In an environment in which insect populations are decreasing, which bird, small insect eater, cactus eater, seed eater, bud, leaf and fruit eater and what bids population might also decrease over time?why?

The population of insect eater birds are decreasing due unavailability of food.

Explanation:

If the population of insects in an ecosystem decreases, so the organisms which feed on them i. e. insect eater birds also decreases and die due to hunger. In an ecosystem, every organism is the food of other organism, if one organism is eliminated or reduced in population, then the other organisms will also be affected.

for  example, forests have higher evapotranspiration than other ecosystems,  such  as grasslands, because of their deeper roots and greater leaf area. thus forests have a net moistening effect on the atmosphere and become a moisture source for downwind ecosystems.

try using substitution:

x + y - 6 = x - y. (i'm not giving you the exact answer). since 0 = x - y, then sub 0 in the equation with x - y. combine your like terms, and then use inverse operations, and you'll have your answer.

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