What is the predicted effect of bird presence on the survivorship or biomass of the plants? (Hint: if this question leaves you puzzled, it may help to think about feeding time. If there were no birds, would more or less plant tissue be eaten by grasshoppers?)
1. more birds results in decreased biomass
2. more birds results in increased biomass
3. fewer birds results in increased plant biomass

2. more birds results in increased biomass

Explanation:

Since  birds mostly feed on insects. The increase in number of birds will cause a decrease in insect population.

Now if we consider plant eating insects, the increase in plant eating insect population will result in decrease in biomass of plants because they eat up the plant tissues.

Now relating the above situation we can conclude that if the population of bird increase, they will feed on more and more insects and thus the population of insect will decrease. and in turn, the survivorship or biomass of plants will also increase.