nesting – Discover-Nature

Squirrels of Illinois

Squirrels are members of the family Rodentia, along with about 40% of all mammals species including mice, rats, voles, beavers, muskrats, guinea pigs, and hamsters. Rodents are characterized by the two front teeth on both the upper and lower jaws that grow continuously their entire lives.

^{Note incisors on left strike against each other to remain sharp; Molars grow in back of mouth}

^{Rodent dental system by V. Leche, professor Stockholm hogskola}

^{Guinea pig incisors by Morbakka, Oct 2024}

Squirrels in Illinois can be found in forested areas as well as urban communities. They all use their long tails for balance when climbing trees or resting on branches as well as running along branches, wires, and tops of walls. Squirrels are excellent climbers and can jump up to ten feet. They are able to gnaw and chew through almost any non-metal material.

^{Grey squirrel jumping to a fence top by AJ, Nov 2017}

Most species are solitary dwellers, but not territorial, able to live on their own, but in close association with other squirrels, rarely fighting for territory, food, or mates. They breed twice each year, once in winter and once in early summer. Two to four young are typically born and can fend for themselves after about two months. The young will often stay with the mother until the next litter is born.

Squirrels use tree cavities for raising young and for protection from predators, but most of the time they live in nests built of twigs and leaves high up in a tree. Nests are normally located near readily available water. They eat a variety of foods including nuts, berries, acorns, fruit, buds, fungi, seeds, and insects.

^{Fox squirrel by Corey Seeman, Jan 2023}

^{Fox squirrel by Corey Seeman, Jan 2020}

The fox squirrel, Sciurus niger, is the largest species in Illinois at about 22″ in length and weighing up to two pounds. Their fur is reddish-brown, with lighter shades on ears, bellies, and tail edges. They are common in urban areas, but are often found where there are no gray squirrels. Fox squirrels are most active in the early morning and late evening and are excellent swimmers.

^{Grey squirrel by Zoblinski,}
^{Getty Images}

^{Leucistic (white) grey squirrel}
^{by Pete Weiler, Pexels}

^{Melinistic (black) grey squirrel}
^{by Tom GV, Getty Images}

The Eastern gray squirrel, Sciurus carolinensis, is slightly smaller at about 18″ long and weighs about a pound. They have short, gray fur, but are often subject to genetic variations that result in different colored fur. Common variants in Illinois include melanistic or black squirrels, leucistic or white squirrels, and albino squirrels. Eastern gray squirrels are abundant in urban areas and large forested tracks. However, there are very few forests left in Illinois to support these animals.

^{Red squirrel by Christopher Defalco, Pexels}

Red squirrels, Tamiasciurus hudsonicus, are small, about a foot long, weighing about a half pound. They have reddish-brown backs with white bellies and a dark orange stripe down their back in summertime. Red squirrels are found only in the northeast quarter of the state in large forested areas. They are diurnal, active in early morning and late evening.

^{Southern flying squirrel by EEI_Tony, Getty Images}

The Southern flying squirrel, Glaucomys volans, is the smallest species at about nine inches, weighing only two ounces. They have gray-red-brown backs with white bellies and are nocturnal, making them difficult to observe. Flying squirrels have large eyes to see better at night and a long, flattened tail that is used as a rudder when airborne. A flap of skin runs between the front and back legs on either side of their body and is stretched taut when their legs are spread, providing the ability to jump from a high place and glide down to a lower place. Unlike other squirrel species, flying squirrels share a communal nest during most of the year.

^{Northern flying squirrel by Dopeyden, Getty Images______While this is not the species found in Illinois, flight patterns are very similar…}

Squirrels play an important part in forest and urban tree regeneration. They bury acorns and other nuts in warmer months for winter food stores, but usually bury many more than they actually consume. The remainder are left to germinate, resulting in many new trees each year. Squirrels are fun to observe and can provide enjoyment and an opportunity to learn about wildlife behaviors. Come down to the Jurica-Suchy Nature Museum or a nature center near you to learn more about these amazing animals.

