4. I (feed) ________ birds at the park yesterday. I (feed) ________ birds at the park every day since I (lose) ________ my job.

The first blank needs the past simple because of 'yesterday', so the past tense of 'feed' is 'fed'. The second blank needs a present perfect because of 'since I lost my job', which means that the action continues to this present. We also need to find the past simple of 'lose' because 'since' needs a past action for the time. So, we have to use the past simple which is 'lost'. Therefore, the answer is: 4. I fed birds at the park yesterday. I have fed birds at the park every day since I lost my job.