(In this unique article Kashmir Csaky describes the intricate details involved in artificially incubating Hyacinth Macaw chicks, and also why human assistance may be necessary to help with the hatch...)
I held a glistening white egg in the palm of my hand, gently, carefully peeling away tiny bits of eggshell. Macaw eggs look like big beautiful, oval pearls, they have an almost iridescent smooth surface - not the rough, dry texture of a chicken egg. The warm egg was pulsating in my hand as the chick attempted to break free of a home that had now become a prison. The chick's peeping was strong and determined. Yet, like most Hyacinths, this chick needed assistance to successfully hatch.
When I am asked why I choose to artificially incubate certain Hyacinth eggs, I find myself explaining that few Hyacinth chicks are able to hatch in the nest. Hens gain experience with time and can learn to hatch difficult eggs. However, if a hen suffers repeated failures during one breeding season she will become depressed and anxious. At this point it is more compassionate to remove the eggs than to allow her to suffer another failure. Yet, artificially incubating Hyacinth eggs is not for the inexperienced aviculturist. This article is not a primer on incubation techniques; it is intended for aviculturists with experience who would like more information on incubating these difficult eggs.
From the time a bird egg is laid until drawdown it should lose about 16 per cent of its weight. This is the optimum weight loss for most species. When the humidity is set on an incubator it is assumed that the egg will lose the necessary weight if the setting is correct. However, even in a dry incubator most Hyacinth eggs will not approach this ideal weight loss. So they must be weighed at the same time every day and calculations made to establish how much weight an egg needs to lose to reach the target weight. Accurate daily record keeping is vital, since this will indicate if it is progressing well and aid in predicting what changes will be required in order to have a live healthy hatch.
Determining Target Weight Loss
If artificial incubation begins on the day an egg is laid, predicting the target weight loss is easy. The ideal weight loss should be 16 per cent of the lay weight, so multiply the lay weight by 0.16. To determine the desired daily weight loss, divide the computed weight loss by the number of days till internal pip, about 25 to 26 days for Hyacinth eggs.
This data is based on egg 1-1-95
Lay weight = 32.25 grams
Target weight loss = (32.25) x (0.16) = 5.16 grams
Desired daily weight loss = 5.16 / 25 = 0.21 grams per day
When artificial incubation begins several days after the egg is laid then determining lay weight is more difficult. It is possible to estimate the weight of the egg by using a coefficient - fudge factor - to modify the formula for the weight of a cylindrical object. This coefficient is different for every species to allow for variations in the densities of the contents of the egg and egg geometry. The species specific coefficients are determined empirically. Species specific coefficient for a variety of psittacine eggs can be found in Parrot Incubation Procedures, by Rick Jordan. Although the species specific coefficient for Hyacinths was based on a small sample, I have found that Rick Jordan's calculations closely correspond to the data obtained from my Hyacinth eggs.
Using vernier or digital calipers measure the length and width of the egg in millimeters. To estimate the lay weight of the egg, first multiply the length times the square of the width, then multiply this number by 0.0005460, the species specific coefficient for Hyacinth eggs.
Also based on egg 1-1-95
Length = 47.4 mm
Width = 35.0 mm
Species specific coefficient = 0.0005460
Estimated lay weight = (0.0005460) x (47.4) x (35.0)2 = 31.7 grams
Note that in this case the estimated weight is about two per cent (0.55 grams) below the actual lay weight. The correspondence in some cases was even better.
The target weight loss for Hyacinth eggs has been noted at 17 per cent to 20 per cent of the lay weight. In my experience this is high. The usual 16 per cent weight loss can be applied to Hyacinth eggs. I have incubated many eggs that lost 14 per cent of their weight. The hatches were not particularly difficult or wet and the chicks were healthy.
Controlling Weight loss
It is prudent to take small steps in correcting a problem, since anything done to the egg is irreversible. Unless over corrections are made, too great a weight loss is seldom a problem with Hyacinth eggs and will not be discussed here, except to say that by increasing the humidity excessive weight loss can be controlled. It is easier to correct daily weight losses that are slightly too high than it is to correct daily weight losses that are too low. Check the weight six and 12 hours after any corrections are made. By checking twice in a 12 hour period you should be able to tell how effective your efforts have been and how fast the egg is losing weight.
When the daily weight loss is substantially below the expected value and the total weight loss is less than desired, it is possible to increase the evaporation of fluids in the egg through the porous shell by washing the cuticle off the egg. This will hasten the daily weight loss. It is important when washing an egg that the water temperature slightly exceeds the temperature of the egg and that the egg is carefully dried with a paper towel. If a cool liquid comes in contact with the eggshell, the liquid will be drawn into the egg along with any pathogens on the surface of the egg.
