What is This? (1 Viewer)

What is this? It is over topping trees at a good site for Blue-winged Warblers in South York County PA. No Blue-winged.

The flowers are a species of honeysuckle Lonicera, almost certainly one of the invasive Asian species. Although a serious problem weed in US forests, I'd doubt it is responsible for the decline of BWWarblers, though. For explaining that, I'd be looking more to habitat degradation from pesticide drift (insects declining not just in sprayed farmland, but in the whole environment), deforestation on their migration routes (can they find highly important stopovers to fatten up well enough for crossing the Caribbean??) and wintering areas, global warming (upsetting timing of maximum insect productivity away from nesting periods), and nest competition from Cowbird chicks.

The 5-pointed leaves (lower middle) are Virginia Creeper Parthenocissus quinquefolia, native in your area.

The pinnate leaves (top left) might be Tree-of-heaven Ailanthus altissima, but pic isn't large enough to be certain. If it is, that's another problem invasive in N America.