Conservation 

Double Crested Cormorant

The Great Lakes population of double-crested cormorants was devastated during the 1960s, primarily by the effects of chemical contamination especially DDT, which ingested from the fish they ate. These chemicals caused reproductive failure, and chicks that hatched sometimes had crossed bills, club feet, and eye and skeletal deformities. In addition to contamination nest destruction contributed to the decline. In the 1800s and early 1900s, cormorants were frequently shot, and their numbers declined with westward settlement. In Wisconsin, the species was placed on the list of threatened and endangered wildlife. Nesting platforms were erected to aid their recovery. In 1972, double-crested cormorants were added to the list of species protected by the 1918 Migratory Bird Treaty Act. The use of chemical was banned. Since the 1970s, cormorant populations have grown steadily, even explosively. Today, the Great Lakes population of double-crested cormorants is at historic highs. Pollution control has lowered concentrations of toxic contaminants in their food supply, food is ample throughout their winter and summer ranges, and they are protected by federal and state laws. Nesting populations can be found on all the Great Lakes in both United States and Canadian waters, on inland lakes like Lake Champlain and Oneida Lake, and on the Niagara River. In the Great Lakes, some cormorant colonies have doubled in five years. The U.S. Fish and Wildlife Service will cooperate with state and federal fish and wildlife management agencies to develop a regional management plan for double-crested cormorants. While the plan is being developed, the Service is preparing a comprehensive assessment of the population status of cormorants, and a review of the impacts of double-crested cormorants on commercial and sport fish populations in both natural and artificial settings.

Sources

Wikipedia

www.allaboutbirds.org/guide/double-crested_cormorant/id

http://www.fws.gov/

Reproduction

Magnificent frigatebird

The males attract their mates by perching on small plants, fluttering their wings and bending back their necks to inflate a bright red throat sac.  Males then drum this inflated sac with their own bills to create a signature clattering sound. Once bonded, the pair remains monogamous.The lifespan of Magnificent Frigate birds is expected to be 30 years. Frigatebirds nest in colonies.  Males gather sticks, which the female uses to construct a nest for the single egg she will lay. Clutch size of the magnificent frigatebird is one egg, and the incubation period lasts between 53 and 61 days. After the chick hatches, the male remains an additional month before leaving. The mother cares for her chick for another 13 months, providing it with stolen meals. Frigatebird chicks are altricial and require about six months to fledge.

Northern Gannets

Northern Gannets are the seabirds which belong to Sulidae family. They are colonial but are territorial. The most typical display is the “sky-pointing” with neck, head and bill held upwards. Both mates touch their bills and sometimes shake their heads to communicate. Pair-bonds last all the life and pairs return to the same nesting area each year.Northern gannets live for around 16-21 years. They breeds in huge colonies on sea-cliffs. They breeds a chalky blue egg on islands and coasts.  The clutch is typically 2 eggs. Incubation by both parents lasts 44 days. They do not have brood patches, but their feet become vascularized and hot, and incubate the egg with its webbed feet. At hatching, the chick is near-naked and brooded for the first days. Then, it is covered in white down on the black skin. Youngs are altricial and fledge after 90 days. 

sources

wikipedia

http://www.oiseaux-birds.com

Vocalization

The Double-crested Cormorant that I saw on first trip on shark river estuary  makes deep, guttural grunts that sound a bit like an oinking pig. They grunt when taking off or landing, or during mating or aggressive displays, but otherwise are generally silent.  The sound is like tup tup tup ki ki ki ki.

http://www.youtube.com/watch?v=ZYN2yK6OB_g

Anhinga

Anhinga’s call is a raspy croaking. Its calls consist of clicks, croaks and grunts. A series of rapid clicks that sound mechanical, like a sewing machine.the sound is like kiii kii kiirrr kiii kii kiirrr. It usually calls near or on the nest, or during the flight or while perching. Usually, Anhinga is a quiet bird.

http://soundbible.com/899-Anhinga.html

Morphological characteristics and Systemmatics

According to the Hackett Taxonomy, loons, penguins, storks, and as well as Suliformes and Pelecaniformes, all seem to have evolved from a common ancestor. The Order Suliformes is a proposed order by the International Ornithologist's Union. Suliformes includes 4 families, 6 genera and 15 species according to Eastern North America. Members of this order are Cormorants (Family: Phalacrocoracidae), Anhinga (Family: Anhingidae), Booby and Gannets (Family: Sulidae), Frigate birds (Family: Fregatidae). They are medium to large sea-birds usually found over tropical oceans. They prefer fresh water wetlands, ponds, rivers for habitat. They are mostly fish and small aquatic animal eaters. They have webbed feet. 

Anhinga's feet

                  For Cormorants and Anhingas, A major characteristic that unites them is the lack of an oil gland for waterproofing their wings. Thus they are often seen with their wings spread out to dry their feathers. The Anhinga is frequently seen soaring high in the sky overhead. It is a graceful flier and can travel long distances without flapping its wings, much in the manner of a Turkey Vulture.  Anhinga swims lower in the water than many other birds due to its reduced buoyancy a result of wetted plumage and dense bones. They have impressive fishing technique: diving and chasing fish underwater with powerful propulsion from webbed feet.

           Sulidae have long, narrow and pointed wings, and a quite long, graduated and rather lozenge-shaped tail whose outer feathers are shorter than the central ones. Their flight muscles are rather small to allow for the small cross section required for plunge-diving, and thus their wing loading is high.

                                                  Male Frigatebird on top, female on bottom

A long-winged, fork-tailed bird of tropical oceans, the Magnificent Frigatebird is an agile flier that snatches food off the surface of the ocean and steals food from other birds. Frigatebirds produce very little oil and therefore do not land in the ocean. The gular sac is used as part of a courtship display and is, perhaps, the most striking frigatebird feature. The males have inflatable colored throat pouches. the females have a white patch on her underside.

Sources
google images
wikipedia