If the problem is not corrected by washing the cuticle off the egg, then more drastic measures are required to increase transpiration. Sanding can be used to reduce the shell thickness and increase fluid evaporation. Begin by lightly sanding the egg with very fine sandpaper. I prefer to sand the small end of the egg first and continue to the large end if more sanding is required. Sanding over the air cell will increase weight loss faster than it will over any other part of the egg. There are eggs that require repeated sanding to achieve the desired daily weight loss.
It is important to practice with chicken eggs or other infertile eggs before attempting to sand a fertile parrot egg. It can take time to develop the finesse required to sand eggs without breaking them or jarring the eggs in the process.
I begin weight management on all eggs as soon as the eggs are removed from the nest therefore I have never been forced to put a pinhole in the shell to expedite weight loss. Doing this can introduce pathogens into the egg and should not be done, except in desperate cases when the egg must lose a great deal of weight and hatch time is near. Yet, in many cases where this method was utilized, the procedure was unsuccessful in producing a Hyacinth chick healthy enough to survive for very long.
The egg is moved to the hatcher once drawdown has occurred. Although, the incubator must normally be kept very dry, the humidity in the hatcher should be high to prevent the inner shell membrane from adhering to the chick. If the membrane dries over the chick's beak and nares the chick will suffocate. The chick's movement can be restricted by dried membrane making rotation impossible and the chick will not be able to hatch without assistance. In my hatcher the wet bulb temperature is near 93°F (33.9°C), which corresponds to a relative humidity of about 83 per cent.
About 27 days after the egg is laid the chick will be ready to hatch. This period may vary by a day if the correct incubation temperature of 99.5°F (37.5°C) and hatcher temperature of 98.5°F (36.9°C) have been maintained and weight management practiced. Pip occurs at 48 to 24 hours prior to hatch. I normally hear vocalization from inside the egg 25 hours before hatch.
Hatching is the most dangerous part of any chick's life; mortality is at its peak during hatch. Most Hyacinth eggshells are thick (even after sanding) and many chicks will need assistance. Assisting a hatch is exceedingly stressful. Yet, there are things that can be done to reduce the stress. Preparation and practice are the keys to successfully assist a hatching chick.
You should prepare all that is needed to assist. A hatch kit made up in advance will make this difficult situation a little less traumatic. You will need cotton swabs, sterile gauze pads, paper towels, tweezers, large needle and tincture of iodine, blood clotting or cauterizing agent, sterile water, plastic wrap and medical tape. Prepare a work station near the hatcher that is clean, free of clutter, comfortable and has good illumination.
I always recommend practicing any difficult procedures on infertile eggs. When working with infertile chicken or parrot eggs it is possible to develop a sense for how much pressure it will take to penetrate the shell, to know how much of the shell will break off when trying to remove tiny pieces and to master the skill required to avoid tearing the inner shell membrane. However, in an egg that is still filled with albumen the inner shell membrane is more fragile and will tear easier than one that is almost ready to hatch. So, do not become too discouraged if you tear the inner shell membrane while practicing.
When to Assist
If I hear vocalization from inside the egg and the chick has not piped the shell, I place a small hole, about 3 mm in diameter, in the air cell at the large end of the egg. For me this is easiest to accomplish with a large needle. I do not poke a hole into the eggshell, instead I gently scratch at the surface of the egg until I can lift away a tiny piece of the shell. By scratching at the eggshell, I am less likely to poke the chick with the needle. With most species it is not considered prudent to open the egg in order to permit more oxygen into the air cell. The build up of carbon dioxide in the air cell causes the hatching muscle (on the back of the chick's neck) to twitch, which in turn causes the chick's head to jerk and brings the egg tooth into repeated contact with the eggshell, eventually cracking the eggshell. Hyacinth chicks may not be able to crack the shell and they will die of suffocation. It is not uncommon for a chick to rotate 360° inside the shell and never penetrate the shell sufficiently to hatch. These observations are not restricted to the eggs I have hatched. They reflect the experiences shared with me by many Hyacinth breeders worldwide.
The chick is in need of assistance if you hear frantic screaming or if the cheeping becomes weak and begins to fade. I have learned that it is safer for me to begin assisting a hatch a little too early rather than to wait too long. I once became anxious and opened an egg to assist a hatch 56 hours too early and I still managed to hatch a healthy chick. On another occasion a chick pipped internally and appeared to be progressing normally. However, I checked two hours later and chick had died. Checking a hatching chick once every two hours, 12 hours after either external pip or vocalization is first heard, is usually sufficient.