Great Horned Owls

The great-horned owl, Bubo virginianus, is native to much of the Americas, including most of North America and Central America and about half of South America. It is the second heaviest owl in North America, right behind the snowy owl, Bubo scandiacus, weighing up to five-and-a-half pounds with a wingspan between three and five feet.

^{Great-horned owl, Bubo virginianus, by Andy Reago&Chrissy McClareen, Aug 2012}

^{Range and distribution of Great-Horned Owl, Bubo virginianus by BirdLife International, 2014}

Feathers cover the entire body, including their feet, and are varying shades of browns and grays. Their backs and heads are mottled or barred in several patches. This coloration, especially when coupled with mostly nocturnal activities, provides excellent camouflage. Their ‘horns’ are actually feathers sticking upwards on either side of their heads. These are called plumicorns, but their function is not well understood. The feather structure of the wing allows owls to fly silently and includes a serrated leading edge to disrupt turbulence and softer feathers behind to help deaden sound.

^{Great horned owl plumicorns by Jean-pol Grandmont, Aug 2013}

^{Great horned owl wing structure by Peter K. Burian, Aug 2015}

The owl’s ears are covered by feathers, but are not symmetrical with one being higher on the side of the head than the other. This arrangement provides the owl with the ability to triangulate sounds and precisely locate prey in the dark or when prey is hidden, such as when an animal is moving about under a layer of snow. Their flattened face, shaped as a round disc, also helps to direct sound to their ears. Like all owls, their eyes are fixed in the sockets, but the bird can swivel its head almost 180° to either side allowing it to see in all directions.

^{Great horned owl talons by Curtis Bouvier, May 2010}

Great horned owls hunt from a perch, observing the area below them before diving swiftly and silently from far above. Their diet consists of small mammals, birds, amphibians, and a variety of snakes. Their talons are powerful and deadly, with a grip comparable to much larger birds such as golden eagles. Most prey is killed by being pierced or crushed in the talons. Owls may hunt and kill for more than their immediate needs and will cache their kills for future meals.

Great horned owls are not migratory. When an owl is ready to mate, courtship occurs in late fall and pairs mate for life, establishing a territory together in which they will live their entire lives. Most territorial defense is through hooting at a transgressor, but rare physical confrontations have been observed. If an owl cannot establish its own territory, it will live in silence among the fringes of other territories.

^{Great-horned owl juveniles, Bubo virginianus, by Alan Vernon, Jun 2010}

^{Great horned owl female & juvenile on nest by John Kees, Apr 2012}

Males are responsible for picking a nest site, almost always taking over a nest constructed by another species. Mated pairs breed once every two to three years, laying from one to six eggs. Egg laying occurs between late February and early April. The female alone incubates the eggs, never leaving the nest, while the male hunts and brings her food. After about 33 days, the eggs hatch. Young owls will start to fly after seven weeks, but take a full month or more to become proficient.

^{Great horned owl calling, Bubo virginianus, by Michael & Katie LaTour, Jan 2019 (at 0:02, 0:10)}

^{Great-horned owl pair calling by Bushman, Dec 2013 (at 0:18, 0:41, 0:51, 1:22)}

Owls are more often heard than seen. Although the females are larger than males, females have a smaller voice box and thus a higher pitched hooting call ending with a slight rising note. Juveniles can make hissing or screeching sounds and are often misidentified as barn owls, Tyto furcata.

You can learn more about these magnificent birds at the Jurica-Suchy Nature Museum. Make a reservation to come see us by visiting our website at: https://ben.edu/campus-links/jurica-suchy-nature-museum/ (click on Register to Visit the Museum).

Ostrich

The ostrich, the largest and heaviest bird, is one of the handful of birds that cannot fly. They live in arid and semi-arid habitats in Africa, as well as in a small population of once captive birds that were released into the wilds of Australia. Several sub-species of the common ostrich, Struthio camelus can be found across most of Africa, while the Somali ostrich, Struthio molybdophanes, is only found in the far east around the Horn of Africa.

