British Trust for Ornithology British Trust for Ornithology British Trust for Ornithology British Trust for Ornithology British Trust for Ornithology British Trust for Ornithology англ. British Trust for Ornithology British Trust for Ornithology British Trust for Ornithology British Trust for Ornithology British Trust for Ornithology British Trust for Ornithology British Trust for Ornithology British Trust for Ornithology British Trust for Ornithology