Open-vocabulary recognition remains a challenging problem in computer vision, as it requires identifying objects from an unbounded set of categories. This is particularly relevant in nature, where new species are discovered every year. In this work, we focus on open-vocabulary bird species recognition, where the goal is to classify species based on their descriptions without being constrained to a predefined set of taxonomic categories. Traditional benchmarks like CUB-200-2011 and Birdsnap have been evaluated in a closed-vocabulary paradigm, limiting their applicability to real-world scenarios where novel species continually emerge. We show that the performance of current systems when evaluated under settings closely aligned with open-vocabulary drops by a huge margin. To address this gap, we propose a scalable framework integrating structured textual knowledge from Wikipedia articles of 11,202 bird species distilled via GPT-4o into concise, discriminative summaries. We propose Visual Re-ranking Retrieval-Augmented Generation(VR-RAG), a novel, retrieval-augmented generation framework that uses visual similarities to rerank the top m candidates retrieved by a set of multimodal vision language encoders. This allows for the recognition of unseen taxa. Extensive experiments across five established classification benchmarks show that our approach is highly effective. By integrating VR-RAG, we improve the average performance of state-of-the-art Large Multi-Modal Model QWEN2.5-VL by 15.4% across five benchmarks. Our approach outperforms conventional VLM-based approaches, which struggle with unseen species. By bridging the gap between encyclopedic knowledge and visual recognition, our work advances open-vocabulary recognition, offering a flexible, scalable solution for biodiversity monitoring and ecological research.
View on arXiv@article{khan2025_2505.05635,
title={ VR-RAG: Open-vocabulary Species Recognition with RAG-Assisted Large Multi-Modal Models },
author={ Faizan Farooq Khan and Jun Chen and Youssef Mohamed and Chun-Mei Feng and Mohamed Elhoseiny },
journal={arXiv preprint arXiv:2505.05635},
year={ 2025 }
}