The Golden-crowned Sparrow is a medium sized sparrow, slightly larger than the closely related White-crowned Sparrow. It has a distinct gold patch on its head, flanked by two dark black stripes. When not breeding, its plumage is more variable, ranging from a small, dull gold patch and no black, to near breeding season plumage.

The song is a three note whistle, descending in pitch. It is very distinctive and often described as “Oh, dear me”, each note an interval lower in pitch than the preceding. However, birds in the mountains of British Columbia have been reported to have trill on the third note, rather than a clear whistle as in other populations. These songs are heard mainly in the breeding season, but also in the wintering grounds just after fall migration as well as just before they take off for spring migration.

Alaskan gold miners along the trails called this bird Weary Willie, because of its call which sounded like “I’m so weary”. The song resembles the popular tune known as “Volare” (Italian for the infinitive form of the verb “to fly”) written by  Domenico Modugno in 1957. Sergio Franchi sang the song, with modified lyrics, as the television spokesman for the Plymouth Volare in the 1970s.

The entire population of Golden-crowned Sparrows migrates within North America. They leave the breeding grounds in Alaska and Canada late in the fall, most arriving on the wintering grounds throughout northwestern California, Oregon and Washington from mid-September through October. Birds begin to return to the breeding grounds in April or May.

These sparrows makes a habit out of digging in the ground for grubs, insects, and seeds. This is because it has extremely large feet and claws. They use a digging technique of jumping backward off of both feet at the same time, which stirs up the soil, leaf litter, or grass. They then move forward to see what they have uncovered. Sometimes, when they jump backward, you can see the seeds popping up from out of the grass, where they were hidden before. 

Golden-crowned Sparrow Nests are usually dug into the ground or placed in a depression so their rims are even with the ground. Each bird has its own feeding spot at a bird feeder. Even when there are no other birds around, it uses its spot exclusively. A group of Golden-crowned Sparrows are collectively known as a “reign” of sparrows.

The Golden-crowned Sparrow was considered a pest early in the 20th Century, because flocks would feed on vegetables and flowers in gardens and cultivated fields. Its actual impact was not as great as was originally thought, and it is no longer considered a pest. Its population has grown in the past 30 years, and the Golden-crowned Sparrow is now a more common Washington winter resident than it was 30-50 years ago. Its far northern breeding grounds are well protected, with many of them located in national parks, forests, and wildlife refuges.

The Pacific Tree Frog is a very common species of chorus frog, with a range from the West Coast of the United States to British Columbia in Canada. Living anywhere from sea level up to over 11,000 feet. They live in many types of habitats and reproduce in aquatic settings.

They can reach up to about 5 cm long from snout to urostyle. The males are often smaller than the females and have a dark patch of skin on their throat. This dark patch is the vocal sac which stretches out when a male is calling. These frogs can have highly variable color on their bodies. They can be anywhere from gray, brown, tan or bright green and can even change between them. They are usually a pale or white color on their bellies. They have many variations of markings on their back and sides that are usually dark and spotty. The one identifiable mark is a dark stripe that goes over the eye from the nose to the shoulder. Their skin is covered in small bumps. They have long legs compared to their bodies and they tend to be slender. Their toes are long and are only very slightly webbed. On the end of each toe, there is a round sticky pad that is used for climbing and sticking to surfaces.

The evolutionary history of these frogs is a very interesting one that has recently been changed to better suit tree frogs. Amphibians themselves are thought to have descended from the lobe finned bony fishes. These fishes had an ossified skeleton and emerged from the water as they developed limb girdles and terrestrial characteristics such as lungs and a neck. It is hard to figure out an exact frog lineage because of the lack of fossil record. The habitat in which these animals lived was moist and decay was quick, which was not helpful in preserving biological clues.

The genus appeared just after the dinosaurs went extinct. They originated in South America and expanded to the north into Mexico and eventually into North America. There was then a rise in sea level and the connection between the northern and southern populations was gone. They have been separate ever since and have become genetically distinct from one another.

One of the most interesting features of these frogs is their ability to change color from brown to green. Previously, it was thought that there were two different fixed colors that an adult tree frog could be. Now it has been found that some of them are actually able to change between the two. They can also change from lighter to darker. These color changing morphs are triggered not by color change in their environment, but a change in background brightness. This type of environmental change would be caused by seasonal fluctuation, and has been shown to be a very useful cryptic survival feature for these frogs.

