Statement 1 is Correct: The Gharial (Gavialis gangeticus) is listed as Critically Endangered on the IUCN Red List. It has faced a drastic population decline due to habitat loss, prey depletion, and entanglement in fishing nets.

Statement 2 is Correct: The Leatherback turtle (Dermochelys coriacea) is categorized as Vulnerable globally on the IUCN Red List. In India, it is a high-priority conservation species found primarily in the Andaman and Nicobar Islands and is protected under Schedule I of the Wildlife Protection Act, 1972.

Statement 3 is Correct: The Swamp deer (Rucervus duvaucelii), or Barasingha, is listed as Vulnerable on the IUCN Red List. It faces threats from habitat fragmentation and conversion of grasslands to agricultural land.

In the context of this UPSC question, the term "endangered" is used as a general descriptor for species facing a significant threat of extinction. Under the IUCN Red List, the categories of Critically Endangered (CR), Endangered (EN), and Vulnerable (VU) are collectively referred to as 'Threatened' species. Since all three animals fall into these high-risk categories and are protected under Schedule I of India's Wildlife Protection Act, they are all considered endangered in the broader sense of the term.