Thank you Bryon for this nice cover from the USA.  Unfortunately, it appears and it made contact with water during its transportation.  The stamps were issued in 2005 and they are part of the Northeast Deciduous Forest.  One of them is showing Eastern Red Bat (Lasiurus borealis).  I will present the birds only.  From left to right:
Ovenbird (Seiurus aurocapillus): It is a North American Warbler leaving in forests.  It has three subspecies.
Wild Turkey (Meleagris gallopavo): We have seen this species in the past.
Red-shouldered Hawk (Buteo lineatus): It can be found in the USA and in Mexico.  It has five subspecies.  It feeds on small birds, small mammals, large insects, reptiles and amphibians.  Some  of the northern populations migrate to central Mexico in the winter.

Hello everyone, today I will present this cover sent to me from USA, thank you Michael. The whole Hawaiian Rain Forest set is used. It was released in September 2010 and as you can see it was sent to Hawaii for the special first day postmark. Five of the ten stamps depict birds and four of the five species are presented for the first time on stamps. From left to right:
Apapane (Himatione sanguinea): This finch is endemic to Hawaii. It mostly feeds on nectar from flowers but it can also eat insects.
Omao (Myadestes obscurus): This thrush is also endemic to Hawaii and it is listed as vulnerable. It feeds on fruit, berries, snails, insects and flower bracts.
Akepa (Loxops coccineus): Also endemic to Hawaii, this bird has three subspecies but only Loxops coccineus coccineus has not been extinct. It feeds on small caterpillars which it finds on 'Ohi'a-lehua trees leaf buds. It also feeds on this tree's nectar and on insects and arthropods it finds on koa trees.
Hawaii Amakihi (Hemignathus virens): It is endemic to Hawaii too. It is one of the most common honeycreepers there. This finch eats nectar, juices from fruit, insects and spiders.
Iiwi (Vestiaria coccinea): This endemic to Hawaii Hawaiian hummingbird-niched species is endangered. It feeds on nectar and small arthropods.

This set was issued in 1998 by USA.
Antillean Euphonia (Euphonia musica): This finch can be found in tropical and subtropical dry forests in islands of Antilles. It mainly eats berries.
Green-throated Carib (Eulampis holosericeus): This hummingbird is located in the Caribbean region. It has two subspecies.
Akohekohe or Crested Honeycreeper (Palmeria dolei): This finch is endemic to Hawaii's island Maui and it can be found in its wet forests. It feeds on nectar and insects. Its main source of food is the nectar of the Metrosideros polymorpha. It is an endangered species.
Cardinal Honeyeater (Myzomela cardinalis): It is located in Vanuatu, American Samoa, Samoa and Solomon Islands. It feeds mostly on nectar.

Here is another cover from USA badly postmarked. The bird stamps from left to right were issued in 1969, 1971, and 1994. The last two were a joint issue with China. We already talked about California Condor so I will focus on the other three stamps.
Northern Flicker (Colaptes auratus): It is a member of the woodpecker family. This migratory bird lives in North and Central America in woodlands. It has three subspecies of which one is unfortunately extinct. It feeds on insects, fruit, berries, nuts and seeds.

Whooping Crane (Grus americana): It lives in North America and it is an endangered species. They feed on crustaceans, mollusks, aquatic insects, fish, frogs, snails, small rodents, berries etc.

Black-Necked Crane (Grus nigricollis): It lives in Asia and it is an endangered species. Like all cranes, they are too omnivorous.

Here is a cover from USA with a Ring-necked Pheasant stamp used for postage. The stamp was issued in 1988. This species was already presented in a Chinese cover.