^{Common ostrich, Struthio cameus, Tanzania by Patrick Gijsbers, Getty Images Signature; Female Somali ostrich, Struthio molybdophanes, in Kenya by Ninara, Dec 2013; Male Somali ostrich, Struthio molybdophanes, in Kenya by Christiaan Kooyman, Jan 2003}

Ostrich males, called roosters, are predominantly black and can grow to 9′ and 180 pounds, while the slightly smaller females, called hens, have grayish-brown feathers and top out at about 6′ and 240 pounds. They live 30-40 years in the wild. Ostrich eyes, at almost 2″ in diameter, are the largest eyes of any land animal. Their species, camelus, refers to their long necks, large eyelashes, long legs, and their ability to go without water for extended periods.

Birds that can fly have many strong flight muscles attached to their sternum, which is shaped like a keel, an elongated structure which is narrow at the top and flares out at the bottom. However, the sternum of the ostrich is flattened and their wings are quite small. They do have powerful legs that allow them to sprint over 40mph and run long distances at an average speed of 31mph. Their long legs can cover 10-16 feet in a single stride. They only have two toes with one having a long claw that can dig into the ground for extra traction.

Notice the flattened sternum on the lower right of the ostrich compared to a flying bird below with a much larger bone.

^{Above: Flying bird shows large keel for flight muscles by LeeLiyi, Jun 2006}

^{Left: Ostrich skeleton, Museum of Veterinary Anatomy, FMVZ USP Wagner Souza e Silva, Dec, 2015}

Ostriches live in small family groups called herds. An average herd is about a dozen birds, led by one dominant male and one dominant female, called pack leaders. When males are ready to breed, they make a booming sound using an air sac in their throats that can be heard over long distances. When a female approaches, the male will puff out his chest, bow to the female, and do a dance that includes much tail shaking. This is repeated several times until the female indicates whether or not she will mate.

Ostrich eggs in shallow sandy depression, Namibia, by Th Trede, Getty Images

A dominant male digs a shallow nest 9 to 10 feet wide and mates with several females. Each mating results in 7-10 eggs laid together in the one nest. Ostrich eggs are the largest of any egg in the world weighing about 3 pounds, equal to 2 dozen chicken eggs. One male and one female will take turns incubating about 20 of the eggs, while the remaining eggs are ejected from the nest. Babies hatch in six weeks and are the size of a chicken when born, but they will grow about a foot a month, reaching adult size in six months.

Ostrich toes & claws by Mirko Vuckovic, Getty Images

Ostriches are omnivores mainly eating roots, seeds, and leaves, but will also eat insects, rodents, and snakes. They lack teeth; and as with many birds, they ingest small pebbles to help grind their food in the stomach. They are most vulnerable when eating or protecting their nests, and predators include lions, cheetahs, hyenas, and jackals. When threatened, an ostrich will not bury its heads in the sand. The bird may lie down on the ground with its head and neck stretched out to present a lower profile. They may run away, but if that is not possible, especially when protecting a nest, they will stand their ground. Their legs and sharp claws are powerful enough to deliver a kick capable of killing an adult lion. Many predators will not attack an adult ostrich, but their eggs are a delicacy for predators, vultures and other opportunists.

Many farms raise these birds, harvesting feathers and leather for clothing, plus meat and eggs for food. Although they are not considered endangered, ostriches are still threatened by habitat loss and poaching. At the Jurica-Suchy Nature Museum you can view an adult ostrich, nest and eggs, plus see our new display on the skeletal structure of birds including our adult ostrich skeleton.

Hummingbirds

It is getting to the end of summer, and many bird species that winter in Central and South America will soon be starting their migrations. Of the 320 species of hummingbirds, 15 spend the summer breeding in North America, from the Gulf Coast states to southern Canada, before returning to winter habitat farther south. Only one species, the Ruby-Throated Hummingbird, Archilochus colubris, breeds east of the Mississippi River.

