* Classification of birds: He proposed a new system for classifying birds based on their geographical distribution, which became the foundation for modern avian taxonomy.
* Zoogeography: He studied the distribution of animals around the world and was one of the first to recognize the importance of biogeographic regions.
* Conservation: He was a strong advocate for the protection of endangered species and played a key role in the establishment of the Zoological Society of London.
Some of his major written works include:
* "A Monograph of the Birds of the Family Megapodidae, or Mound-builders" (1866): This book was a comprehensive study of the megapode birds, a family of ground-dwelling birds that build mounds for their nests.
* "Report on the Birds Collected by the British Museum Expedition to the Amazons" (1870): This report detailed the findings of a scientific expedition to the Amazon rainforest, including the discovery of many new bird species.
* "The Geographical Distribution of Animals" (1874): This book was a groundbreaking work on zoogeography, summarizing Sclater's extensive research on the distribution of animal species around the world.
* "The Birds of South America" (1901-1906): This multi-volume work was a major contribution to the study of South American ornithology.
In addition to these works, Sclater published numerous scientific papers and articles on a wide range of ornithological topics. He was also a prolific editor and contributed to several journals, including the *Proceedings of the Zoological Society of London*.
Overall, Philip Lutley Sclater was a highly influential figure in the field of ornithology, whose writings and research continue to be valued by scientists today.