Peruvian Pelican

Peruvian Pelican - Spec. Name:  Pelecanus Thagus

This is a member of the pelican family. It lives on the west coast of South America, from Lobos de Tierra Island in Peru to Pupuya Islet in Chile.

These birds are dark in colour with a white stripe from the top of the bill up to the crown and down the sides of the neck. They have long tufted feathers on the top of their heads. It used to be considered a subspecies of the Brown Pelican (Pelecanus occidentalis). The Peruvian birds are nearly twice the bulk of the Brown Pelican, averaging 15.4 lb (7 kg) in weight; they are also longer, measuring about 5 ft (1.5 m) overall.

The main breeding season occurs from September to March. Clutch size is usually two or three eggs. Eggs are incubated for approximately 4 to 5 weeks, with the rearing period lasting about 3 months.

This bird feeds on several species of fish. It feeds by diving into the water from flight, like the Brown Pelican.


Its status was first evaluated for the IUCN Red List in 2008, being listed as "Near threatened".

Peruvian Pelicans

The photographs were taken at the port of Ancon in Peru by HJ Ruiz.

Brown-headed Cowbird

Brown-headed Cowbird - Spec. Name: Molothrus ater

This is a small brood parasitic * icterid of temperate to subtropical North America. They are permanent residents in the southern parts of their range; northern birds migrate to the southern United States and Mexico in winter, returning to their summer habitat about March/April.

Brown-headed Cowbird (M)

They resemble New World orioles in general shape but have a finch-like head and beak. Adults have a short finch-like bill and dark eyes. The adult male is mainly iridescent black with a brown head. The adult female is grey with a pale throat and fine streaking on the underparts.

They occur in open or semi-open country and often travel in flocks, sometimes mixed with Red-winged Blackbirds (particularly in spring) and Bobolinks (particularly in fall), as well as Common Grackle or European Starlings. These birds forage on the ground, often following grazing animals such as horses and cows to catch insects stirred up by the larger animals. They mainly eat seeds and insects.

Females

Before European settlement, the Brown-headed Cowbird followed bison herds across the prairies. Their parasitic nesting behaviour complemented this nomadic lifestyle. Their numbers expanded with the clearing of forested areas and the introduction of new grazing animals by settlers across North America. Brown-headed Cowbirds are now commonly seen at suburban birdfeeders.

Brrown-headed Cowbird (M)

* Explaining Brood Parasitism

Brood parasites are organisms that use the strategy of brood parasitism, a kind of kleptoparasitism found amongbirds, fish or insects, involving the manipulation and use of host individuals either of the same (intraspecific brood-parasitism) or different species (interspecific brood-parasitism) to raise the young of the brood-parasite. This relieves the parasitic parent from the investment of rearing young or building nests, enabling them to spend more time foraging, producing offspring etc. Additionally, the risk of egg loss to raiders such as raccoons is mitigated, by having distributed the eggs amongst a number of different nests.

As this behaviour is damaging to the host, it will often result in anevolutionary arms race between parasite and host.

In many monogamous bird species, there are extra-pair matings resulting in males outside the pair bond siring offspring and used by males to escape from the parental investment in raising their offspring.

This form of cuckoldry is taken a step further when females lay their eggs in the nests of other individuals. Intraspecific brood parasitism is seen in a number of duck species with females laying their eggs in the nests of others for example in the Goldeneye, Bucephala clangula.Interspecific brood-parasites include the Old World cuckoos in Eurasia and Australia, cowbirds and Black-headed Ducks in the Americas, and indigobirds, whydahs, and the honeyguides in Africa. Seven independent origins of obligate interspecific brood parasitism in birds have been proposed. While there is still some controversy over when and how many origins of interspecific brood parasitism have occurred, recent phylogenetic analyses suggest two origins in Passeriformes (once in New World cowbirds: Icteridae, and once in African Finches: Viduidae); three origins in Old World and New World cuckoos (once in Cuculinae, Phaenicophaeinae, and in Neomorphinae-Crotophaginae); a single origin in Old World honeyguides (Indicatoridae); and in a single species of waterfowl, the black-headed duck (Heteronetta atricapilla).

