Several times the passage mentions birds, horses and cattle, however they are in odd situations. The flock of birds in ‘How Cuchulainn was begotten’ were seen to destroy the human character’s land and were hooked together by silver chains. The foals were supposed to raise young Cuchulainn and herds of cattle are referenced often through out all of the sections. Based upon these references, how are animals viewed through the eyes of the Tain characters? Do they treat them with respect or as a force to be dominated? Feel free to bring in your own textual references other than the ones mentioned above.
I think in that particular passage, the animals serve as omens surrounding the birth of Cúchulainn. The birds descend onto the pain and eat the crops of the Ulster men, signaling that something great is about to happen that will affect not only all of them, but the whole region. The concurrent birth of the twin foals serves to underline Cúchulainn’s specialness as well, suggesting that he will be twice as great as any other hero of Ulster. In this sense, nature either serves as having a unique perspective as witness to fate, or as fate’s emissary. Either way, nature is seen as part of a larger force that acts upon human lives, over which humans have little control over. The fact that the birds carry silver chains seems to support this as well, since chains are things that bind and restrict. This seems to fit a common medieval view that nature is set against or is more powerful than human will and human culture.
Animals and nature in the táin seem to be a product of the supernatural. As you said they all show up in mostly “strange” circumstances, and therefore most of the nature we see only really exists in the context of the supernatural. However, I think the Irish viewed the supernatural as something beyond their control and even something that controlled them, so this is not to say that they view nature as something to be dominated. Instead, it seems that nature, being intertwined with the supernatural, becomes an even more dominating, almost sentient force. I think it is interesting to note the difference in this implication to that of medieval English/French interpretations which saw nature as an every day part of life.