Determining if a rabbit is pregnant can be a bit challenging as the signs may not be obvious until later in the pregnancy. However, here are some common signs that can indicate pregnancy in rabbits:

1. Nest building: Pregnant rabbits may start exhibiting nesting behavior by collecting hay or other materials to create a nest. They may pull fur from their body to line the nest.

2. Weight gain: Pregnant rabbits will gradually gain weight as the pregnancy progresses. However, keep in mind that weight gain can also be due to other factors such as overfeeding or a medical condition, so it is not a definitive sign of pregnancy.

3. Changes in appetite: Some pregnant rabbits may experience changes in appetite. They may eat less or exhibit picky eating behavior. However, appetite changes can vary among rabbits, so it is not a reliable indicator on its own.

4. Swollen abdomen: As the pregnancy progresses, a pregnant rabbit's abdomen may become visibly enlarged. However, this may be difficult to observe in some rabbits, especially those with a thick or long coat.

5. Nipple development: Female rabbits that are pregnant may have enlarged and more prominent nipples. This is usually more noticeable in the later stages of pregnancy.

It is important to note that these signs can also be associated with other conditions or false pregnancies. If you suspect that your rabbit may be pregnant, it is recommended to consult a veterinarian for a proper diagnosis. A veterinarian can perform a physical examination or imaging techniques, such as ultrasound, to confirm pregnancy.

Remember, rabbits have a short gestation period of about 28-32 days, so if you suspect your rabbit may be pregnant, monitoring for these signs and seeking veterinary advice is essential.