Seagulls will normally fly around your raft before swooping down to eat any crops or plants that may be growing. It is hence necessary to protect your gardens or else the Seagulls will not leave anything for you to consume.
There are a couple of ways to defend your raft against Seagulls. The following guide will show you how.
How To Protect Your Crops Against Seagulls
Seagulls always fly in pairs and the number is the same no matter what difficulty you are playing in. They also only target small crops and will never go after any large plant that you are growing on your raft.
When they land to start eating your crops, you have around 15 seconds to make them leave before the crop is completely gone.
The first and obvious way to protect your crops is to kill Seagulls. In normal difficulty, you can use a Metal Spear or a Basic Bow to one-shot a Seagull. You can also just throw stones at them. In hard difficulty though, a Seagull will require two hits to die.
You can craft a Metal Spear using 6x Plank, 2x Rope, 2x Metal Ingot, and 1x Bolt. If that is too bothersome, you can craft a Basic Bow using 6x Plank, 4x Rope, 2x Vine Goo, and 1x Bolt. If you are opting for the cheap way out, just find Stones on the ocean floors near islands.
Take note that Raft spawns a Seagull after every 7-8 minutes. Hence, trying to kill all of them after every few minutes is likely going to get frustrating. You will need a more permanent solution.
Build A Scarecrow
What you need is a decoy to protect your crops. You will have to build a Scarecrow using 5x Plank, 3x Palm Leaf, 3x Nail, and 3x Plastic.
Planks and Palm Leaves can be found by pulling in flotsam or Barrels using either a Hook or a Simple Collection Net. Nails can be crafted using 2x Scrap or found inside Loot Boxes. Plastic, likewise, can be found within flotsam, Barrels, and Loot Boxes.
Seagulls will go after the Scarecrow instead of any crop. The only problem is that a Scarecrow has only three hit points and if there are two Seagulls, the second one will likely go after your crops.
Hence, you will need several Scarecrows to keep all Seagulls distracted. Scarecrows only protect crops within a 6-meter radius. Once a Scarecrow is under attack, you will have enough time to kill or scare them away.
Build A Greenhouse
While the first two methods of protecting your crops against Seagull attacks were only temporary, building a Greenhouse will offer a more permanent and robust solution.
Greenhouses are wooden, roofed structures with or without windows. You can put your Small and Medium Crop Plots inside and forget about Seagulls.
However, make sure to not place anything above or near your Greenhouses such as an Old Shoe, Grass Plots, and Crop Plots. If you do, there is a chance that the Seagulls will clip into your Greenhouse while attacking the crops above or near it.