When feral chicks are born they usually stay with their mother for about 10-12 weeks. Their bodies cannot produce all the heat they need, especially in temperate regions, so they will stay close to the mother especially at night. Often, the drake will stay in close contact with the brood for several weeks. The male will walk with the young during their normal travels in search for food, providing protection For the first few weeks of their lives, Muscovy duckling feed on grains, corn, grass, insects, and most anything that moves. Their mother instructs them at an early age how to feed. 
Raising Muscovy Ducklings
Under 3 weeks old (under 6 inches in length): In a small indoor cage with access to a heating pad or other form of heat (they are unable to generate their own body heat). Should not have access to water other than very shallow dish for drinking. A chick waterier is preferable and can be purchased online. This is very important; otherwise you may lose your ducklings to hypothermia or drowning. They are not water-proofed without their mother.
3-6 weeks old (between 6-9 inches in length): should be regulating their own body temperature; larger indoor or well protected outdoor cage. Introduce wading/baby pool once underbelly is fully-lined with feathers.
6-12 weeks old: house outdoors, safe, locked caging from predators (dogs, raccoons, etc). Use small gauge wire to wrap enclosure but never use chicken wire. Unlimited access to wading/baby pool to encourage "waterproofing"
12+ weeks: release; can fly and safely lift off water to escape snapping turtles. Is fearful of most humans and all pets. Has learned to seek out natural diet from soil and does not readily accept "handouts". Rate of survival is greatly increased by releasing groups of 2 or more juveniles together.
Ducklings under 3 weeks old: primary diet should solely consist of Egg Maker Crumbles mixed 1:1 with water (unmediated) available from the local Feed and Seed. Constant access to clean drinking water; "Chick Waterers" are ideal for this and cost $1-$3 at your local feed and seed. Can offer 10% dark greens and small insects. Anything else can lead to hypoglycemia (seizures from low blood sugar) or metabolic bone disease (not enough calcium, phosphorus, D3).
3-12 weeks old: In addition to earlier diet, allow "rooting" in yard and can also add Scratch Grains to diet (available from Feed and Seed or Food Lion).
The primary complaint in raising ducklings is mess and odor. The most efficient way to house ducklings indoors is in wire bottom cages so that spillage and droppings fall through to the news papered tray below. Wrap a sheet or towel to cover all sides of the cage except the very front. This will prevent food from being flung everywhere while they "dabble'. Offer a toweled area in the cage where they can rest as a group and stay warm, but replace the towel frequently. Avoid using hay or straw for substrate; it encourages bacterial growth and heavy odors. Use diluted bleach to clean caging; primarily to neutralize odors.
Never raise a single duckling alone. Muscovy ducks are domestic ducks and will imprint on humans, this includes sexual imprinting. Once mature, they will attempt to mate with humans (because they have been imprinted) following release. These ducks will be destroyed by Animal Control if complaints arise. Avoid this problem by raising at least two ducklings and allowing them to bond with one another instead of you (no matter how much they "peep" for attention). Handle them as little as possible and don't let them interact with your pets (otherwise they will think that all dogs and cats are friendly!). They will live longer after release if you raise them to understand that humans and pets are potential predators.
One of the most oft-asked questions I receive from new owners/enthusiasts is how to determine the gender of young Muscovy ducklings. A lot of people are familiar with the sex characteristics of the mallard derivatives, the curled tail feather, and the green sheen on the head, the hoarse, raspy quack of a drake or the loud boisterous quite audible quack of a duck. What some may not realize is that because Muscovy ducks are not a mallard derivative they do not possess these same characteristics.
From hatch until about 4 weeks of age there is really only one way of determining the gender of ducklings and that is by vent sexing them. This is something that isn't easily done if you're not familiar with the process. As it can hurt ducklings if done improperly, I won't provide directions here. It is best to find someone familiar with the process to show you how it is done in person.
It is at the 4 to 6 week mark that the drakelets begin out-growing ducklings and determining gender becomes easier. It takes a certain familiarity with the differences to be able to pick them out on the younger ducklings that are at that 4 to 6 week threshold, as the birds progress beyond this point it becomes considerably easier for the untrained and trained, for that matter, eye.
