Meteorological spring starts Sunday, and we are already starting to hear the calls of early migratory birds, heading north from southern wintering grounds, working to establish territory their among the best nesting sites available.
Red-winged blackbird, Agelaius phoeniceus, singing by Rhododendrites, May 2023
Some birds, including red-winged blackbirds, Agelaius phoeniceus, get their cue to start spring migration as temperatures get warmer. These species head to prairies, forests, and wetlands to claim a location they can protect, call for a mate, and establish a nesting site with good protection and food sources. Other birds, including many warbler species, return in spring when daylight hours lengthen. Generally flying at night, they use star positions and the Earth’s magnet field to guide them. If nights are stormy or heavily overcast, early morning may find hundreds of them waiting in fields for clear skies. Birds may also stop for a day or two in areas located on the southern shores of any large body of water to rest and feed before crossing.
Red-winged blackbird, Agelaius phoeniceus, flock at sunset by Jerry Segraves
North America flyway map by USFWS
Bird species around the world generally follow established flyways, established routes over specific locations between their southern and northern territories. Many migration routes do not follow a straight path. Some species have historical stopover or feeding locations that provide a rest point along the way. Other species may not be able to cross a mountain range; or a large body of water can act as a barrier for land birds, but may be a required food source for wetland birds.
Arctic tern, Sterna paradisaea, adult & juvenile by Charles J Sharp, Aug 2025
Arctic tern, Sterna paradisaea, in flight by Charles J Sharp, Aug 2025
Long distance migration routes are most common for birds wintering in subtropical and tropical areas and breeding in the northern hemisphere. Long migrations in the southern hemisphere are far less common because there is less land near the South Pole to support breeding activities. The record holder for migration distance is the Arctic tern, Sterna paradisaea, overwintering in Antarctica and breeding in Arctic locations, a round trip between 30,000 and 55,000 miles. Some shorter migrations are between upper and lower altitudes in mountainous regions.
Penguin migration map by Fred Cooke & Jenni Bruce, Aug 2011
Dusky grouse male, Dendragapus obscurus, displaying by US NPS
Most birds migrate in flocks, which reduces the energy needed to fly long distances and provides added protection against predators. Penguins migrate without flying. Most penguin species swim between locations, covering up to 1,000 miles round trip. A few species cover long distances on foot, including dusky grouse, Dendragapus obscurus, in the Rocky Mountains which walk from lower to higher elevations. However, a flock may encounter unfavorable weather or flying conditions that causes a large number of birds to stall in one location, introducing other risks including depleted food sources and predation by land-based animals.
At the Jurica-Suchy Nature Museum, we host a nature walk every other week to observe changes in our campus including the birds that are moving through the area. There are many birding groups worldwide that provide opportunities to observe and learn about migratory birds in every location. Consider joining a group, or take your own bird walk as we have clear days and warming temperatures and see who’s on the move in your area.
Polar bears, Ursus maritimus, live in the Arctic and are heavily dependent on the ice floes where they hunt, breed, and spend a majority of their lives, making them the only bear to be classified as a marine mammal. They are strong swimmers and are able to maintain a steady 6 mph swim speed for several hours, crossing long distances between ice floes. Polar bears are a relatively new species, having branched off from the brown bear family about 150,000 years ago. Their close family relationship enables them to breed with brown bears, and grizzly / polar bear cubs have been observed, although not often.
Polar bear, Ursus maritimus, walking on sea ice by vladsilver, Getty Images Pro
Polar bear, Ursus maritimus, swimming in Arctic Ocean by FrankHildebrand, Getty Images Signature
Many other marine animals inhabit the world of ice including the polar bear’s favorite prey: seals coming out of the water over the edge of an ice floe. Bears often wait at these locations for a chance to grab a seal with heavy, sharp claws. But seals are wary and slippery, and bears do not often capture them, losing 9 out of every 10 they hunt. Their white fur should help to conceal them against a background of snow and ice. But as you look at the following pictures, are they really white or yellow or tan or even green?
