Ecosystem surrounding me

The specific interactions that I observed was:
1, a mosquito and myself; A big mosquito (about 2inches long) was flying around me in my room. Because it was so big that I realized before I'm bitten by it.
2. a squirrel and a bird in the back yard: My host family has a bird, and because every time we refill the bird food in a container, we just throw some left over into the outside, I've captured some squirrel eating sunflower seeds in the bird food.

My observation in the back yard,
1.First of all, I had no idea how much junk were scattering all over in the backyard until I pay attention to what's really there. As you can see from the pictures, there are blue tarps, horses, cups, chairs and other junk. Those are apparently "straged" and setting there.

2.The major interaction that I captured was bird food. As I mentioned above, the birds share or compete among the bird food which could be Competition or Symbiosis. In a mean while, occasionally, some cats from the neighbors(foreigner) come to get the food. If the cats come and take the most of the food, the bird might not come.

3.Even if there are a big trampoline and jangle gym, we barley use them and also we don't take care of them and the backyard itself, so in fact, except the junk setting all over, it looked the backyard made a own community and I thought it might not too bad to just leave it as it is as supposed to taken care by the land owner who might use chemicals to "clean it up." Are weeding and sweeping just for better look? Can the species in the community make living easier?