7 of the 15 hummers that breed in North America:
- Anna’s Hummingbird, Calypte anna, by Alan Scmierer-USFWS, Mar 2007
- Black-chinned Hummingbird, Archilobus alexandri, by Paul Crook-USFWS, Jun 2024
- Blue-throated Hummingbird, Lampornis clemenciae, by Alan Schmierer-USFWS, Jun 2024
- Broad-billed Hummingbird, Cynanthus latirostris, by Alan Scmierer-USFWS, Mar 2022
- Buff-bellied Hummingbird, Amazilia yucatanensis, by Alan Scmierer-USFWS, Jan 2010
- Broad-Tailed Hummingbird, Selasphorus platycercus, by Tom Koerner-USFWS, Feb 2024
- Allen’s Hummingbird, Selasphorus sasin, by Wendy Miller-USFWS, Jun 2024

Hummingbirds have a very high metabolism with a normal heart rate of 250 beats per minute that accelerates to almost 1250 beats per minute when in flight. They consume large amounts of nectar each day to get enough sugar to support their energy requirements. Several small grooves running the length of their tongue funnel nectar into their throat by capillary action, a force that causes liquid to rise in a small tube without needing to use air to suck the liquid in. They also eat any small invertebrate to fulfill protein, vitamin, and mineral needs. Hummingbirds snatch insects mid-air while in flight, poach them from spider webs, and glean tiny moth caterpillars from new leaves and branch tips. Another foraging method uses the blast of air beneath their powerful wings to roll over leaves on the forest floor, revealing the insect life below.

^{Anna’s hummingbird catching insects by Stan Lupo, Jul 2023}

Hummingbirds do not bond with a mate. Females establish a territory that optimizes the available nectar and offers multiple nest sites. Males establish a territory based on encountering as many females as possible. Both will defend their areas from other hummingbirds, as well as other nectar feeders including butterflies and bees. Daily feeding starts on the outer edge of their territory to chase out any overnight interlopers and ends with nectar sources deep inside the area’s interior. Males will breed with as many females as possible. Females may have more than one brood of eggs each year, either concurrently or one brood following another.

Nests are about 2″ in diameter, built of small twigs, lined with soft plant material, and covered on the outside with greenish-gray lichens. Nests are bound to branches with spider silk, usually in a forest clearing. The lichens provide camouflage by making the nest appear as a large knot when seen from below. Females reach breeding age at the end of their first year, and can breed throughout their lifetimes. They construct one or more nests, each containing two white eggs, the size of peas, which are incubated by only the female for 14 to 16 days. The male takes no part in raising the young birds, coming together with the female only during mating.

^{Allen’s Hummingbird nest, by Mike’s Birds, Mar 2013}

^{Ruby-throated hummingbird on nest with lichen, by Lorie Shaull, Jul 2020}

Hummingbirds found in the western portions of North America travel overland migration routes. However, midwestern and eastern birds fly non-stop over the Gulf Of Mexico. A hummingbird can increase its fat reserves and double its body weight in the 7 to 10 days prior to the overseas trip. Through studies using banded birds, we have learned that they fly alone, normally at night, along with large flocks of other birds. Young birds, making the trip for the first time, can successfully navigate the migration route with no prior training. Their guidance system, how it works, and how it is learned are all still a mystery.

No hummingbird species are listed as endangered. However, hybridization among species is common, and their small size and great speed make them very difficult to count and track. Little data is available about population size changes and movements; however, more birds have been found over-wintering as far north as the Gulf Coast states of North America.

At the Jurica-Suchy Nature Museum, we have numerous bird specimens on display, including hummingbirds. We welcome you to come in and learn more about these amazing creatures.

Remaining 8 species that breed in North America:
Calliope Hummingbird, Selasphorus calliope, by Barbara Wheeler-USFWS, Nov 2021
Costa’s Hummingbird, Calypte costae, by Wendy Miller-USFWS, May 2020
Rivoli’s Hummingbird, Eugenes fulgens by Doug Greenberg-USFWS, Aug 2017
Lucifer Hummingbird, Calothorax lucifer, by Jim Gain-USFWS, Mar 2022
Ruby-throated Hummingbird, Archilobus colubris, by Alan Scmierer-USFWS, Jun 2024
Rufous Hummingbird, Selasphorus rufus, USFWS, Jun 2024
Violet-crowned Hummingbird, Amazilia violiceps, by budgora, Mar 2014
White-eared Hummingbird, Basilinna leucotis, by Alan Scmierer-USFWS, Mar 2022

