Have you ever seen these tropical birds? If you haven't, it's too late. They are as dead now as the dodo bird. Species extinction has always taken place, of course, but many believe that the rate of extinction has risen thousandfold from the early figures of one to two species out of a million each year. The most pessimistic forecasts imply that in fifty years time we may lose a quarter to a half of all now-existing species. Much of this increase is due to human activity.
This planet might become quite a lonely place for the humans. That has its good sides, too. More space for shopping malls and new housing developments, more relaxing camping holidays with no bears or wolves to worry about, more space for industrial agriculture, which will be needed to feed all the people who move into the new housing developments and shop in the new shopping malls. But it will be lonely, especially for the children who can no longer read about the tigers and the rhinoceri or the elephants.
It may also be bad for adults, even those who hate all wildlife as vermin. The species on this earth are interlinked and each extinction unravels a small whole into the overall fabric. Some of those holes will be at unimportant places in the weave, and will not matter much for the overall design. Others, however, might break the very foundation threads of our existence and directly threaten the survival of everything, including homo sapiens.
Consider the humble bee. It stings, true, but it also makes honey. If it went extinct we'd lose both of these. But we might also lose apples, at least in some areas, as the bee is the major pollinator of apple trees. The bees may be only a tiny thread in the overall tapestry, but their loss would leave a big hole behind.
I don't know what will unravel because of the extinction of the Mariana Mallard and the Guam Broadbill, but there's bound to be something. If nothing else, the loss of their beauty and wonder is a loss for ever.