According to the title narration of the cartoon Count Duckula (1988),
Castle Duckula, home for many centuries to a dreadful dynasty of vicious vampire ducks – The Counts of Duckula. Legend has it that these 'fowl' beings can be destroyed by a stake through the heart or exposure to sunlight. This does not suffice however, for they may be brought back to life by means of a secret rite that can be performed once a century, when the moon is in Eighth House of Aquarius.... The latest reincarnation did not run according to plan....
We then are shown that the "current" incarnation of Count Duckula is very un-vampire-like. Due to substitution of tomato ketchup for blood in the reincarnation ritual, the new count is a vegetarian who has little interest in vampire things and can't be bothered to suck anyone's blood.
This narration strongly implies that the immediate predecessor of the current Count Duckula was, in fact, a traditional vampire who most likely met his end in the late 19th century through one of the listed methods.
Is it ever established in the series or in supporting materials how exactly the previous Duckula met his end? Was he staked through the heart? Was he destroyed by sunlight?
In response to comments, whether or not each incarnation is epistemologically the same duck as before is not part of the question. If you feel that there is only a single Duckula and each incarnation is just the same character in a new body, you can interpret the question as "How did the previous incarnation of Duckula meet his end?".
Also in response to comments, this question is not intended to delve into a discussion on what it means for an undead creature to die. For the purpose of this question, assume that any event that requires the vampire to be resurrected by the once-in-a-century ritual (e.g. being staked through the heart or being exposed to sunlight) qualifies as "meeting his end". If specific episodes of the series establish additional ways for an incarnation to be offed (e.g. fire, acid, extreme bowel blockage, etc.), then those methods count for the purposes of this question.