Sea Turtles

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}

Puffins

Puffins are part of the Alcidae family of seabirds along with murres, guillemots, auklets, murrelets, and 25 recently extinct species. All members of the family can fly and are excellent divers and swimmers. Three species are found in the North Pacific Ocean including the tufted puffin, Fratercula cirrhata, horned puffin, Fratercula corniculata, and rhinoceros auklet, cerorhinca monocerata. The Atlantic puffin, Fratercula arctica, is the only species found in the North Atlantic Ocean.

^{Images clockwise: Atlantic puffin, Fratercula arctica, portrait by stockomotion, Getty Images Signature; Horned puffin, Fratercula corniculata, showing horns over eye by webguzs, Getty Images; Tufted puffin, Fratercula cirrhata, on the water by Bruce Block, Getty Images Signature; Rhinoceros auklet, Cerorhinca monocerata, by nikkigensert, Getty Images}

The rhinoceros auklet was thought to have been misidentified when it was first discovered and named. However, DNA testing has shown that all four puffin species have a common auklet ancestor. Puffin species have short, stocky wings and tails, with darker gray-to-black plumage on top of their heads and backs and lighter whitish-to-brown plumage on their faces and underparts. Their bills change color during breeding seasons to display several stripes of red, orange, yellow, and black.

Tufted puffin, *Fratercula cirrhata*, breeding coloration by MrDaz, Getty Images Signature

Short wings require the birds to beat them quite fast to fly, about 400 beats a minute, but they achieve speeds of 45 to 55 mph in flight. Short wings are used as powerful flippers underwater along with feet used as rudders. Puffins can dive to 200 feet or more catching a dozen or more small fish and invertebrates as they swim through the water. A uniquely designed hinge on their bill allows the top and bottom bill to meet at several different angles so the bird can add more fish without losing its grip on any that are already caught.

^{Images clockwise: Horned puffin, Fratercula corniculata, with fish catch in Alaska by Gerald Corsi, Getty Images; Atlantic puffin, Fratercula arctica, with catch by Daniel Jara, Getty Images; Rhinoceros auklet, Cerorhinca monocerata, with seven fish Andrew Reding, Jul 2010}

Puffins spend winters at sea, far from land, floating on the surface or pursuing prey. Breeding season occurs in late spring, and most adult birds come together, forming large colonies containing breeding and non-breeding individuals. Non-breeding birds spend hours each day exhibiting a behavior called wheeling flight – flying figure eights over the cliffs where the colony is located. After finding a mate, puffins form long-term pair bonds. After breeding, pairs may split up when out at sea, but often return the next breeding season to find the same mate and nesting site. Puffins breed in large colonies on coastal cliffs of offshore islands. Only one egg is laid and both parents incubate the egg and feed the chick. Chicks fledge at night, and juveniles spend the first five years out at sea before returning to the breeding colonies.

^{Horned puffin, Fratercula corniculata, nesting on Latrabjarg Cape, Vestfirdir, Iceland by Nikolay Tsuguliev, Getty Images}

^{Atlantic puffin roost by Shankar S., May 2016}

Puffins are not considered endangered, but are starting to encounter trends affecting the continuity of their successful breeding. Warming waters in the oceans are reducing populations of fish that breed and live in cold water areas, that are the favorite prey of the auk family. Threats on the mainland of Iceland, historically one of the largest breeding colonies, include being hunted by mink introduced in the 1930s, so most colonies are now located on offshore islands. Hunting for feathers, eggs, and meat has been sustainable on island ranges for hundreds of years. However, hunting on the American mainland during the late 1800s and early 1900s eradicated the population at one point. In the last 50 years, about 50,000 birds have returned to protected areas in Maine. Their biggest natural predator is the great black-backed gull which dive-bombs and picks off birds near shore during breeding periods.

