In the lovebird community, we are all aware of breeders who want to develop larger birds over time for exhibition purposes.  Breeders select within lines, varieties or mutations and continually seek small increments in size with each generation.  In order to quantify the increase in size and move ever forward, the meticulous breeder will assess the average increase in individual and family size, and base pairings on the results.  The most startling evidence of increased size in the roseicollis is, or was achieved through the development of the Longfeather, or its progenitors.

Given that increase in size is possible, and that movement in one direction is usually balanced by movement in an opposite direction, there is nothing to prevent the appearance of a contrastingly diminutive bird. Some will ask: Why on earth would you want a small bird ?  Small birds can't compete in exhibition and you are altering the bird without reason.  True enough, but what happens if you do develop a bird that is smaller than the average?  How much smaller would it need to be in order to be considered a smaller type ?  Can size reduction be accomplished through chance production of smaller or dwarf birds, and under what conditions might a smaller bird be considered acceptable as a type ?

The Longfeather is said to be larger than the standard roseicollis (standard because we are discussing exhibition birds, not the nominate), but that difference is not simply an increase in height, but also feathering, color distribution and hue as well as skeletal size (leg diameter, head size, etc...).  As you will see later, the recorded size of lovebirds is almost as flexible as the use of weights to differentiate between birds.

I was recently informed that the offspring of a Longfeather "X" Longfeather mating can produce a variety or assortment of chick sizes and form in the nest, some of them being very small and bright indeed.  If this is the case, would these smaller birds represent a new variety if bred together for that purpose ?  Would they produce a certain percentage of normal or Longfeather roseicollis, or would they simply revert towards an ancestral type (atavism) ?  Would they be dwarfs, hybrids or wasters ?  I know that I have seen and heard of runts in roseicollis, but not "dwarves" except where people might mistake a hybrid.  The question that arises between runts and dwarves seems to be one of precision and measurement.  Does a one centimeter difference in height justify classification of a smaller bird as a dwarf ? No.  Is two centimeters enough or is a greater disparity required ?

Many have read the internet article about Congenital Chondrodysplastic Dwarfism in the Fischer Lovebird.  The article suggests that few cases of dwarfism are reported for caged birds.

A brief description of congenital dwarfism from that article follows:

• "We describe a case of congenital malformation in a Fischer’s Lovebird that had gross and chondrodystrophic histologic lesions similar to those described in congenital dwarfs of other animal species. The gross and histologic changes in cartilage and bone of the necropsied lovebird were consistent with disturbed endochondral ossification, and included short limb length, disorganized columns in the growth plate with cartilage fibrillation, and widening of the metaphysis. A genetic basis for chondrodysplasia is suggested by the consanguinity of the parents and the presence of another bird with proportionate dwarf characteristics hatched in a subsequent clutch. "

What Might Constitute or Cause Dwarf-like Alterations in our birds

Breeders routinely look into the nest chamber when eggs are due to hatch to make sure brooding and hatching is progressing well.  Observant breeders are accustomed to seeing healthy active nestlings: dry or drying down and the chick laying on its back or side for several days (potentially more, depending on the mutation).  If more than one chick is present the bodies are usually so entwined, to maintain warmth, that it is difficult to determine exactly how many youngsters are in the nest.  Bodies, heads and legs are akimbo, and the chicks look like a ball of writhing earthworms or perhaps more accurately, like a Gordian knot, where it is sometimes difficult to determine which organ or limb belongs to which chick ( slight exaggeration, but fun to visualize !) and where one should begin to separate them.

The interested breeder will usually, but not infallibly, recognize small differences in chicks, if differences do indeed exist.  Examples may include chicks hatching in very moist conditions, where the chick appears swollen and is moving lethargically: quite the frightening experience for the novice and expert alike.  This physical condition can give a breeder reason to think something is wrong with the parental pairing, but it usually has more to do with moisture in the air and absorption of that moisture by the chick during the days preceding hatching.

Conversely, in dry conditions, hatchling chicks may still move very slowly, but appear weak and excessively wrinkled; lack the tone and "plumpness" of the newly hatched, or in a worse case scenario fail to hatch.  These "dry or dehydrated" birds are often slow to eat, their crops are small, and without immediate assistance from the breeder, through electrolyte feeding, will likely die ( I feel that immediate transfer to a controlled "moist / humid" environment might assist with re-hydration of tissue and so assist the bird in crop expansion and recovery, but have not been able to do this.  Has anyone studying dehydration performed tissue re-hydration studies and feeding - this implies immediate or almost immediate hand-feeding: please do not undertake this without the requisite knowledge.  Hand feeding experience, a brooder and climate controlled environment and knoweldge of early additives are essential).

