Southeastern American Kestrel in Louisiana

September 10, 2013 by  
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The American Kestrel (Falco sparverius) is the smallest member of the family Falconidae in North America. The American Kestrel can be identified by two distinct black streaks on each side of the head that contrast with the white throat and cheeks, and by a blue-gray patch encircling a rufous-colored spot on the top of the head. The males have a prominent rufous coloration on the back and tail. The Southeastern American Kestrel (F.s. paulus), which is one of two subspecies that occurs in the United States, is a local resident of Louisiana. It is approximately the size of a robin, and the female is larger than the male. The Southeastern American Kestrel (SAK) is often seen during the winter months in Louisiana perched on telephone lines located along fields and pastures.

The resident SAK is often confused during the winter with the migratory subspecies F.s. sparverius, although the resident species is smaller. The mean body mass of the SAK is approximately 22 percent lower in males and 26 percent lower in females, as compared to the migratory subspecies. It is very difficult to distinguish the two subspecies in the field. F.s. sparverius may look chunkier, but it takes someone who has spent long hours in the field watching kestrels to determine the difference between the two subspecies.

SAKs form strong pair bonds that tend to remain permanent. Displaying high site fidelity, pairs often remain on or near their nesting territories. SAK territories can range in size from 300 to 700 acres. In Louisiana, the SAK prefers open, park-like pine forest and open areas with scattered mature trees, which are needed for perch and nest sites. It is important that forest stands do not have a dense understory. The SAK prefers the same type of habitat preferred by the endangered Red-cockaded Woodpecker (RCW).

The SAK begins breeding courtship in late winter. The courtship includes aerial displays in which the male performs dives and a flutter-glide to advertise to the female. The SAK nests in cavities located in snags or living trees, usually excavated by woodpeckers. The Pileated Woodpecker often plays on important role in creating cavities suitable for nesting SAKs by enlarging the cavities of smaller woodpecker species. The SAK will also use nest boxes, when they are placed in suitable habitat. On Fort Polk, we usually find our first eggs in early April, and a full clutch usually consists of four to five eggs. The incubation period lasts 29 to 30 days. The young will fledge around the age of 30 days. The adults and young will forage together until dispersal, which occurs in the fall.

The SAK hunts from a perch, on the wing, and hovering. It is a generalized predator, feedings on rodents, insects, reptiles, amphibians, and small birds. The favorite food items on Fort Polk are lizards, including anoles, fence lizards, and skinks.

The U.S. Fish and Wildlife Service formerly considered the SAK a candidate subspecies for listing as threatened or endangered. It is no longer being considered a candidate for listing, but is considered a species of concern. The SAK is listed as threatened in Florida by the state’s game and fish commission. The SAK is a nonmigratory resident of the gulf coast states, now very rare over much of its former range. Current range includes east Texas, Florida, Louisiana, and the southern portions of the states of Mississippi, Alabama, South Carolina, and Georgia. The ranges of the two subspecies overlap during the winter.

Habitat loss is the main factor in the population decline of SAK in parts of its range. Industrial forest lands provide open areas important for the SAK, but they do not provide mature trees for nests sites. When the timber matures, the timber stand is usually too dense to be suitable for the SAK. Lack of prescribed fire is also detrimental to the SAK, because it prefers open, park-like forest stands kept open by regular prescribed burning. Prescribed burning and placing nest boxes in suitable habitat are the quick and feasible ways to improve SAK habitat.

Contributed by: Kenneth Moore

Also by Kenneth Moore: Southeastern Kestrel Management on Fort Polk

Common Barn Owl (Tyto alba)

February 9, 2009 by  
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The Common Barn Owl (Tyto alba) is one of two groups of owls. It belongs to the barn owl family Tytonidae and is a fairly common sight in rural areas across the globe. The Barn Owl may be found in any country except Antartica, although it may vary in appearance in certain instances such as the Tyto alba alba of western Europe which has a pure white underbelly or the Tyto alba guttata of central Europe which has an orange underbelly. These two variations are classified as subspecies and most Barn Owls have a mixture of grey and ochre on their underparts.

