Generally, a destructive act is exempt on shabbos (מקלקל). However, a Braisa says that חובל - making wounds and מבעיר- burning fires are exceptions and even in destructive manner one is liable. These must be exceptions bc there can never be any inherent positive outcome from wounds and burning. Even if one wants blood for their cat or ashes from the fire, the melocho itself is still inherently destructive. Acc to r shimon that מלאכה שאין צריכה לגופה פטור, we only look at melocho in its inherent purpose and we don’t take into account other objectives. It must be that חובל and מבעיר are exceptions and one is liable even when performing them destructively. However, acc to r Yehuda that מלאכה שאין צריכה לגופה חייב, melochos are broader and include other side benefits as well. It follows that חובל ומבעיר do not have to be exceptions and the cases of liability would be only if one had a usage for blood or ashes.

R shimon claims we see that חובל is an exception bc we require a special permit to do a Bris on Shabbos even though the extraction of blood is destructive. R Yehuda counters that the act is constructive bc it’s “fixing” the baby. Regarding העברה, r shimon proves it is an exception bc it’s forbidden to burn the adulterers Kohenes on Shabbos so we see destructive burning is forbidden. But r Yehuda counters that the issue there is the cooking of lead and not burning the girl.

Birds are usually considered trapped if they are in an enclosed house with a roof. But a unique bird called דרור that is very hard to control is trapped only if it’s inside a small closet area.

Animals are trapped even in a small garden that is enclosed. R Yehuda says they’re trapped only inside a home.

The definition of small garden is that the animal can be reached in a single lunge/the shadows from walls reach the other wall/does not have many corners

One isn’t liable for trapping an animal that can’t move- like a lame animal, old, or sick with fatigue, or grasshoppers when dew is on the ground. If the animal can move one is liable even if it has a fever, is blind, or is sleeping.

It’s a dispute, but he rabanan say one isn’t liable for trapping a species that isn’t normally trapped by people, like hornets and mosquitos.