^{Tufted puffin, Fratercula cirrhata, spreading its wings by TiannaChantal, Getty Images}

Puffins have an average lifespan of over thirty years, spending most of their lives out at sea. Reproduction rates are low with only one chick born each year to a pair of puffins, but a breeding pair may produce twenty chicks in their lifetimes and threats from natural predators are small. Puffins are favorite species in many zoos and some aquariums. Learn more by visiting a local institution or take a virtual tour from a live webcam at: https://explore.org/livecams/puffins/puffin-loafing-ledge-cam.

Bird Eggs

It is spring in the northern hemisphere, and many birds are claiming territories, finding mates, and establishing nesting sites. Raising new families will take most of the summer and early autumn. As we watch birds who have laid their eggs, it may seem that not much happens until the young hatch, but there is lots of activity taking place.

^{RWBB calling by mirceax from Getty Images}

An ovum, the female reproductive cell, starts its journey to become an egg in the oviduct where it is fertilized by stored sperm from a male and encased in a glob of protein-filled gelatin to form a yolk. Additional proteins, known as the albumin or egg white, are added to nourish the embryo as it grows inside the egg. Calcium carbonate, a mineral added by special cells in the bird’s uterus, encloses the gelatin-like mass of protein and embryo, slowly hardening into the egg’s shell. Egg shells are not completely solid, but are perforated with many minute holes that allow air to reach the developing embryo. Pigmentation is squirted onto the shell adding color and pattern to the outside. A coating of protein determines the outer texture of the egg which may be smooth, glossy, dull, rough, or powdery.

^{Egg collection, Jurica-Suchy Nature Museum, Benedictine University, Lisle by DonArnold}

The total number of eggs laid at one time is called a clutch and some bird species lay only one a year, but many species produce two, or more, annually. A consistent number of eggs is found in each clutch, although additional clutches in the same year may contain fewer eggs. Eggs vary widely in size, shape, and color among various bird species. Egg shapes may be determined by the location of the nest. Cavity nesters tend to have rounded eggs, while cliff dweller’s eggs are often oval with a broad end on one side and a pointed end on the other to prevent the egg from rolling very far. Where a clutch has a greater number of eggs, pointed shapes fit into smaller spaces enabling the mother to easily cover them all when sitting on the nest.

^{Nesting female hummingbird by jaypiercestorffphoto}

Incubation is the process of keeping the eggs warm. An adult usually develops a brood patch underneath its belly where feathers and down disappear and blood vessels close to the skin’s surface can warm the area that is in direct contact with the eggs. Incubation periods are consistent in each species, but may be lengthened by abnormal cold spells.

^{Blue robin eggs in nest by Dennis Flarsen, Pixabay}

^{Western bluebird eggs by Summit to Seashore Birding, Sep 2007}

Color is added into the shell material before it hardens. Colors may vary in hue and saturation on individual eggs, and the deepest hues are often found at the largest end. Pigments are chemicals with complex molecular structures that produce color when mixed with water. Birds have two pigments: reddish-brown hues and bluish-green hues. Here are several theories as to why eggs have markings, but exact reasons are not known.

Heavier pigments are often found in birds that lay their eggs in open, exposed environments, and the markings may serve as camouflage. Many cavity nesters lay white eggs, which are well hidden from other birds, predators, and the sun. Some eggs laid in exposed nests may still be brightly colored, but covered by the female most of the time.

^{Quail eggs showing pigmentation by Piyachok from Getty Images}

Darker colors and markings are often found among species that breed in cooler climates. Pigments are known to absorb UV radiation from the sun and not allow it to harm a developing embryo. But, light absorption by an area of pigmentation generates more heat inside the shell, which may also be harmful. Pesticides and other chemicals in the environment can cause thinning of the shell casing, making them more susceptible to breakage. Pigments tend to gather at weaker spots in the shell casing and have been shown to strengthen the shell.

Several aspects of bird egg development are not yet understood, and many theories are under investigation. An interesting question currently under review is whether a bird, or another animal such as a predator, sees different aspects of the light spectrum than humans. If so, what do birds see when they look at an egg? A new bird’s life starts in an egg, a small and wonder-filled package that has been much studied and yet still presents many unanswered questions.

