I think you just make the ecology portion of any biology course as interesting as possible. Any fieldtrip is a winner, and any contact with living things I think is also a winner. One can, at the least, show students a variety of protists--buy some or make enrichment cultures from local ponds, to blow students' minds with huge numbers and decent diversity of protozoans swimming around. They can take photos with their phones and you can post them on your website. You can also get into some ecology by watching those cultures change rapidly in species composition and locomotory traits as food wanes, and observe interesting behavior.
High quality videos also help a lot I think. I show my bio students all of the Blue Planet videos, e.g., any time I'm absent. Also, videos of cephalopod camouflage, surfers on breaking phosphorescent "red tide" waves, TED talks about emerging diseases, etc. The penis-fencing flatworm video is always popular and a great lesson in evolutionary biology ;) I have students do interactive global human population modelling, like the Geosim International Population Modeling applet on-line, and other ecology labs using real data to figure out modes of resource partitioning in real species assemblages, etc. I require a research paper in my bio class, and include a list of interesting ecological and environmental topics along with other biology topics. I try to bring in natural history, evolutionary biology and ecology all throughout my bio class, and some students get interested somewhere along the way. My 2 cents, Dave Whitacre Treasure Valley Math and Science Center Boise, Idaho