Pacific tree frogs are most common on the pacific coast of California. They are also found eastward to Montana and Nevada. They love water, but they can also be found upland from ponds, streams, lakes. Their habitat consists of a wide variety of climate and vegetation from sea level to high altitudes. The tree frog makes its home in riparian habitat as well as woodlands, grassland, chaparral, pasture land, and urban areas including back yard ponds.

The Pacific Tree Frog begins mating in early winter to early spring. Since these frogs are so widespread geographically, it is thought that their breeding season is determined by local conditions. When it is time, the males migrate to the water. They all call at the same time very loudly. This lures the females to the water and they mate. The females lay their eggs in clumps of 10-90 and usually put them on and under vegetation and leaf litter in the pond. Females usually lay their eggs in shallow, calm water that has little action around it. If they are not eaten, embryos will hatch into tadpoles within one to three weeks.

The tadpoles feed on periphyton, filamentous algae, diatoms and pollen in and on the surface of the water. They feed using a beak like structure that helps scrape vegetation off surfaces and suction. Metamorphosis follows about two to two and a half months later. Prior to transformation, they stop feeding for a short time while their mouth is transformed from herbivorous to carnivorous. Then the tiny baby frogs emerge from the pond measuring as little as one centimetre. They hunt using their sticky pads to climb on vegetation and other surfaces. Much of their diet consists of spiders, beetles, flies, ants and other insects. They mature very quickly and are likely able to mate in the next season after metamorphosis. Predators include snakes, raccoons, herons, egrets, and other small mammals and reptiles. The tree frog is mostly nocturnal, but can be spotted during the day. It spends a lot of time hiding under rotten logs, rocks, long grasses and leaf litter.

These frogs are the most common frogs on the west coast of North America. Although the Pacific Tree Frog remains abundant and most populations of tree frogs appear healthy, there is some evidence of declines. The cause has not been fully understood, but pollution, the introduction of exotic species and habitat loss are very high on the list of factors. Some ways to stop amphibian declines are by respecting and protecting amphibian habitat as well as supporting laws and legislation that help to do this. Another important way is to help limit pollutants that will end up in amphibian habitat, usually from agriculture and urban run off, by boycotting companies who are heavy pesticide users and by not pouring chemicals or pollutants down storm drains or in amphibian habitat.

Helmholtz resonance is the phenomenon of air resonance in a cavity. The name comes from a device created in the 1850s by Hermann Helmholtz to show the height of the various tones. An example of Helmholtz resonance is the sound created when one blows across the top of an empty bottle.

When air is forced into a cavity, the pressure inside increases. Once the external force that forces the air into the cavity disappears, the higher-pressure air inside will flow out. However, this surge of air flowing out will tend to over-compensate, due to the inertia of the air in the neck, and the cavity will be left at a pressure slightly lower than the outside, causing air to be drawn back in. This process repeats with the magnitude of the pressure changes decreasing each time.

This effect is similar to that of a bungee jumper bouncing on the end of a bungee rope, or a mass attached to a spring. Air trapped in the chamber acts as a spring. Changes in the dimensions of the chamber adjust the properties of the spring. A larger chamber would make for a weaker spring, and vice versa.

The air in the the neck of the chamber is the mass. Since it is in motion, it possesses some momentum. A longer port would make for a larger mass, and vice versa. The diameter of the port is related to the mass of air and the volume of the chamber. A port that is too small in area for the chamber volume will choke the flow while one that is too large in area for the chamber volume tends to reduce the momentum of the air in the port.

Helmholtz resonance finds application in internal combustion engines, subwoofers and acoustics. In stringed instruments, such as the guitar and violin, the resonance curve of the instrument has the Helmholtz resonance as one of its peaks, along with other peaks coming from resonances of the vibration of the wood. An ocarina is essentially a Helmholtz resonator where the area of the neck can be easily varied to produce different tones. The West African djembe has a relatively small neck area, giving it a deep bass tone. The djembe may have been used in West African drumming as long as 3,000 years ago, making it much older than our knowledge of the physics involved.

Helmholtz resonators are used in architectural acoustics to reduce undesirable sounds such as standing waves by building a resonator tuned to the problem frequency, thereby eliminating it. This technique is most usually used for low frequency waves.