Road.

My flight is a bit earlier than I realized so for today I'll just share another view of Rocky Mountain National Park. There will be no post on Friday, but updates will continue as normal again Monday.

Rocky Mountain National Park

Sunset along Trail Ridge Road, Rocky Mountain National Park

Encompassing over 1075 km² (415 mi²) with views cresting over to 3.5 km (12000 ft), Rocky Mountain National Park is a large and diverse place to visit. The environments range from montane meadows, to subalpine forests, up to alpine tundra. Black bears, bighorn sheep, marmots, and elk as just a few of the likely wildlife to be spotted in the area. The national park and surrounding areas provide a number of possible activities, from hiking and camping at one of the numerous sites within the park, to rafting and boating at nearby Estes Park.