ornithologist

例句：

1. 1. He is an expert in ornithology.
   他是鸟类学的专家。
2. 2. The researcher has made significant contributions to the field of ornithology.
   这位研究者为鸟类学领域做出了重大贡献。
3. 3. Ornithologists study the behavior and ecology of birds.
   鸟类学家研究鸟类的行为和生态。