What is the tone in the poem " In Reference to Her Children"?

There is no one word to describe the poem's tone because Bradstreet uses tonal shift to advance her theme.  In the beginning of the poem, the mother bird speaks of each of her brood (children) and how many of them have flown the nest to make lives for themselves.  For this part of the poem, a good tonal word is "nostalgic" and "possessive."  While the mother bird is proud of her children and their accomplishments, she misses the time when she was in control of them and they were dependent upon her.  She does also come across as being rather possessive.  As some of her children leave the nest, she yearns for their return and finally gets them to come closer to home.  She, like most humans, is experiencing "empty nest" syndrome.  For most of her life, she has been busy at being a mother, but now she doesn't feel needed as she was when her children were young.

In the middle of the poem, as Bradstreet begins to list the lessons that the mother tried to instill in her children, especially about the dangers of their environment, she demonstrates a proud and concerned tone.  She worries whether her children will heed her warnings, but she is also proud of all that she did for them and hopes that they realize what she has endured for them.  She says,

Great was my pain when I you bred,
Great was my care when I you fed.
Long did I keep you soft and warm
And with my wings kept off all harm.

Finally, in the last lines of the poem, the speaker actually shifts from a narrative style to a sermonic one.  Instead of telling an unknown audience of her children and her life as their mother, she directly addresses her children.  At this point, her tone is didactic--she hopes to impart one more lesson to her children.  Even though much of the rest of the poem comes across as a mother longing for former days, the speaker's lesson is hopeful and positive.  She mentions where she will go when she passes from this earth and then tells her children,

Farewell, my birds, farewell, adieu,
I happy am, if well with you. 

She wants her children to know that she is satisfied with her life and that she will be happy as long as they are safe and healthy.