Under the Immigration Ordinance, a person who belongs to one of the following categories of persons is a permanent resident of the HKSAR and enjoys the Right of Abode (ROA) in the HKSAR :
a. A Chinese citizen born in Hong Kong before or after the establishment of the HKSAR
b. A Chinese citizen who has ordinarily resided in Hong Kong for a continuous period of not less than seven years before or after the establishment of the HKSAR.
c. A person of Chinese nationality born outside Hong Kong before or after the establishment of the Hong Kong Special Administrative Region to a parent who, at the time of birth of that person, was a Chinese citizen falling within category (a) or (b).
- A person's ROA by virtue of his being a permanent resident of the HKSAR under this category can only be exercised upon the establishment of his status as such a permanent resident by his holding of -
(a) a valid travel document issued to him and of a valid certificate of entitlement also issued to him and affixed to such travel document;
(b) a valid HKSAR passport issued to him; or
(c) a valid permanent identity card issued to him.
So, as you have your birth certificate to prove you are born in HK, you can apply for HKID card.
For application of HKID card, you may visit
http://www.immd.gov.hk/ehtml/hkid.htm#application