Bangladeshi Finches with their Evolutionary Thoughts (Aves: Passeriformes)

Abbreviations

LC: Least Concern; CR: Critical Endangered.

Natural History of Finches

Finches are the largest group of small song birds in the world. British and European finches include the bullfinch, chaffinch, greenfinch, goldfinch, sparrow, brambling, crossbill, linnet, and many others. All finches of Bangladesh are found easily with remarkable number. Left over feed is occasionally their secondary source of feed. In addition, many insects and ripe fruits are found adequate in the country. Due to frequent urbanization many wild birds are found like tame, so it is possible to know their natural history. Siddiqui KU, et al. [1] mentioned the subspecies of the finches of Bangladesh. Darwin’s finches are famous as an example of adaptive radiation. Population sizes and number of species are limited in Galapagos Islands and allows easy observation with different habitats. Ground finches and tree finches are two bigger ecological groups in these lands [2]. Short eared owls, Galapagos hawks, lava herons, and cats are the predator of Darwin’s finches, and egg-eating predators are mainly larger birds and snakes as well [2].

Finches of Bangladesh

Bunting: These birds are colourful like other finches in the world. It has conical beak that allows taking seeds as their feed, and is similar to sharp-beaked Darwin’s finches of Galapagos Islands. In Bangladesh, there are five bunting species, and global and Bangladesh status are critical endangered (CR) and vulnerable (VU). Based on the plumage colour of the subspecies of Emberiza fucata (head gray, upper parts chestnut) and E. f. kuatunensis (darker and more rufous above with narrower breast bands) possible to isolate from each other. All buntings are more of less rare and winter migrant in Bangladesh (Figure 1).

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Baya Weaver

These weavers are known weaver finch due to its finch- like beaks, and it well-known for its pendulous type of nest. Genetic factors are precursor to make this nesting ability. In breeding season, males are focused themselves with brilliant plumages to the females for mating. These are least concern (LC) bird. Beak size and length is comparatively big in these birds than other finch species of Bangladesh. Two subspecies of streaked weaver bird, Ploceus manyar flaviceps (paler, less rufous above) and P. m. peguensis (darker, more rufous above) differs by their plumages. Baya weaver birds (Ploceus philippinus) are very common breeding birds in Bangladesh [3] (Figure 2).

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Munia

Munias are common passerine birds in Bangladesh. Some wild finches (Lonchura Malacca, L. malabarica, L. punctulata) are kept in Bangladesh as recognized cage birds [4]. In an aviary, it is possible to breed them successfully. In our local markets or in pet shops, sometimes, animal traders sell these wild birds illegally. Its conical beaks are responsible to take seeds from the ground. This bird is least concern bird (LC) in both global and Bangladesh affairs. These Bangladeshi munias can be compared with the Darwin’s finches which are sharp-beaked ground finches and medium ground finches (Figure 3).

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Sparrow

Sparrows as well as house sparrows are very common throughout Bangladesh. Human dwelling and electric poles are their dominant and successful breeding place. Its conical beak helps to take seeds but due to live near human habitat, it takes rice and other kitchen materials too. In addition, these sparrows are helpful to control pests of crop-fields. Tree sparrows are not common like house sparrow. This is slightly smaller than house sparrow and a shy bird (Figure 4).

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Rose Finch

This is another group of finches. In world, it has many species but in Bangladesh, only one species is observed. Bright red plumages are their main identity. Conical beak allows taking seeds. Sharp-beaked ground finch of the Galapagos Islands is similar to this rose finch of Bangladesh (Figure 5).

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Studies on Habitats and Beaks of Finches

It is easy to understand the relation between the beak size or beak types with the feeding habit of finches. Some different species were more or less the same with these beaks, habitats, and feed habits. Through the study in the evolutionary changes on the beak of Bangladeshi finches then the comparison with the Darwin’s finches, it could be known the origin of these finches. There are large variations in beak sizes between the same species on different islands of Darwin’s finches [5, 6]. Long and potential beaks are the best for probing during catching feed. Beak size and shape are highly heritable between Darwin’s finches [2]. Types of feed and habitat influence to change their beak size that allows speciation finally (Table 1, Figure 6).

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Conclusions

As finches are evolutionary birds, so this is urgent to take necessary studies on its ecosystem diversity. These birds have numerous subspecies in the world as well as Bangladesh.

Remarkable changes on their plumage colours, beak sizes, feed habit, and habitat could ensure different species later on. Birds in the family Passeridae, Estrildidae, Emberizidae, Ploceidae, and Fringillidae are considered finches. Skin taxidermy, dry- and wet-preserved museum specimens of colleges, universities, and national museum could play a significant role to study such evolutionary changes of finches. Due to different environmental and genetic factors, such changes act as a raw material for speciation.