If oxygen can be administered quickly it is sometimes possible to revive chicks that are limp, blue and appear to be dead. During an assisted hatch Ken Warthen DVM, found that the Hyacinth chick showed no signs of life when he opened the egg. He rushed his chick to a nearby veterinary school, where he administered oxygen and saved the chick. Approximately 15 minutes elapsed from the time that Dr. Warthen discovered the limp chick till oxygen was administered.
Although a hatching chick will not require a sterile environment, clean conditions are essential. Wash your hands or use new gloves each time you handle the egg. When you begin to assist a hatch, place the egg on a clean, paper towel. Folding this will create some cushioning and will help keep the egg from moving too much while you work. It is important not to keep the chick out of the hatcher for too long or it will become chilled. After each session discard or clean all materials that have become soiled.
Keep a small container of sterile water in the hatcher so that the water is at a comfortable temperature for the hatching chick. After removing any eggshell, wet the inner shell membrane with the warm sterile water using either a cotton swab or a paintbrush. Paintbrushes are easier to manipulate than cotton swabs and they do not leave fibers on the membrane. However, they must be used only for hatch assistance and they must be cleaned and boiled often.
Active blood vessels will appear either red or pink when water is applied to the inner shell membrane. If they are inactive they will be brown or they will have receded completely and will no longer be visible. If there are no active blood vessels it is safe to cautiously continue with the hatch assistance.
I practice a technique that is a little different than most aviculturists use, which permits me to see if blood vessels are still active with less handling of the egg. Before returning the hatching chick to the hatcher, I wet the membrane and partially cover the hole in the shell with a small piece of plastic kitchen wrap. The plastic wrap is secured with thin strips of medical tape. I am careful not to cover the chick's nares or mouth so that the chick is able to breath. The plastic wrap contacts the inner shell membrane thereby diminishing moisture loss and allowing active blood vessels to remain visible for a much longer time. Since there is a clearer view of the blood vessels it is easier to determine when it is safe to resume assistance. The inner shell membrane is also less likely to dry and adhere to the chick.
When a large portion of shell has been removed and the chick appears ready to hatch it is vital to examine the interior of the egg to be certain there are no active blood vessels at the small end of the egg or under the chick. If the blood vessels have not completely receded the chick and what is left of the eggshell should be placed in a small container so that the chick cannot force its way out of the shell, which could result in the chick bleeding to death. The navel should also be examined to make sure that the yolk sac has been absorbed into the chick's body. An unabsorbed yolk sac can cause many complications especially if it is larger than the size of a pea. An experienced veterinarian should be notified since surgery may be necessary.
Post Hatch Procedures
After a successful hatch inspect the chick carefully. Check its toes, beak and neck. If the chick was slightly malpositioned you may see some abnormalities in these areas. If the hatch was wet, there is a greater chance that the chick has a deviated maxilla.
The sooner these abnormalities are recognized the sooner and the easier it is to correct them. Record all information about the hatch and any difficulties that were encountered. Note what the inside of the egg looks like: Is it clean? Is there fecal matter inside the egg? Is there an unpleasant odor? This information may be helpful if the chick develops any problems. It may also prove valuable when hatching future chicks. Be certain to observe and record the color and texture of the skin, especially in the area around the navel.
Babies should be cleaned with warm sterile water and gauze pads. Then the navel must be treated. I prefer to use tincture of iodine rather than Betadine solution. Great care should be used when applying tincture of iodine to the navel. If it comes in contact with the chick's delicate skin, it will burn the skin. However, it is much better at preventing navel infection then Betadine solution. A sanitized eyelash separator can be used to fluff up the chicks down.
Before moving the chick to a brooder that has been warmed to 97°F (36.1°C), the chick should be placed in a small container, with straight sides and returned to the hatcher for four hours. Line the container with a several layers of paper towels and pieces of crumpled tissue paper to provide it with a soft comfortable place to sleep.
Tuesday 14th June 2022
It has been brought to my notice that the article by me about the Glaucous Macaw published in the Parrot Society UK magazine in 1992 was missing from the website page where it should have appeared. I have corrected this now and the article can be ... Read More »
" Naturam expellas furca, tamen usque recurret "
( If you drive out nature with a pitchfork, she will soon find a way back)
Horace (65-8 BC)