To learn more, consider visiting your local nature museum.

The Jurica-Suchy Nature Museum at Benedictine University in Lisle, Illinois, has an extensive egg collection displayed by clutch size and covering almost 200 bird species.

Flamingos

The greater flamingo, Phoenicopterus roseus, with its long neck and legs, hooked downward bill, and bright pink plumage can be found on five of the seven continents, not including Australia or Antarctica. Only one of the six species is native to the continental U.S., the American greater flamingo, Phoenicopterus ruber, and its native range encompasses only the far southern portions of Florida. Three additional species are found in the Caribbean and northeastern and southwestern portions of South America, plus two species are native to coastal areas of Europe, Africa , and Asia.

Flamingos are found in all types of shallow water habitats. They forage in both saltwater lakes and coastal lagoons, in addition to freshwater wetlands, ponds, and mudflats. They are able to eat prey found in very alkaline waters that most other avian species cannot tolerate. Feral birds, ones that have escaped captivity and are now breeding in the wild, from the other three species found in North and South America have formed several colonies along the southeastern coast of the U.S.

The name flamingo comes from a Spanish word meaning flame, bright and red in color. Immature birds are gray or brown. They absorb carotene, a reddish-yellow pigment, from their food, which slowly changes their plumage to light pink, deepening to darker shades including reds and oranges. It takes about three years until a bird attains the bright pink adult plumage everywhere except their flight feathers which are jet black and can be seen only when their wings are extended.

^{Greater Flamingo chick in water by JHVEPhoto, Getty Images}

Flamingos have the longest neck and legs of any native bird in the U.S. Wingspans on full-grown adults may reach five feet. Flying in a V-formation, flocks move quickly, with necks extended, taking short, strong wingbeats. Flamingos call is a strong honking, sometimes hard to distinguish from geese, to maintain the group’s cohesion in flight. Webbed feet provide stability on soft sand, mudflats, and in shallow waters along lake bottoms. Flamingos are excellent swimmers, and they use their webbed feet to stabilize their bodies in the water when reaching downward for food growing in deeper lakes and ponds.

^{Flamingo head, by XavierMarchant, Getty Images}

A flamingo’s bill is sharply angled downward in the middle. On most birds, the upper bill is part of the bones of the head, heavier and immovable. On flamingos, this is reversed and the upper bill can be used as a flap against a heavy lower bill. When feeding, the bird lowers its head, turning the bill upside down, sweeping it from side to side through the water. A central groove in the lower bill contains space for a fat tongue, used to push and pull higher volumes of water through the bill. The edges of the bill are lined with rows of horny plates called lamellae that strain out crustaceans, mollusks, and small insects. Flamingos are typically night feeders, resting during the day.

Flamingos roost in single species colonies. They will only breed if they are part of a large group, and breeding occurs for all at the same time. Nest mounds are volcano-shaped, arranged close by one another on a mudflat. Each breeding pair of birds lays only one egg on top of its mound. Parents take turns incubating the egg while the other is foraging. Chicks stay with the parents for four to six weeks after hatching, until they are able to feed themselves. Still unable to forage and in need of protection, all of the chicks in larger colonies may form one group called a creche. The group can be guarded by only a few adults, giving the rest of the colony the opportunity to forage for themselves and bring back food for the creche.

^{Nesting Rose Flamingo with egg in nest, by Artush, Getty Images}

^{Chick and mother, by tane-mahuta, Getty Images}

Toward the end of the 1800s, feather collecting for the millinery markets adversely impacted many bird populations. However, this did not include flamingos because their feathers quickly lose the pink color once they are removed from the bird. Today, flamingo populations around the world are shrinking due to habitat loss. Much of their native habitat is wetland coastal areas being developed. In addition, flamingos do not have the capacity to switch diets, and as more wetlands are drained or polluted, food sources are continually disappearing.

Look for these magnificent birds at your local zoo, or consider a trip to see them in many of the nature areas in southern Florida.