BirdWalk Newsletter

Transcription

1 BirdWalk Newsletter Walk Conducted by Perry Nugent Written by Jayne J. Matney Hark, love, while through this wood we walk, Beneath melodious trees, How wrens with redbreasts ever talk What tuneful words they please.. No graybeard linguist, love, could vie With our large learning, then! You d speak to me in Redbreast; I Would answer you in Wren! Edgar Fawcett, Bird-Language 1891 Photo by Guenter Weber

2 Nests and Nest Building: Our amazing and diverse avian friends seem to have equally diverse nest types and nest building behaviors. Having more than 700 species of birds in North America, we have an enormous array to choose from. A nest s primary function is for breeding and to care for eggs and young. Many times, they serve the birds other purposes such as roosting and protection. Most nests are rebuilt each year. However, some nests are reused from one year to the next. In most species, the female does most or all of the building of that nest. Not to slight the males, some males will begin the nest building in order to attract their mates, yet the females may Partnering up for nest building Photo by Cary McDonald eventually clean house and redo what has been done. Sometimes, the nest building process is a true partnership. Birdwatchers at Magnolia Plantation may see Great Blue Heron males gathering and bringing sticks to the female in order for her to keep on task with the nest building. The sights for the nests are primarily chosen based on protection from predators, availability for water and food, and proper materials. For some types of birds, human activity is a detriment, but for others, it is not. How do they know when it is time to nest? Most research shows that it has something to do with the

3 length of days, or photoperiodism, which triggers the bird s instinctual need to nest and breed. Great Egrets nesting Photo by John Nickerson Most ornithologists and avid bird watchers agree on the categories of nesting styles. Because the nests vary according to the size, materials used, shape, and location, the categories have been distinguished with these things in mind. The categories are: scrape, mound, burrow, cavity, cup, saucer/plate, platform, pendant, and sphere. The scrape is a shallow depression on the ground. It must be deep enough to keep the eggs from rolling away, but shallow enough not to fill with water. In order to prevent the eggs from sinking through mud or sand, or roll away, these types of nests are usually lined with feathers, vegetation, pebbles, or shell but in a minimal sense. Birds that are known to use this type of nest are the ducks, shorebirds, terns, quail, pheasants, etc. Some birds that nest on the ground have more vulnerabilities to predators, therefore they need to be camouflaged or have distraction behaviors or defensive behaviors in case a predator comes too close.

4 The mound is usually a giant heap of mud, vegetation such as leaves, sticks, and twigs, and soil. In some cases, this mound may take up to seven hours a day for more than a month in order to complete! Much like the mound nests made by alligators, the decomposition of these organic parts causes a type of compostlike pile which causes the mound to heat up. This natural incubator is a way for the birds to help regulate temperatures for the eggs. Unlike other types, most mound type nests are actually built, maintained, and temperature regulated by the male. The male will probe with its beak periodically and stick his head in to gage the inside temperature. If the mound is getting too hot inside, he will break away the top of the mound to allow heat to escape. He will re-seal opening when the mound is at the right temperature. If the mound is getting too cool, he will load up more debris to get the composting process cranked up. A few of the mound builders, such as flamingos, will deposit the eggs on top of the mound instead of inside. One mound nest, of a Horned Coot, is made of gathered stones placed in shallow water by beak until the cone tip is above water for depositing of the eggs. A burrow nest is also usually made of soil, but underground rather than above ground. This nest is either dug out of a dirt bank or cliff. Sometimes this type of nest is made from an existing but abandoned burrow from rabbits, gophers, prairie dogs, etc. The burrows can be quite short (only 20 inches) as in the burrows of some martins, or as long as 3-4 meters as with the burrowing parakeet. By using the vertical banks to make a horizontal burrow, the birds can prevent flooding of the nests and can monitor predators more easily. When making the burrow itself, different species take different approaches, but whether it is dug out by beak, feet, or body, the nests are excavated in good order and used by the female for her eggs. Cavity nests are very similar to the burrowing ones. These cavities can be found within breaks in boulders, in rotting tree trunks, tree stumps, or abandoned cavities of other cavity nesting birds. Cavity nests are in the category of nests where you see a lot of primary and secondary nesters. Primary nesters are those that actually make the nest the first time in that location while the secondary nesters borrow these nests-usually the second year since most cavity

5 builders only use the nest for one year. For example, woodpeckers pound and excavate on the sides of rotting trees for a horizontal canal first, then to a vertical chamber. After the first year of use, it will choose a different tree to pound and excavate. Thus, leaving the previous year s nest for a secondary nester. The biggest danger to this type of nesting is the fact that mom and young can get trapped inside by a predator rather easily. To prevent this, different species have come up with different precautions. High-resin trees can be used by the parent birds for making sap slick trunks. They bore holes above and below the nest openings to keep snakes and other predators from reaching the interior of the nest. Some nuthatchers may actually smear the openings with sap or smear anything foal-smelling to deter the predator. A cup nest is the most well-known type of nests. It can be described basically as a hollowed out ball that has been cut in half. Many passerines use this type of nest, and they are usually built very carefully and with intricate detail. They are made from readily accessible materials that can be bent and woven according to the bird s requirements. Grasses, feathers, fur, sticks, Spanish moss, mosses, mud, lichen, spider webbing, and saliva are top on the list. However, many birds have been observed using paper, plastic bags, and other human discards to their advantage. The size and weight of the nest has been researched and found to be directly related to the mass of the parent that incubates the nest. This seems logical as to make sure that the nest can support and house parent and eggs. The saucer/plate nest is similar to the cup nest except they are shallower. The sphere nest is almost an entire circle with only a small opening for the birds to go in and out. Like the cup, saucer, and pendant nest, they are weaves of many materials. The pendant nest can be described as a dangling or hanging nest usually in an elongated shape. Like the cup and saucer nests, the pieces are woven into an intricate home, but unlike the others it is suspended on a branch. The platform nest is a large structure usually elevated high up off the ground. Most platform nests are located in tall trees, while others may even be on a ledge of a cliff. Many platform nests will be reused each year by the same returning adults. Eagles, for example, will keep coming back to the same nest if