There are a few basic things that we are looking for when we attempt to identify sexes. My preference is to look at the bird in two ways, one is from the side, in profile, and the next is from above.
When looking at the ducklings in profile, drakelets are typically going to be longer front to back or bill to tail. I like to use the legs as the center point of reference for this. If you compare the length from the leg to the tip of the tail and the length from the leg to the bill on one duckling to that of another duckling, the difference will be noticeable on the different genders. Drakelets also have more pronounced and prominent breasts. They will have a long tail and their 'underline' will be fairly 'flat'. They have thick legs with a wide stance & larger feet. They will also begin to obtain their caruncling sooner. Another thing that helps is when comparing them to ducklets of the same age because they will not get their flight feathers as soon as ducklets will. Drakelets should have some red caruncling by the time their flight feathers grow in.
Ducklets on the other hand will remain 'petite' and feminine. They will have round, compact bodies. Their legs are thinner and their feet will be smaller. They won't have the breast that sticks out from their body; it will be close to the body. Ducklets get their caruncling later than drakelets however they will obtain their flight feathers sooner. Ducklets will be fully feathered by the time their caruncling begins to appear.
Do not release into an already over-populated area, otherwise local residents will "fix" the over-population problem themselves. Always take a fish net with you on releases in case a duck is not properly waterproofed and you need to rescue the drowning duck.
After finding a suitable nesting spot, the female will return each day to lay an egg. After she has finished laying all the eggs (12-30), she will remain on the nest fulltime to begin incubation. This will take approximately 34 days. The ducklings will all hatch on the same day, and then she will lead them to the safety of water. She will repeat this cycle up to three/four times per year.
Humane Domestic Duck Management
The goal is to humanely keep populations in check so that acts of cruelty against domestic ducks are reduced. Many people don't like Muscovy ducks and feel they have a negative impact on wild duck populations. When they outnumber wild populations, incidents of cruelty increase.
During the laying period (before incubation), the eggs are still dormant and should be vigorously shaken to cause the internal structure to change. Each shaken egg should be dated with a crayon the day it is shaken and returned to the nest. It can also be coated with vegetable oil. If the eggs are not returned to the nest, the female will mate again and start a new one. Do not shake two of the eggs so that the female will have young to care for, instead of starting another nest once she realizes that the eggs won't hatch. Keep the unshaken eggs on top of or away from any oiled eggs. The shaken eggs can be safely discarded one week after the female leaves the nest with her new ducklings; or 45 days after incubation began. Never shake an incubated egg; it has begun development and rather than rendering the egg infertile it will result in a deformed duckling.
Note: This information refers to domestic ducks only! It is a violation of federal law to disturb the eggs, nests, or raise ducklings of all wild ducks without first obtaining the necessary permits 
Muscovy Duckling Personality
By the age of about three months, the males are nearly twice as large as the females. I don't know if this is always the case. But, I've found that in younger Muscovy ducks, the feet of the males are often larger When raising Muscovy ducklings, keep in mind that they are very good climbers. Make sure that they will not burn themselves in the heat source should they climb the sides. Or, escape over the top if using an open brooder. 
Black Pied Muscovy Duckling:
Cairina moschata ducklings are mostly yellow with buff-brown markings on the tail and wings.
Atipico, dusky (a).
The recessive "a" allele in Muscovy ducks is called the atipico or dusky variant. It's most notable in ducklings in that it removes the yellow, leaving a solid colored ducklings.
Atipico with Yellow Bibs:
Some Muscovy ducklings are Atipico, but have a yellow bib.
Blue Muscovy Duckling:
Some domesticated ducklings are dark grey with blue eyes.
White Muscovy Ducklings:
Some ducklings are solid pale yellow with dark markings on the head or tail. 
Ducks may be orphaned for the following reasons: late hatching, stray or too weak during walk back to water, injured, human interference. Attempting to pair a singular duckling back with its mother is not recommended. It will be killed if it is paired with the wrong mother. It cannot survive on its own without its mother's warmth and protection. Lone ducklings quickly fall prey to other ducks, turtles, and egrets/herons.