Polar bear in white by dagsjo, Getty Images Signature
Polar bear in yellow by ekvals, Getty Images Signature
Polar bear in green by Asten, Sep 2006
A polar bear’s fur has a top layer of guard hairs and a bottom layer called the undercoat. Guard hairs are much longer and completely cover the undercoat. Both hair types are transparent with no pigment of any color. The guard hairs are hollow tubes filled with air that scatter visible light into all the different wavelengths of the spectrum. When we see a structure scattering light, it appears to be white. However, polar bears rarely look completely white, except in the spring after their annual molt when they shed their old fur and grow a new coat.
Most of the time, polar bear coats are shades of yellow or tan, possibly with some darker colors. Oils rubbed off from their prey, including fat from seal and whale bodies, tinge the fur in shades of light yellow or tan. When they are on land, constant contact with dirt and other environmental elements may add darker colors to their fur. Polar bears work hard to keep their fur clean and in good condition. When combined with a thick layer of fat on the inside of their skin, it is the best insulation against the outside environment where they live. Clean fur also provides good camouflage when stalking prey. They may roll in snow or wash off in the ocean to clean their fur.
Rolling in the snow by webguzs, Getty Images
Bears that live in captivity, outside the Arctic, may display shades of green in their fur. Algae growing in warmer waters of captive environments gets inside the guard hair tubes, which make an ideal environment for it to grow. Neither saltwater nor extremely cold water, both found in Arctic environments, support the growth of algae. A long soak in saltwater is a popular restorative cure for bears in zoos.
Polar bear bathing at the zoo by iSailorr, Getty Images
Come to see our polar bear at the Jurica-Suchy Nature Museum to learn more fascinating facts about this iconic species. For information or to make a reservation, please click here: Visit JSNM
Sea turtles live in every ocean environment around the world, nesting on tropical and subtropical beaches, and migrating long distances. They spend their entire lives at sea except when females come ashore to lay their eggs. They have been on earth for over 100 million years, surviving the period when most dinosaurs and other reptiles died out 65 million years ago.
Coral reef & hawksbill sea turtle by jakubgojda, Indian Ocean, Maldives
Sea turtles are large, air-breathing reptiles with upper (carapace) and lower (plastron) shells. Six of the seven species are covered by hard scales called scutes. Although none have teeth, jaws are suited to each species specific diet. Sea turtles do not have ears, but there are eardrum openings covered by a flap of skin. Their sense of smell is excellent as is their underwater vision, although they are nearsighted when out of the water. Along with a streamlined body, they possess powerful legs and claws for swimming, diving, and catching food.
Green turtle eating seagrass by LauraDin, Getty Images
Green sea turtles, Chelonia mydas, on coral reef by Artush, Alam, Egypt
Sea turtles, along with manatees, are excellent caretakers of seagrass beds and coral reefs, habitats that are vital to the reproduction of fish, shellfish, and crustaceans. Seagrass, one of their favorite foods, grows faster and stronger with daily trimming from turtle munching. Coral beds, vulnerable to collapse and suffocation under mass quantities of sponges and small crustaceans, benefit from sea turtles that eat several hundred of these animals each day.
Olive ridley digging egg chamber by JHVEPhoto, Getty Images, Costa Rica
Green sea turtle hatchlings by Penny Britt, Getty Images
After reaching sexual maturity, which takes from 15 to 50 years, depending on the species, female sea turtles return every two to five years to the beach where they were born to lay their eggs. On average, they dig three to seven nests and place about 100 eggs in each. Baby sea turtles break out of their egg and instinctively flee for the lighter colored horizon where the ocean meets the beach. They spend several years in the open ocean feeding and growing before venturing into shallower waters to eat, mate, and reproduce. Only about one in a thousand babies will grow to be an adult. Most are prey for birds, crabs and fish, but many are killed by humans for food, medicines, and religious ceremonies. Nesting site habitat destruction and turtles caught as part of the fishing industry also play a part in population decline.
Jellyfish & jacks by melissaf84, Getty Images, Coral Sea; Whelks by Pack-Shot, Getty Images; Reef crab by JohnAndersonPhoto, Getty Images, Lembeh Strait, Indonesia; Posidonia seagrass meadow by Arnaud Abadie, Getty Images Signature, Mediterranean Sea
Females lay all of their eggs on land, but nesting sites and the best feeding sites may be thousands of miles apart. Sea turtles are found throughout the world’s oceans following concentrations of jellyfish, sponges, and crustaceans found in coral reefs and seagrass beds. Leatherback females have been tracked making migrations of over 12,000 miles between nest sites and the best annual feeding grounds during non-breeding seasons.
