📝 SummarXiv

Abstract

Open-vocabulary species recognition is a major challenge in computer vision, particularly in ornithology, where new taxa are continually discovered. While benchmarks like CUB-200-2011 and Birdsnap have advanced fine-grained recognition under closed vocabularies, they fall short of real-world conditions. We show that current systems suffer a performance drop of over 30\% in realistic open-vocabulary settings with thousands of candidate species, largely due to an increased number of visually similar and semantically ambiguous distractors. To address this, we propose Visual Re-ranking Retrieval-Augmented Generation (VR-RAG), a novel framework that links structured encyclopedic knowledge with recognition. We distill Wikipedia articles for 11,202 bird species into concise, discriminative summaries and retrieve candidates from these summaries. Unlike prior text-only approaches, VR-RAG incorporates visual information during retrieval, ensuring final predictions are both textually relevant and visually consistent with the query image. Extensive experiments across five bird classification benchmarks and two additional domains show that VR-RAG improves the average performance of the state-of-the-art Qwen2.5-VL model by 18.0%.