A set of 800 images of birds from two distinct regions: the Eastern US and the British Isles.
A set of 208 images hand-picked from the CUB-200 dataset [3]. There are 16 different bird species with 13 images each [2].
A set of 360 images of rocks drawn from 30 different rock subtypes. There are 10 subtypes for each of three major classes: igneous, metamorphic, and sedimentary rocks. The actual images are available at https://osf.io/w64fv/ [1].
[1] Nosofsky, R. M., Sanders, C. A., Meagher, B. J., & Douglas, B. J. (2018). Toward the development of a feature-space representation for a complex natural category domain. Behavior research methods, 50(2), 530-556.
[2] Roads, B. D., & Mozer, M. C. (2019). Obtaining psychological embeddings through joint kernel and metric learning. Behavior Research Methods. doi: 10.3758/s13428-019-01285-3
[3] Wah, C., Branson, S., Welinder, P., Perona, P., & Belongie, S. (2011). The Caltech-UCSD Birds-200-2011 Dataset (Tech. Rep. No. CNS-TR-2011-001). California Institute of Technology.