The Kingdom of Mysore under the Wadeyar kings had a double headed eagle, Gandabherunda whose references are available in the Purana as their Emblem. Post independence too the Mysore state was enlarged in 1956 and renamed Karnataka in 1973, and the Gandabherunda continued as the official state emblem of Karnataka. It is used as the official emblem of the Karnataka state government because it is a symbol of strength. The symbol represents virtue of fighting the forces of destruction.
Gandabherunda in Purana:
The references if Gandabherunda can be found in Purana and various Sanskrit texts. And it symbolizes strength. The story of its origin goes as,
Mahavishnu took form of Narasimha and slayed Hiranyakashipu. Narasimha took ‘Ugra’ avatar to kill the demon. His anger was so strong that even after Lakshmidevi came and sat on his lap it was not pacified.
The gods and sages now panicked. Because this anger of Narasimha would burn the whole creation if not pacified. They all prayed to Shiva to mitigate the ferociousness of Narasimha. Shiva took Veerabhadra form and tried to fight Ugra Narasimha but he failed. Hence he took form of Sharabhasura, as he knew Vishnu will shed his Ugra Narasimha avatar and take some other form to defeat Sharabhasura.
Sharabhasura had the power of lion hence Vishnu took form as Gandabherunda bird whose food is lion. This bird form had hundred folds more power than Sharabhasura, so Vishnu could easily defeat Sharabha. In the course his Ugra Avatara was already shed hence Vishnu was now back to his Shantha roopa.
According to another version, demon Sharabhasura a Rakshasa king was tormenting his subjects.
He was a great devotee if Shiva and he had a boon that, he would not be killed by One headed gods, three headed Trimurti, or four headed Brahma, or five headed Adi Shakthi. Hence he thought himself to be invincible and continued his atrocities.
Hence Vishnu picked up a flaw in his boon and took Gandabherunda form which is a two headed bird, and slayed Sharabhasura.
Thus the bird became a symbolism of apex of Physical strength.
History of Gandabherunda as emblem:
Many if the ancient kings and emperors of ancient India either took it as state emblem or they adored themselves with titles comparing on self to Gandabherunda.
Hoysala Vishnuvardhana, Chalukya Vikramaditya, Yadava Singhana, Vijayanagara Krishnadevaraya, Achyutharaya compared themselves to Gandabherunda.
Apart from Purana, this bird appears for the first time in Takshashila manuscripts belonging to 6th century BC.
There is an ancient temple of 1047 AD at Ballgame in Shivamoga district of Karnataka, built by Chanmundaraya. He consecrated a Shiva named Gandabherundeshwara.
In front of the temple there is stone pillar at the top of which one can see sculpture of Gandabherunda,shown as swallowing demons. In Belur Chennakeshava temple, Gandabherunda sculpture slaying Sharabha can be seen.
Achyutharaya of vijayanagara had fascination to this bird, he even minted gold coin showing the bird flying upwards clasping an elephant in its claws.
Here elephant is a symbolic representation of Gajapathi kings from Orissa,whom vijayanagara rulers had defeated. Small rulers under them like Keladi and Mysore too adopted same as Royal emblem.
The Maharaja of Mysore used to bestow the highest honour of the state to accomplished persons in literature and culture by presenting them with precious stone studded with gold Gandabherunda medals.
When the government of Mysore Maharaja was merged into independent Indian union, the State of Karnataka came into existence. Naturally, the government opted for this emblem with very significant change.
Our national emblem of four lions was put on top of a Gandabherunda. Which signifies the powerful state being under one union government in solidarity.