Read facts on each species in the sidebar, shown below. Come to the Jurica-Suchy Nature Museum where we have loggerhead, hawksbill, and green sea turtles on display to learn more about these creatures and their hidden realms.
Pics 1&2: Green sea turtle, Chelonia mydas, by DonArnold, JSNM 2023; Pics 3-6: Hawksbill sea turtle, Eretmochelys imbricata, by DonArnold, JSNM 2023; Pic 7: Loggerhead sea turtle, Caretta caretta, by DonArnold, JSNM 2023
Sea turtle species…
There are seven species of sea turtles in the world. All are experiencing dwindling populations from various threats. Two are critically endangered: the hawksbill sea turtle and the Kemp’s ridley sea turtle. Two are endangered: the green sea turtle and the flatback sea turtle. Three are listed as threatened: the leatherback sea turtle, the olive ridley sea turtle, and the loggerhead sea turtle.
Hawksbill sea turtles, Eretmochelys imbricata, have a narrow head allowing access to tight spaces in coral reefs, the usual spot to find sponges. They consume 1,000 pounds of sponges annually, keeping coral reefs free from suffocation by the sponges. These turtles are medium size at 2′-3′ and 100-200 pounds. Females nest on beaches among rocky areas 3-4 times in a season and lay 140-200 eggs in each nest.
Hawksbill portrait, Eretmochelys imbricata, by Sheraca, Dec 2014; Hawksbill sea turtle, Eretmochelys imbricata, by Goug Finney, Sep 2019
Kemp’s ridley sea turtles, Lepidochelys kempii, are the smallest species at 2′ in diameter and 75-100 pounds. Kemp’s ridley turtles have made a huge recovery from the 1960s, when there were about 200 individuals left, to almost 9,000 today. This is due to changes in Mexico’s laws, where 95% of their nesting takes place, to protect nest sites from disturbance.
Kemp’s ridley sea turtle, Lepidochelys kempii, by USFWS, Sep 2010
Green sea turtles, Chelonia mydas, grow to 4′ and 500 pounds. They are herbivores with a finely serrated beak for biting seagrass and scraping algae from hard surfaces. This is the only species known to come onshore to bask in the sun. They are named for the color of their fat, not their shell.
Green sea turtle, Chelonia mydas, by Florida Fish&Wildlife
Flatback sea turtles, Natator depressus, have a flattened carapace, unlike other turtles. They are medium sized at 3′ and 200 pounds. Found only in Australia, they do not migrate. Females lay only about 50 eggs in a nest, but nests are well spread out, helping to better protect their eggs. Their biggest threat is being preyed upon by saltwater crocodiles.
Leatherback sea turtles, Dermochelys coriacea, are the largest species at 4′-8′ and 500-2,000 pounds. They consume mostly jellyfish, daily eating their own weight in food. They have no scutes, but are covered by a flexible, leathery skin that allows them to dive up to 4,000 feet deep searching for prey. These turtles have thermoregulatory adaptations that allow them to hunt in very cold waters from Alaska to Chile, and they regularly make the longest migration of any vertebrate animal, traveling over 12,000 miles annually.
Leatherback sea turtle, Dermochelys coriacea, by Claudia Lombard, USFWS, Jun 2011
Olive ridley sea turtles, Lepidochelys olivacea, are small at 2′ and 75-100 pounds. They are the most abundant of all species. On certain beach sites, nesting females form an arribada, a grouping of all the females offshore who all come ashore at the same time to nest and lay eggs. Females on other sites may nest alone. Arribadas are particularly vulnerable to mass mortality events, but these are rare and population numbers remain consistent.
Olive ridley sea turtle, Lepidochelys olivacea, by Charles Peterson, Head Start Programs, Oct 2002
Loggerhead sea turtles, Caretta caretta, grow to 4′ and 200-400 pounds. Their very large heads and jaws can easily crush hard shells, allowing them to eat crabs, conches, and whelks. They have the largest concentration of nests annually, including 30,000 at a single Mediterranean location. Their shells provide space for 50 to 100 epibionts: plants and invertebrates that live permanently attached to their shells.
Loggerhead sea turtle, Caretta caretta, & epibionts by actor212, Aug 2017