Barn Owls are generally pale in appearance and have long wings and fairly long legs. Their bodies measure between 33-39 cm in length and they have an average wingspan of 80-95 cm. They prefer open country, such as farmland or the edges of woods where they can easily spot their prey from the air. They generally hunt in the early twilight or at night and are fairly sedentary for the rest of the time. They often feed on voles, frogs, rats, shrews, moles, mice and insects. As they feed on so many pests, they are considered to be economically valuable birds and their presence is generally welcomed by farmers who may set up nesting sites for the birds to entice them to nest on the property. The Barn Owl is also known by several other names such as the ‘church owl’, ‘golden owl’, ‘stone owl’ and ‘rat owl’.

This beautiful, heart-faced bird has few natural predators, although they have been known to be preyed upon by bigger owls on occasion. Barn Owls themselves will prey on smaller birds if other food is scarce. They can emit a notable shrill scream which can be piercing at close range. They also hiss if nervous but do not make the ‘tu-whit to-whoo’ sound commonly associated with owls. If a Barn Owl is captured or cornered, it will flip itself on its back and use it’s sharply-taloned feet in defence. These incredible birds are also known for their soundless flight and excellent vision – especially at night.

Northern Gannet (Morus bassanus)

February 9, 2009 by  
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The beautiful Northern Gannet (Morus bassanus) is one of the three gannet subspecies that are found in the world. While the Northern Gannet is commonly found in the North Atlantic, the other two species are found on the south coast of Africa and in Tasmania and New Zealand so it is unlikely that you will wrongly identify them. These birds are rather unique since they can see forward with both eyes (binocular vision) – something which not many bird species are capable of. They are also powerful and fast flying birds who are capable of gliding just above the surface of the water for hours – though they do not take off or land well. They are excellent divers and eat small fish such as herring, mackerel, capelin, sandlance and sometimes on squid which can be found near the surface of the water. Northern Gannets have also been called ‘solan’s’, ‘solan geese’ and ‘solant birds’.

The adult gannet has striking white plumage with narrow grey spectacles and jet-black wingtips that taper to a point. During breeding season their head and neck take on a delicate yellow tint that contrasts with their blue eyes and blue-grey bills beautifully. Males and females look the same and juveniles are brown with white flecks. These youngsters get progressively whiter each season until they get their adult plumage at the age of four or five. Adults are 87-100 cm in length with a wingspan of 165-180 cm. Gannets are migratory and normally spend their winters at sea. However, during breeding season they will head to their breeding grounds – usually to the same nest until it is simply too filthy to use – where they perform elaborate greeting rituals with their partner.

Gannets live in large groups called gannetries, which can be found on steep cliffs or offshore islands. This isolation from land or steepness means that nesting birds are usually safe from predators. Northern Gannets will often abandon their nests if they are disturbed. Often nesting birds will nest so closely at these colonies that the cliff may appear to be covered in snow. The female lays a single egg, which both parents incubate. After hatching both parents care for the chick until it is old enough to fend for itself. Once it has left the nest, it learns the specialised ‘plunge-diving’ technique through instinct.

New Subspecies Discovered in Columbia

June 18, 2008 by  
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The more than 100 kilometer long Serrania de los Yariguies Mountain Range in Columbia has remained unexplored until fairly recently when, under the auspices of Fundacion ProAves, researchers began a survey focusing mainly on the birdlife in the area. So far, these efforts have yielded two new bird species and a new species of butterfly. The first new bird discovery has been named the Yariguies Brush-Finch, while the latest discovery has been named in honor of conservationist Robert Giles – Scytalopus griseicollis gilesi.

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Have you Considered Birding in Taiwan?

April 30, 2008 by  
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Not many people think of taking a birding trip to Taiwan, but this interesting country is home to a wide variety of bird species. Situated on the western edge of the Pacific Ocean, Taiwan is about 400 km long and 150 km wide. It features about 1000 km of coastline, a dense and scenic mountain range that rises to 3 998 m at its highest point and wide fertile agricultural plains. This is the perfect place to combine birding with culture, history and natural beauty.

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