In studying J.P. Clarke's poem, "Abiku," I first needed to know the meaning of the title.
The Encarta World Dictionary defines "abiku" as:
[a] West Africa reincarnated being: a spirit in the form of a child who must repeatedly die and be reborn
With this in mind, it might seem that Clarke is speaking to the dead spirit, welcoming it. However, this definition may be used in the poem metaphorically.
The setting is a home—the speaker's home. He encourages the spirit to go where it must:
Coming and going these several seasons,
Do stay out on the baobab tree,
Follow where you please your kindred spirits
If indoors is not enough for you...
...but even with this said, the speaker goes on to describe the abode. He is honest in his assessment of the physical structure. The thatched roof leaks when the rain is hard ("when flood brim the banks"), and bats and owls break through the eaves at night by ripping into the roof's covering. When the harmattan...
a dust-laden wind on the Atlantic coast of Africa in some seasons...
...arrives, the chance is much greater of the walls going up in smoke and fire because the blaze used to dry the fish whips about with the gusts of wind.
The speaker describes a humble home that does not offer much in the way of material substance: it struggles to survive the elements and nature's creatures. However, within these walls, there are those who will welcome the "child." The speaker may well be addressing a literal "child," one that has lost home and family and is being invited to stay. (And if not, he is still extending his invitation—but to a ghostly child that forever wanders, offering it a place where it might rest.)
I would suggest (my interpretation) that the theme of the poem is home: there is always a place for you at our fire, however humble. The setting is presented in such a way that the invitation is a modest one, but genuine—no promise is made of great comfort or lavish appointments. But the speaker is suggesting that the willing, kind and welcoming people that live within, however poor and fragile the house may be, offer not material substance as much as emotional substance: support, concern and love. In these things, they have a great supply—
For..."many more mouths gladden the heart."