Fossils

Fossil of a "bony fish" of the infraclass Teleostei

The word paleontology refers to the study of ancient life from the Greek words palaios (ancient) and logos (study). The word fossil comes from the Latin word fossilis (obtained by digging). Fossilisation occurs with the right circumstances: protection from scavengers and elements, and death in an optimal substrate such as sand, soil, mud, a river bed, or seabed. A sub-fossil is where decay, although slowed down, is still occurring and bone is still evident. A fossil is when chemicals and minerals percolate through the remains and recrystallizes it, or else erodes it leaving a hollow space. These remains that are dug up, from bones to teeth to skin, can be categorized by types. Trace fossils are evidence of animal behavior such as tracks, burrows, or coprolites. Mineralized fossils are when organic matter is replaced with minerals such as with bones, shells becoming pyrite or opal, or wood replaced with silica. An impression is when the creature decays but leaves an imprint in the sediment.

I was recently given a wonderful opportunity to photography, in detail, the newest fossil collection at the Heard Natural Science Museum and Wildlife Sanctuary. While the next number of post will be looking at some of these unique fossils, I will additionally be doing more detailed posts on Google+ if you'd like to see fossils that may or may not appear on this blog.

Brown Trout

Brown Trout, Salmo trutta

Brown trout are a non-native species first introduced in the United States in 1883 from Germany. These fish are relatives of Atlantic Salmon and popular with anglers which contributes to their purposeful stocking in a number of states. While brown trout have become well established in many areas, other place still periodically add more for the purpose of fishing. They are a very competitive species that often drive out natives. A brown trout will feed at night on other fish and invertebrates, and they can withstand environmental disturbances better than natives. A number of natives such as brook trout and Lahontan cutthroat have had severe population declines most likely due to brown trout populations.

Mimosa

Mimosa, Albizia julibrissin

Introduced from China, Mimosa, also called the Persian Silk Tree, can now be found throughout a large portion of the United States. The showy pink flowers which bloom from May to July make it a popular ornamental tree. Within Florida and Tennessee, it is considered an exotic pest plant. Although this plant tolerates moderate drought, most soil, and thrives in high summer heat, it is not winter hardy and much prefers watersheds. For these reasons, as well as other susceptibilities such as wilt and weak wood, mimosa has not become a highly invasive issue as of this moment. States where mimosa is becoming more an issue have encouraged alternatives to mimosa for planting such as redbud and flowering dogwood.

Gray Jay

Gray Jay, Perisoreus canadensis

The Gray Jay, although much more common in Canada and Alaska, can be found year round in patchy areas of the western United States. These birds have very thick plumage that envelopes the legs and feet when puffed, and feathers that cover its nostrils. They cache food during the summer to sustain through harsh winters. Their sticky saliva is used to glue small food items to branches above eventual snow lines. Gray jays have been observed making over 1,000 sticky caches within one day. This adaptation not only allows for survival during the winter far north, but makes late winter nesting possible.

Also known as Camp Robber, or Whiskey Jack.

Rather than attempt a second brood in the summer, they prepare for the winter and take advantage of all food sources possible. Omnivorous gray jays have been observed eating not only arthropods, berries, fungi, carrion, and eggs, but also baby bats and blood-filled ticks off other animals. These birds are well-known for their bold behavior, gaining nicknames such as "Camp Robber" and "Whiskey Jack" in their search for food.

Pygmy Nuthatch

Pygmy Nuthatch, Sitta pygmaea

The Pygmy Nuthatch is a songbird with preference for long-needled, open pine forests, especially older ponderosa pine forests. It is a small bird reaching only 9-11 cm (3.5-4.3 in), about a full 2 cm (1 in) smaller than other nuthatches. These birds are found year round in patchy ranges of the western North American continent. They eat insects and seeds, and will cache seeds all year, saving them by hammering the seed into crevices or under flakes of bark.

Unlike most other songbirds, the Pygmy Nuthatch breeds in large extended-family groups, and have nest helpers. These helpers, relatives and grown offspring, help defend the nest and feed the incubating females and chicks. Pygmy nuthatches do not roost alone, with one observation sighting 150 of these birds in a single roost hole. During the cold nights and after breeding season, these birds will huddle with other pygmy nuthatches in their tree cavity nest. The roost site changes to accommodate seasonal weather variations. A summer, breeding site generally has a larger entrance hole near branches, whereas a winter, non-breeding site will have a small hole, but larger space within to allow more birds inside.