6 the territory is still sound. They will add new material to the previous year s nest. Fun Facts: The study of bird nests is called caliology. In China, bird s nest soup is considered a delicacy. It is made from nests made of bird saliva. The Beijing National Stadium-once used as the primary venue for the Olympic Games in was nicknamed The Bird Nest because of the architectural feel. The smallest bird nests are the hummingbird nests. They are usually tiny cups and can be only 2 cm across and 2 to 3 cm high! The dusky scrubfowl builds a mound nest that can measure more than 36 feet in diameter and 16 feet tall! Birds that lay eggs on rocky ledges have eggs that are pointed so that they will roll in a circle and not fall off the ledge! Some birds like to nest together in dormitory or roost nests during wintering or nonbreeding season. A penguins nest is the adults feet and body folds that lay over the feet. The endangered red-cockaded woodpecker takes up to 2 years to excavate its new nest, therefore it will reuse its nest until the next one is built. The African bird, Hamerkop, takes about 8 weeks to build its nest and uses 10,000 twigs to build! A bald eagle s nest is called a eyrie and is built in a large, tall tree or on a cliff so that their viewpoint can see danger from far away. The Baya Weaver male carefully weaves a pendant nest over water then shows off his expertise to the females. If the female approves, she will nest with him. Some birds such as grebe and some ducks make platform nest on a floating group of twigs and grasses. A common tailorbird is named for its nest building technique. The bird pierces the edges of leaves and then sews up these edges together with silk threading!

7 Information for article came from: nestwatch.org, bbc.com/earth, Wikipedia. Sunday, February 26 th, 2017, was a fabulous day with 67 species counted. The skies were clear, there was a slight nip to the air in the morning but warmed up to a pleasant temperature by morning, and the birds showed their delight for the day with plenty of activity and singing. The Hermit Thrush started the count in the parking lot. Canadian Geese White Ibis Photo by Marcie Daniels flew over at the Audubon Swamp, and Ring-billed Gulls and Herring Gulls flew up high near the river. Great Blue Heron were busy building nests and attracting their mates, while some of the Anhinga were already being seen pairing up and nesting. The Ravenswood and old river impoundment ponds were busy. Wood Duck, Gadwall, American Wigeon, Blue-winged Teal, Ringed-neck Ducks, Pied-billed Grebe, Double Crested Cormorant, Great Egret, Snowy Egret, Little Blue Heron, Tri-colored Heron, Green Heron, Black-crowned Heron, and White Ibis showed up for viewing. In addition, at least 50 Common Moorhen were established in the old river impoundment. Perry notes that in past years he has observed both moorhen and grebe with more than one clutch of babies. The older siblings can be seen helping out with the feeding and rearing of the younger siblings. This facilitates a learning process for the older siblings as practice for the following year. At least 100 American Coot were in a large cluster at the old river impoundment moving back and forth between the cover of the grasses and the open water depending upon the location of the eagles in the area. They have had to be very conscientious about watching for these predators, because the

8 bird watching group has been seeing 2 adult Bald Eagle, 2 third year birds, and 1 juvenile bird. Coots on the RUN! Photo by Jo Frkovich A Northern Harrier has also been seen flying over the old impoundment, while the Red-shouldered Hawks seem to prefer the other side of the property near the exit road and cabins. The Gray Catbird was also seen near the cabins. Perry reminds us that these birds are very secretive and elusive as well as difficult to see in the dark shadows. Ravenswood also housed 2 Wood Stork on this particular morning. The vultures are once again in high numbers with 35 Black Vulture and 12 Turkey Vultures. A pleasant surprise was the addition of the Wilson s Snipe this week along the edge of the impoundment. Our surprise for a species NOT seen this week was the Green-winged Teal. 10 Red-bellied Woodpecker sightings were made as well as 4 Downy Woodpecker sightings. Yellow-bellied Sapsucker and Northern Flicker also made the list.

9 2 Pileated Woodpeckers were wonderful observations for the group; they lit on a tree near the observation tower in clear view and in the sunlight. There were five types of warbler identified: Yellow-rumped, Yellowthroated, Pine, Palm, Black-and white. Four sparrow species were also noted: Chipping, Song, Swamp, and the White-throated. A rare sight, simply because they are so difficult to see due to their incredible camouflage, was the Brown Creeper found on a tree along the wooded, dirt trail between the cabins and Ravenswood Pond. A large flock of American Robin were observed along the Indian mound road. Another very large flock of over 200 Yellow-bellied Sapsucker Tree Swallows glided above the old rice Photo by Norma M. Armstrong impoundment and into the grasses for periodic rests. According to Perry, these swallows will congregate in the cattails during the cooler evenings and nights. American Goldfinch found more elm tree seeds to eat upon this week. The birdwatchers located a mixed flock of Red-winged and Rusty Blackbird with 1 Brown-headed Cowbird in tow. The Carolina Wren were scattered about the property singing to be recognized. Other species to top off the final count: Mourning Dove, Belted Kingfisher, Eastern Phoebe, White-eyed Vireo, Blue Jay, American and Fish Crow, Carolina Chickadee, Tufted Titmouse, Ruby-crowned Kinglet, Eastern Bluebird, Northern Mockingbird, Northern Cardinal, Common and Boat-tailed Grackle. Just Chillin Photo by Jo Frkovich