Orphaned ducklings should be rehabilitated with ducklings of similar age and size. Ducklings are also extremely fragile, easily chilled and can be injured due to over handling. An improper diet can rapidly lead to hypoglycemia. A very young duckling that is staggering or appears "drunk" is hypoglycemic and will die unless it is provided with some source of sugar. Dextrose or a small amount of table sugar mixed with water can be smeared onto the duckling's tongue. It should respond to the sugar within 20-30 minutes. It should immediately be provided with the correct diet to prevent the condition from occurring again. . Muscovy ducklings are considered domestic ducks and can be reared by individuals without permits.
If the nest is in potentially dangerous location:
Guess when the eggs will hatch based on observations. How long has the female been seen on her nest fulltime? It is important to have a general idea of when the ducklings will hatch.
If the nest is in a residential area
Mom and ducklings can be chaperoned on their walk back to the water if there is a concern about vehicular traffic in the neighborhood. Use the guesstimated date to plan for this walk. Also get the assistance of a couple of neighbors, but discourage bringing children along because the mother duck may view them as a potential predator.
If the nest is separated from the water body by a major road
Find out what body of water the female utilizes. Try to observe her as she leaves the nest for her early morning or late evening feedings. If intervention is needed, taking mom and ducklings to the wrong water body will only make matters worse. In other words, you cannot guess (you must know where she is headed). Once she begins incubating, the female can be seen flying to the water source where her mate is waiting (once or twice a day - early morning or late afternoon), for food and water. The water body is usually within 200 yards of the nest site. Even if the exact location is not known, the direction which she usually heads is needed.
Based on the "guesstimate" of when the eggs should hatch, approximately one week before the due date erect a 12-24 inch tall wire or mess fence around the nesting site. The openings should not be larger than 1 inch, otherwise the ducklings can escape, but the diameter should be wide enough to allow mom to fly in and out. This fence will prevent a mom from moving the ducklings until assistance can be provided. However, this only be done if the nest is in a location where someone is observing it daily and the move can occur on the same day (otherwise the ducklings could die from dehydration, starvation, or predation).
Once the ducklings hatch, they can be moved into an escape-proof pet carrier and walked to the water body. Only one person should do the "walk"; a crowd of people or too much activity will deter mom from staying nearby. Mom must be able to hear and preferably see the ducklings throughout the move so she does not get too discouraged and abandons them. If mom flies away, set the carrier down until she returns (usually within a matter of minutes) then resume the "walk". Once you arrive at the water body, set the carrier down then back away and let mom and babies vocalize with one another for a minute or two. If you open the carrier before they have identified their mom, they will scatter.
If a mom and ducklings are already on the move and are headed for imminent danger:
Decide whether it is possible to delay the move until traffic volume is lower and they can be chaperoned across the street, or whether they will need to be captured and relocated to the other side of the street.
Create a barrier to prevent mom from attempting to cross the street (human deterrence, sheets, fencing, etc) and encourage mom to return to the nesting site (or someplace that the babies can be easily captured).
Ducks and ducklings remain calmer when humans move in slow, deliberate moves. To herd the ducklings to an area for easier capture, volunteers should form a semi-circle around the ducklings (maintain a 6-12 foot buffer) and slowly walk the ducklings towards the preferred area. Use movements similar to guiding a plane in for a landing; long, slow sweeps with your arms works best. Mom will stay with the ducklings until she feels threatened, then she will briefly fly away. Once the ducklings are cornered, use the bed sheet to create a makeshift fence and transfer the ducklings to the pet carrier. Moving mom with the babies is preferable, but impossible if she is capable of flight. Do not begin the move until mom has returned.
It is important to know what direction mom was originally headed. Relocating her to the wrong body of water will leave her and the ducklings without the protection of the male. She may even attempt to move them to the proper location, again placing herself and the ducklings in danger.