Hummingbirds

♂ Broad-tailed Hummingbird, Selasphorus platycercus

Hummingbirds are known for their coloration which has earned them the nickname of flying jewels. Birds with colors such as red or yellow are due to pigmentation within the feathers. Those of blue are a result of selective scattering of light due to particles dispersed in the material of the feathers. Green coloration comes from a combination of pigmentation and light scattering, but iridescence, as seen in hummingbirds, comes from interference. As observed by Newton, thin film on the feathers of birds cause an interaction of light waves. This is why some species, such as the Broad-tailed Hummingbird, often look to have a black chin rather than the characteristic red expected depending on the viewing angle.

♀ Broad-tailed Hummingbird, Selasphorus platycercus

Hummingbirds are often associated with red flowers, but the associate of the two is not exclusive. The assumption that these birds prefer red has always been prevalent, but it does not hold up to experimentation. While a reasoning for a higher prevalence of red floral colors in hummingbird flora is seen, the reason has not been found. What has been discovered is hummingbirds visiting a vast variety of colored flowers, not just red flowers; however, there is a clear link between flower shape and hummingbirds. As expected with long bills, tubular flowers are properly associated with hummingbird. There has even been evidence of a link between sexual dimorphism in some hummingbird species and the flowers they visit. The bill differences in particular of male and female Purple-throated Carib Hummingbird of the Caribbean is a reversal of floral dimorphism of Heliconia plants, of which these birds are the sole pollinators. One species, Heliconia caribaea, is associated with the short, straight bills of males, while the species, Heliconia bihai, relates to the long, curved bills of females.

Hummingbird with a bird band on its leg.

The flying and hovering abilities of hummingbirds are well-known and studied. Although there are musculoskeletal differences between species within the family Trochilidae, the aerodynamic mechanisms hummingbirds employ are somewhat similar to those used by insects. As with other birds, the downstroke contributes the most to weight support, but upstroke plays an important role for hummingbirds in particular. The added creation of tip vortices from the wingbeats also helps to support the body weight of hummingbirds. While hovering is essential for hummingbirds, it proves an interesting issue with banding. Unlike most birds, if a hummingbird spots a mist net, it can stop midair before collision. A pull-string trap is often used to capture and band hummingbirds instead of mist nets. As expect, the bands themselves are incredibly small, varying in diameter to 0.3 mm up to 35 mm.

Hummingbirds

Broad-tailed Hummingbird, Selasphorus platycercus

Hummingbirds, nicknamed Flying Jewels, are found throughout the American continents from sea level up to an altitude of 5,000 m (16,500 ft). While most live in the tropics, they can also be found in habitats such as the mountains and plains. Within the Trochilidae family, there are 328 identified species of hummingbird. They consume not only nectar, but also a number of insects including mosquitoes, spiders, gnats, and aphids.

Hummingbirds are of the family Trochilidae.

With such a variation of habitats, many hummingbirds have evolved to adapt to those needs. Some hummingbirds, such as the Broad-tailed Hummingbird, enter a state of torpor during the cold nights to conserve energy. The Tooth-billed Hummingbird of Ecuador and Panama, as well as the Lucifer Hummingbird of the extreme southern United States and Central America, have bills to help with nectar robbing. While hummingbirds often serve as pollinators, reasons, such as competition with other creatures, may force adaptation to instead steal nectar.

Hummingbirds are extremely agile flies.

Many of these small eighth of an ounce birds are migrants travelling around 800 km (500 mi) a year. The Rufous Hummingbird travels 4,800 km (3,000 mi) from Mexico to Alaska. The Ruby-throated Hummingbird migrates at least 3,200 km (2,000 mi) from its wintering grounds as far south as Panama, to its breeding grounds as far north as Canada. This particular species is one of 16 species which breed in North America, and the only species that breeds in the eastern half of the continent.

Texas Brown Tarantula

Texas Brown Tarantula, Aphonopelma sp.

The tarantula of the family Theraphosidae is the heaviest spider by weight, but there have been no direct fatalities for this family of spiders. While containing sizable fangs, their main attack is through irritating, urticating hairs which are dislodged at the attacker. As they are easily kept in captivity, and are rather docile, tarantulas are becoming increasingly popular in the pet trade.

Eyes of the Texas Brown Tarantula

Texas brown tarantulas start migrating in late spring through mid-summer. During this time, males wander to find the females who stay in their den. Although they have eight eyes, they are all clustered together. Rather than be used to see distances, the eyes mainly help detect the difference between light and dark. Tarantulas are much more tactile using touch and chemical cues to move around. It is in part for this reason that, especially during migration, you may see many tarantulas, and they may not move out of the way.

My photo above was recently used alongside an intriguing story about a wayward tarantula in Nature in a New York Minute by Kelly Rypkema. I highly suggest you not only read the story, but explore the site as well for more information on wildlife in city of New York!

Relating to last week's post, hummingbird week has been postponed until next week!