Eastern Towhee mouth feeding a female cowbird

Most avian brood parasites are specialists which will only parasitize a single host species or a small group of closely related host species, but four out of the five parasitic cowbirds are generalists, which parasitize a wide variety of hosts; the Brown-headed Cowbird has 221 known hosts. They usually only lay one egg per nest, although in some cases, particularly the cowbirds, several females may use the same host nest.The Common Cuckoo presents an interesting case in which the species as a whole parasitizes a wide variety of hosts, but individual females specialize in a single species. Genes regulating egg coloration appear to be passed down exclusively along the maternal line, allowing females to lay mimetic eggs in the nest of the species they specialize in. Females are thought to imprint upon the host species which raised them, and subsequently only parasitize nests of that species. Male Common Cuckoos will fertilize females of all lines, maintaining sufficient gene flow among the different maternal lines.

The mechanisms of host selection by female cuckoos are somewhat unclear, though several hypotheses have been suggested in attempt to explain the choice. These include genetic inheritance of host preference, host imprinting on young birds, returning to place of birth and subsequently choosing a host randomly (“natal philopatry”), choice based on preferred nest site (nest-site hypothesis), and choice based on preferred habitat (habitat-selection hypothesis). Of these hypotheses the nest-site selection and habitat selection have been most supported by experimental analysis.

Common adaptations of avian brood parasitesAmong specialist avian brood parasites, mimetic eggs are a nearly universal adaptation. There is even some evidence that the generalist Brown-headed Cowbird may have evolved an egg coloration mimicking a number of their hosts.

Most avian brood parasites will remove a host egg when they lay one of their own in a nest. Depending upon the species, this can happen either in the same visit to the host nest or in a separate visit before or after the parasitism. This both prevents the host species from realizing their nest has been parasitized and reducescompetition for the parasitic nestling once it hatches.Most avian brood parasites have very short egg incubation periods and rapid nestling growth. This gives the parasitic nestling a head start on growth over its nestmates, allowing it to outcompete them. In cases where the host nestlings are significantly smaller than the parasite nestling, the host nestlings will often starve to death. Some brood parasites will eliminate all their nestmates shortly after hatching, either by ejecting them from the nest or killing them with sharp mandiblehooks which fall off after a few days.

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Song Sparrow

Song Sparrow -  Melospiza Melodia 


This is a medium-sized American sparrow. Adults have brown upper-parts with dark streaks on the back and are white underneath with dark streaking and a dark brown spot in the middle of the breast. They have a brown cap and a long brown rounded tail. Their face is grey with a streak through the eye.

Song Sparrow

In the field, they are most easily confused with its congener the Lincoln's Sparrow, and the Savannah Sparrow. The former can be recognized by its shorter, greyer tail and the differently-patterned head, the brown cheeks forming a clear-cut angular patch. The Savannah Sparrow has a forked tail and yellowish flecks on the face when seen up close.

Although they are a habitat generalist, their favorite habitat is brushy areas and marshes, including salt marshes, across most of Canada and the United States. They also thrive in human areas, such as in suburbs, along edges in agricultural areas, and along roadsides. In southern locations, they are permanent residents. Northern birds migrate to the southern United States or Mexico, where there is also a local population resident all year round. The Song Sparrow is a very rare vagrant to western Europe, with a few recorded in Great Britain and Norway.

These birds forage on the ground, in shrubs or in very shallow water. They mainly eat insects and seeds. Birds in salt marshes may also eat small crustaceans. They nest either in a sheltered location on the ground or in trees or shrubs.

The Song Sparrow lays 3-5 eggs. The egg coloring is a brown spotted greenish-white.

The male of this species uses its melodious and fairly complex song to declare ownership of its territory and to attract females.

The Song Sparrow's song consists of a combination of repeated notes, quickly passing isolated notes, and trills. The songs are very crisp, clear, and precise, making them easily distinguishable by human ears. A particular song is determined not only by pitch and rhythm but also by the timbre of the trills. Although one bird will know many songs - as many as 20 different tunes with as many as 1,000 improvised variations on the basic theme, unlike thrushes, the Song Sparrow usually repeats the same song many times before switching to a different song.

Song Sparrows typically learn their songs from a handful of other birds that have neighboring territories. They are most likely to learn songs that are shared in common between these neighbors. Ultimately, they will choose a territory close to or replacing the birds that they have learned from. This allows the Song Sparrows to address their neighbors with songs shared in common with those neighbors. It has been demonstrated that Song Sparrows are able to distinguish neighbors from strangers on the basis of song, and also that females are able to distinguish (and prefer) their mate's songs from those of other neighboring birds, and they prefer songs of neighboring birds to those of strangers.

Other birds such as mockingbirds are not able to effectively imitate the Song Sparrow's song.