Ducklings in the Pool
If ducklings get trapped in a pool, the quickest method to get them all safely out and back with mom is to build them a small ramp to help them over the edge. It is imperative that this be done as quickly as possibly because the ducklings cannot go without food too long and will soon get weak and cold. All filtration systems should be turned off until the ducklings are safely out of the pool. The easiest ramp to build is made from a piece of Styrofoam and a towel. Use a very large bath towel and the lid of a Styrofoam cooler (available at most convenience stores). Wet the towel (to increase its weight) then float the Styrofoam lid at the edge of the pool and drape half of the wet towel over the Styrofoam lid. The other half of the towel should be draped over the edge of the pool. It can be weighted down with a brick if needed.
The Styrofoam will serve as a floating dock that the ducklings can jump onto. The towel will allow them to make their way over the edge of the pool. Imagine how happy those ducks are; you were nice enough to provide them with a wonderful pool, surrounded by wonderful landscaping and safely enclosed from predators. It just didn't occur to them that you didn't do it for them. They've learned from repeated visits that it is a safe place to be. Then, after you chased them away a few times, they continue to return but they learned it is only safe when humans aren't nearby. You'll have to condition them to understand that it just isn't safe anymore. 
THE MIRACLE OF IMPRINTING
There is an ability limited to birds alone that makes geese, the first, and ducks, the second, most natural animal companions to humans. That ability, which is one of the strongest forces in nature, is the imprint. No one understands exactly what happens inside a bird’s brain when imprinting occurs, but the results are unmistakable. The imprint is strongest in geese and almost as strong in ducks.
Basically, a duckling or gosling knows that it is the same species as whatever living creature larger than itself it sees upon hatching or shortly thereafter. I said, knows. It doesn’t think it is, it doesn’t use the creature for a replacement until it finds its own species, it doesn’t pretend to be that species; it is that species in its mind. The imprint is so strong in birds that when one is raising a wild baby bird to be returned to wild, it must be fed with hand puppets of its own species in order to prevent it from imprinting on a human instead. So, if you want a bird to live with its own species, you avoid having it imprint on a human, but if you want a bird to live with humans, you make sure it does imprint on a Human. It imprints on the species right away, but doesn’t recognize an individual face for about a week even though it may recognize a voice.
I’m sure a lot of you hollered when you read that geese and ducks are the most natural companions of man. What about dogs and cats? No matter whether you raise a dog or cat from the instant it is born, it will always know it is a dog or a cat. We have to train, control and confine them to keep them from going off with their own or following their natural instincts to roam and hunt. They definitely form bonds with us, but they have strong ties to their own species. An imprinted duck or goose doesn’t. Unless it is raised with other ducklings and goslings, because not only do ducks and geese imprint on a parent(s), they imprint on Sibling!
This is where imprinting becomes complicated and differences between ducks and geese become apparent. I’ll try to simplify it. At birth, if a duckling sees a duck, so the duckling knows it’s a duck. When Mom is a duck, all ducklings love Mom. If the duckling sees other ducklings, the duckling will know that it is also a duckling sibling, when the ducklings grow to be adult ducks, they don’t need Mom anymore. The Duck now like other ducks, and the duck will mate with other ducks. Mom is now just another duck. Duck may love Mom, may not.
Now if the duckling sees a human at birth, the duckling thinks it is human. If Mom is human, and the duckling doesn’t see other duckling, the duckling perceives it’s self as only human. The duckling loves and needs Mom. The duckling eventually grows to be duck, and the duck likes humans. The duck doesn’t mate with other ducks, perceiving it's self as human. Duck loves Mom best.
Personalities, circumstances, raising, etc. can, of course, have an effect on the above outcomes, but generally speaking that's how it works. An injured bird that is rescued, for instance, may be imprinted on its own species, but may bond very closely with its rescuer. A duckling or gosling that has been raised in the house and is firmly imprinted on its human Mom and Dad may become reserved or even hostile if it is expected to live outside on its own or with other geese after it is physically grown. Geese don't mature until they are 3 - 4 years old, so they expect to stay with their parents for at least a year or two and have them close by after that. Ducks are not mature until 2 years of age.