Isle of Berk Addons is a collection of small additions to and QOL tweaks for the Isle of Berk mod. 
Dragon Whistle
Are you tired of chasing down rambunctious dragons who stay just out of reach of your commands? Chase no longer! The IoBA dragon whistle can issue commands from a distance, allowing you to direct your dragons from a distance. Dragons can be told to sit, follow, or wander using the whistle. Whistle commands can also be directed only at a specific species of dragon, and the whistle's range can be customized via the IoBA config. Selected command, species, and range are visible in the whistle's tooltip (and appear onscreen above the hotbar when first selected).
Right clicking the whistle will issue its current command. Left clicking it on a block will cycle its command between sit, stay, and follow. Sneak right clicking on a block next to a dragon will cycle between all dragons or that particular dragon's species-- and, in the case of night furies, light furies, and night lights, a third option which allows you to command all three related species.
By default, the dragon whistle is crafted using two sticks placed diagonally.
Advanced Spawn Management (Supports Modded Biomes)
At this time, a bug in Isle of Berk prevents dragons from spawning in (most) modded biomes, even when those biomes are added to the spawn list. To compensate for this, I've temporarily added an advanced spawn config (iobaddons-spawns.json) to the mod. These spawns are disabled by default to prevent them from overlapping with IoB's default spawns, and their config file will not appear until they have been toggled on via the main mod config. Turning on the IoBA spawn system will allow you to use the json based system to add new spawns for dragons, including spawns for modded biomes (using their biome id). It is recommended but not required that you remove all spawns from the default IoB config if you enable the IoBA spawn system, as the default spawns are a 1:1 mirror of the defaults set by IoB, which may cause dragons to spawn with too high a frequency.
This feature may eventually be removed if IoB includes built-in support for modded biomes.
Disclaimer
Isle of Berk Addons is independently created and isn't affiliated with the Isle of Berk team. To the best extent of my knowledge, it complies with the "custom assets" clause in IoB's permissions. At this time, IoBA does not add any dragons of its own, so all dragons influenced by this mod belong to IoB. IoBA is also not affiliated with Dreamworks animation or the official How to Train Your Dragon franchise.
Promotional Screenshots taken using Oh the Biomes You'll Go and Complementary Shaders. Featured dragons are, of course, from Isle of Berk.