I agree. It's pretty cold/bad time of year to be ordering just a few ducklings, so there's going to be a risk shipping replacements. If someone wants ducklings or chicks in winter I think they need to be aware it's cold and stressful and some might not make it. If you don't want to take the risk wait until spring.You seriously need to call them and not post random what ifs online. Its the only way you will get direct and fast answers from the business itself.
As John said above, if you had 1 duckling die in your order, they are happy to ship a new one, BUT they have to send a second as traveling warmth companion. If 1 of those 2 happen to pass away you still got your replacement you were owed and now are owed nothing further.
Its a risk associated with shipping and as the buyer you have to be aware of that and agree to take the risk too.