Even with the best intentioned intervention by practical breeders, survival rates can be depressing.  While these conditions may cause a novice to jump to conclusions regarding parental consanguinity, it too, is almost always an environmental matter: one where not enough calcium was provided to the hen to enable sufficient shell to be laid down over the ovum; there was excessive or uncontrolled breeding activity and extreme conditions in and around the breeding room (too humid or too dry), and all of these factors contribute to the devestating end result.

Chicks are sometimes considered runts if: produced in later rounds (3^rd nest or more); are the last hatchling in a big clutch; food is sparse or has little nutritive value; hens are in poor breeding condition and growth conditions for the egg and embryo are abysmal.  Inbreeding over many generations without careful selection, can also result in size reduction and sometimes sterility, where a breeder has failed to focus enough attention on maintaining these essentials.

Is consanguinity a cause of dwarfism ?  No, it is not the cause, although it may be responsible for cluster, versus scattered presentation of commonly "hidden"  congenital aberrations.  Close family linkage between birds will invariably result in a greater percentage of recessive "defects", over a relatively short time period, and then, if managed properly, will also disappear rapidly.  Why ?  The close mating of family individuals creates the opportunity for "hidden" genes to combine more frequently, where they are carried by individuals, because the gene pool is limited in a controlled selection process.

Deleterious genes are present in a heterozygous or "non-inbred" population, but tend to make there appearance in a significantly lower percentage of the time, due to the vast number of potential gene combinations.  In a heterozygous population or a stud that includes a lot of out crossing, the deleterious genes are always in play, but it is a matter of chance or odds as to whether they will express themselves in the offspring.  Inbreeding quickly hi-lights recessive faults and while it may seem that inbreeding is the cause of congenital aberrations, all inbreeding does is provide a mechanism for revealing the hidden gene (s), and enable the skilled breeder to extricate those genes from a specific line of inbred birds.  Similarly, there are birds or families of birds that may or may not be more susceptible to specific inherited abnormalities than others, consequently the practical requirement for a number of select families when beginning inbreeding practices.

What does all of this mean ? Inbreeding can result in more aberrations over a relatively short time (and that would undoubtedly rely on the statistical method and parameters established to assess hidden gene potential), but it should not be equated with "creating" inheritance problems.  The probability of deleterious gene combinations exist in the population as a whole, not a single family.  "Normal" or nominate birds may produce chicks with congenital aberrations, but these chicks will rarely survive to the juvenile or adult state, where the health of the bird is paramount to survival.

Some individuals equate the presence of supremely healthy birds in the wild, with a lack of deleterious genes.  The fact is, that wild birds are supremely adapted to their environment, and mutations or hybrids, that are not adapted, rapidly disappear.  Consequently, the "mutations" are not changes or alterations which will benefit the population as a whole.  Further to the success of a bird in the wild, may be a prolonged growth phase, versus a rapid one.  Rapid growth requires access to a lot of food on a regular basis, while slow growth may be a natural development to address the fluctuations in food cycles.  If we look at the size and intake of exhibition birds today, how many of you would think that a hen in the wild would be able to provide the feed demanded by fast growing, demanding exhibition chicks without considerable chick mortality?  How many trips are normally averaged by the cock during the feeding of slower growing wild stock ?  A similar example may be taken with chicks in the wild that are left for longer periods of time in the nest, by themselves.  The exposure to colder temperatures for extended periods, would assist wild chicks to better handle temperature fluctuations than chicks raised in a climate controlled home or temperature controlled aviary.

It is well known that recessive sex-linked dwarfism in poultry can result in significant reductions in bone length, structure and weight.  In some instances poultry crosses may result in full sibs with weight differences ranging into the 40 % mark.  This is a huge shift or differential in size.  Strangely enough, the dwarf state is generated in the heterozygous gene combination rather than the homozygous one.  The trait, while sex linked, is not evident at hatching or for several months after.  Following this period, birds proceed to normal sexual activity at maturity.  In another scenario, a recessive condition can result in an obligate lethal character.  Birds can display severe expressions of dwarfism: beak aberrations, claws bent ventrally, usually followed by death within two weeks,  some live longer,  consequently, the potential for an obligate lethal [semi-lethal or delayed lethal] characterization

Dwarfism as a Mathematical Expression

The article on the dwarf Agapornis fischeri suggests that dwarfism might be defined by a percentage range reduction in size from the "normal" or mean population size.  It suggest that any bird that is 20 to 30% smaller than the norm, could be a dwarf.  In the case of Agapornis roseicollis, we are looking at an exhibition bird that is approximately 17 centimeters or ~ 7 inches from the top of the head to the tip of the tail.  A 20 to 30% reduction in size would indicate that an exhibition roseicollis would need to measure between 11.9 and 13.6 cm in order to be awarded dwarf status.  However, If we target a bird at 15 cm as the norm, as might be the case in the nominate bird ( 6"),  dwarf status would require roseicollis to be approximately: 10.5 to 12 cm.  in height.   In any event, what is clear is that one is looking at a very, very small roseicollis.

