  Data is the foundation for the development of computer vision, and the
establishment of datasets plays an important role in advancing the techniques
of fine-grained visual categorization~(FGVC). In the existing FGVC datasets
used in computer vision, it is generally assumed that each collected instance
has fixed characteristics and the distribution of different categories is
relatively balanced. In contrast, the real world scenario reveals the fact that
the characteristics of instances tend to vary with time and exhibit a
long-tailed distribution. Hence, the collected datasets may mislead the
optimization of the fine-grained classifiers, resulting in unpleasant
performance in real applications. Starting from the real-world conditions and
to promote the practical progress of fine-grained visual categorization, we
present a Concept Drift and Long-Tailed Distribution dataset. Specifically, the
dataset is collected by gathering 11195 images of 250 instances in different
species for 47 consecutive months in their natural contexts. The collection
process involves dozens of crowd workers for photographing and domain experts
for labelling. Extensive baseline experiments using the state-of-the-art
fine-grained classification models demonstrate the issues of concept drift and
long-tailed distribution existed in the dataset, which require the attention of
future researches.
