As humans, we expect everything we see and experience to fit in a particular mold. My readers often tell me that my alien characters are not behaving in a logical fashion, when in reality they're not behaving in a way that a human would consider logical. Logic is in the eye of the beholder.
I once had a very interesting conversation with a young man who insisted that a preference for blue and pink was built in to the genders. The fact that I, as a female, do not care for pink, was totally incomprehensible to him. He concluded that I was lying about my color preferences. To him the connection between gender and color (a social construct) made perfect sense and was entirely logical.
Many other examples point out that our logic isn't really logical when it's put up against something different, but as readers we still insist on using our own standards to measure other cultures.
When readers see an "alien" they subconsciously expect that this thing looks different but will behave in familiar ways simply because it's sentient (Ironically, we expect the same in regards to people from other cultures, but that's a rant for another time). That is not always the case, and getting past those expectations is a waiting game. Break your readers' expectations too soon, you risk losing them, and once lost they will not be brought back easily.
When building an alien culture, it's important to initally present aspects of alien culture that seem to mimic humanity, while gradually building up those aspects that separate this culture from the humans around them.
One of my favorite "alien" books is Remnant Population by Elizabeth Moon. She handles the alien culture question by removing the human culture and gradually shifting the one remaining human's outlook until it closely matches the alien culture. Since the reader has already accepted the human character's excentricities, the aliens' behavior seems normal and acceptable in contrast. She increases this by making us dislike the human culture that Ophelia came from.
She takes the time to establish this fact, and only gradually does she differentiate between the two cultures. Then at the end wham bam we discover that everything we thought we knew about the culture is in fact wrong.
A few aspects of human culture are easily translated into an alien environment. Curiosity, fear or worry, sometimes love or friendship. If nothing else, these can be used as a base to build on, one which will allow your readers to connect with your aliens rather than dismissing them and their behavior as "illogical."