Not all dwarves will present obvious physical aberrations or asymmetrical form with a reduction in size.  One of the challenges associated with a height or size definition or determination for dwarfism occurs when chicks hatch that are of proportionate size and structure, and lack any overt physical evidence of dwarfism.  In this case it is far more difficult to identify dwarfism with any certainty, without a necropsy.

Realistically and pragmatically, it would seem more appropriate to assess roseicollis dwarfism based on the nominate bird's size, versus the size that has resulted from breeding exhibition stock.  An exhibition chick, which matures into a bird of only nominate size could obviously not be called a dwarf, as size specifications are invariably set by the nominate species.

What size is one really looking at, comparatively speaking, if one wants to visualize a roseicollis dwarf state ? If the calculations and projections are accurate, a roseicollis would need to be significantly smaller in stature than a Nyasa or Madagascar.  When researching suggested lovebird measurements it is necessary to attain / calibrate sizes from a similar source, so:

• a roseicollis measuring 17 cm is comparable (application of equivalent parameters and devices to "measure" different species) to a:14 cm. lilianae; 13 cm. cana; 16 cm. taranta, 15 cm. fischeri, 16 cm personatus, and 14 to 15 cm nigrigenis, etc...

• In another instance, roseicollis size varies between 16 & 18 cm, while lilianae range between 13 &14 cm; cana between 13 & 14 cm; taranta between 15 &16.5 cm;  fisheri at 15 cm,  personatus between 14 & 16 cm and nigrigenis between 14 & 15 cm

Dwarf Description

I am including a photographic comparison between juveniles from two different nests, that are only days apart in hatch date.  However, there was and remains a world of difference in their size; down cover; wing length; feet; beak and overall capabilities.  The smaller bird (perhaps a dwarf: from the definition applied above) was smaller than all of its nest mates (2 others), it hatched second and was from the first round.  Needless to say I was not surprised by the appearance of this bird in the nest and just assumed it was a runt.  As time passed, it became apparent that the bird was indeed growing more slowly than its counterparts, was less able to hold large volumes of food in the crop and appeared to have thinner diameter legs (this was / is unusual), although the feet were larger than its nest mates.  It was and remains well proportioned, is active and seems able to hold its own.  I retained the bird because of a poor wing to body ratio.  I was under the impression that the wings would not be able to support the eventual weight of the bird, despite its lighter frame.  As well, the wings appeared fragile and much shorter than wing lengths of its nest mates (as of 2 April 2004, the bird has still not flown, while nest mates and birds hatched much later are flying around with little difficulty). Was it environment ? Unlikely.  Was it a possibility of consanguinity bringing to the surface a hidden gene combination ? Potentially. Is it just a slow growing chick that will catch up later ? Not likely.

The size of the bird has been more difficult to judge as it has grown. It looks more compact and heavier than its related offspring and other nestlings.  This is an illusion, as the bird is more heavily feathered than its counterparts, which only makes it appear larger.  In actuality it is far lighter and has a much smaller head, bill and overall body structure.  I thought of a Longfeather connection somewhere in the parental background, but the bone structure would be expected to be heavier rather than lighter, and the color has not developed any faster than usual on the forehead and mask.  The overall structure of the bird is not at all as broad as that described in the Longfeather.  Pictures taken of the bird do not do it justice in terms of its petite frame and the substantive difference in size.

The bird in question is the one on the right hand side of the picture below. I have examined it for beak deformities, lesions, ossification of bones or joints, thickening of digits or swellings at the joints, as one might expect in a dwarf, but have found no tell-tale signs. It is a "reasonable" miniature, and tends to sit lower and heavier than its nest mates.  Furthermore, it is obvious in a colony situation that the bird is significantly / substantively smaller than any of the other birds, even the smallest (discard), which it is compared to in the accompanying picture.  If you have any comments (measurement clarification or comment on insignificance or significance of measurements) or have experienced similar runts or dwarfs in your nests, lets start tracking their occurrence.

Does anyone have photos of Longfeather by Longfeather matings that result in tiny birds.  It would be interesting to post the pictures of the offspring for others to see and comment on.