Mayapple. I see many immature Mayapple fruits on numerous plants throughout the park, now.
Yellow Warbler. A Yellow Warbler against a blue sky is something I always find attractive!
Mallard. Three mallards are now hanging around the creek on a fairly consistent basis. There is a male-female pair and this male shown here. It seems to have the upper hand in the situation, for it is not uncommon for this drake to chase the male-female pair away when they get too close.
Red-winged Blackbird. There are a few females, like the one shown here, that are pretty consistently in the foliage along Trout Run Trail by the creek. There is a swampy area nearby that rings with the fairly continuous calls of Red-winged Blackbirds. Perhaps that is their home base.
Northern Rough-winged Swallow. When the insects were hatching along the creek in the first part of May (that activity seems to have died down for the moment), the mixed swallow feeding flock continued to grow in size. After Tree Swallows, Chimney Swifts, and Barn Swallows arrived, this Northern Rough-winged Swallow snuck in at the tail end of the insect hatching window. The swallow flock has currently disappeared, though this morning the trees along the creek were filled with Cedar Waxwings, which can put on their own impressive "flycatching" show.
Eastern Kingbird. This is the first kingbird I have seen this year and may be a "scout" with the main population passing through later. (I've not seen signs of them nesting in the park in previous years.) I had 14 sightings of kingbirds in Oatka Creek Park last year, with a peak in July, so maybe they were nesting at least nearby?
Yellow Warbler scanning the skies for potential predators. A Sharp-shinned Hawk might be the most likely predator, though Red-tailed Hawks are being mobbed and attacked by crows and Red-winged Blackbirds with increasing frequency of late.
Indigo Bunting. This bird was skittish and, perhaps, is a nonbreeding male due to the splotches in its plumage. However, one has to be careful with Indigo Bunting feathers, as their color comes from their feathers refracting and reflecting blue light, similar to the reason why the sky is blue. They have no blue plumage in their feathers. Cornell's All About Bird http://www.allaboutbirds.org/guide/Indigo_Bunting/lifehistory suggests that this is true for all blue birds. All subsequent Indigo Buntings I have seen are pure blue and not afraid to be seen as they define and defend nesting territories in the park.
Marsh-pea. These small flowers may have bloomed a couple of weeks early this year. And now some tech-talk: The camera absolutely refused to focus on these magenta flowers and, instead, would only focus on the surrounding green foliage. Green and magenta are complementary colors in terms of the spectral distribution of light. It looks like the autofocus algorithm in my camera was using only the green channel of the image to determine focus. Since magenta basically does not appear in the green channel, there was nothing from the flowers for the camera to "lock on to". I ended up having to place my hand next to the flowers, focusing on my hand and then recomposing the shot without changing focus.