An avivore is a specialized predator of bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s, with birds making up a large proportion of its diet. Such bird-eating animals come from a range of groups.

Birds

Birds that are specialized predators of birds include certain accipiter

Accipiter

The genus Accipiter is a group of birds of prey in the family Accipitridae, many of which are named as goshawks and sparrowhawks. They can be anatomically distinguished from their relatives by the lack of a procoracoid foramen. Two small and aberrant species usually placed here do possess a large...

s and falcon

Falcon

A falcon is any species of raptor in the genus Falco. The genus contains 37 species, widely distributed throughout Europe, Asia, and North America....

s. General features of avian avivores include a skull form which is well adapted for grasping and crushing with the beak, although not especially well structured for neck twisting motions http://www.jstor.org/stable/4089021?seq=1. Bird-eating raptor

Bird of prey

Birds of prey are birds that hunt for food primarily on the wing, using their keen senses, especially vision. They are defined as birds that primarily hunt vertebrates, including other birds. Their talons and beaks tend to be relatively large, powerful and adapted for tearing and/or piercing flesh....

s also tend to show greater sexual dimorphism than other raptors, with the females being larger than the males http://www.jstor.org/stable/2461268.

Some avian avivores such as the Shikra

Shikra

The Shikra is a small bird of prey in the family Accipitridae found widely distributed in Asia and Africa where it is also called the Little Banded Goshawk. The African forms may represent a separate species but have usually been considered as subspecies of the Shikra...

, Besra

Besra

The Besra, Accipiter virgatus, is a bird of prey in the family Accipitridae.The Besra is a widespread resident breeder in dense forests throughout south Asia from Pakistan and India to south China and Indonesia. It nests in trees, building a new nest each year...

, Eurasian Sparrowhawk, and Sharp-shinned Hawk

Sharp-shinned Hawk

The Sharp-shinned Hawk is a small hawk. In fact, "sharp-shins" or "sharpies" are the smallest to reside in USA and Canada, though some Neotropical species are smaller...

 catch their prey by flying from cover in a tree or bush, taking their prey unawares. In contrast, the Lanner Falcon

Lanner Falcon

The Lanner Falcon is a large bird of prey that breeds in Africa, southeast Europe and just into Asia. It is mainly resident, but some birds disperse more widely after the breeding season.-Description:...

 hunts in open country taking birds by horizontal pursuit. The Aplomado Falcon

Aplomado Falcon

The Aplomado Falcon, Falco femoralis, is a medium-sized falcon of the Americas. The species' largest contiguous range is in South America, but not in the deep interior Amazon Basin. It was long known as Falco fusco-coerulescens or Falco fuscocaerulescens, but these names are now believed to refer...

 will use both ambush and more extended flights http://www.pima.gov/cmo/sdcp/species/fsheets/af.html. The Peregrine Falcon

Peregrine Falcon

The Peregrine Falcon , also known as the Peregrine, and historically as the Duck Hawk in North America, is a widespread bird of prey in the family Falconidae. A large, crow-sized falcon, it has a blue-gray back, barred white underparts, and a black head and "moustache"...

 dives on flying birds from a great height at speeds that can exceed 300 km/h.

The extinct Haast's Eagle

Haast's Eagle

Haast's Eagle was a species of massive eagles that once lived on the South Island of New Zealand. The species was the largest eagle known to have existed. Its prey consisted mainly of gigantic flightless birds that were unable to defend themselves from the striking force and speed of these eagles,...

 of New Zealand

New Zealand

New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

 preyed on the large flightless bird species of the region such as the Moa

Moa

The moa were eleven species of flightless birds endemic to New Zealand. The two largest species, Dinornis robustus and Dinornis novaezelandiae, reached about in height with neck outstretched, and weighed about ....

.

Mammal

A number of mammal species are specialized predators of birds. The caracal

Caracal

The caracal is a fiercely territorial medium-sized cat ranging over Western Asia, South Asia and Africa.The word caracal comes from the Turkish word "karakulak", meaning "black ear". In North India and Pakistan, the caracal is locally known as syahgosh or shyahgosh, which is a Persian term...

, a medium sized cat, is known for its leaping ability which it uses to catch birds, sometimes two at a time. The Greater Noctule bat

Greater Noctule bat

The Greater Noctule bat is a rare mammal found in Europe, West Asia, and North Africa. It is the largest and least studied bat in Europe with a wingspan of up to 46 centimeters and is one of the few bat species to feed on passerine birds. Greater Noctule bat is the only bat species to hunt birds...

 is believed to predate small migrating birds on the wing in the skys of southern Europe.

Many mammals, such as squirrel

Squirrel

Squirrels belong to a large family of small or medium-sized rodents called the Sciuridae. The family includes tree squirrels, ground squirrels, chipmunks, marmots , flying squirrels, and prairie dogs. Squirrels are indigenous to the Americas, Eurasia, and Africa and have been introduced to Australia...

s and pine marten

Pine Marten

The European Pine Marten , known most commonly as the pine marten in Anglophone Europe, and less commonly also known as Pineten, baum marten, or sweet marten, is an animal native to Northern Europe belonging to the mustelid family, which also includes mink, otter, badger, wolverine and weasel. It...

s, also feed on bird eggs and young when they get the chance.

Reptiles

The egg-eating snake specializes in eating birds eggs, swallowing them whole and then breaking them using a protrusion from its spine.

Amphibians

The fanged frog Limnonectes megastomias

Limnonectes megastomias

Limnonectes megastomias is a species of frog with fangs that was discovered in Thailand in 2008. The frog eats birds and insects. The male frogs use their fangs to attack other males in combat. The species have also been known to eat other frogs....

preys on birds and insects http://www.cbsnews.com/stories/2009/09/25/tech/main5338998.shtml.

Arachnids

The Goliath birdeater

Goliath birdeater

The Goliath bird-eater Spider is an arachnid belonging to the tarantula group, Theraphosidae, and is considered to be the second largest spider in the world , and they may be the biggest by mass...

(Theraphosa blondi) was named by explorers who saw it eating a humming bird