Health & Nutrition
Eclectus Parrot Digestive Tract1. Introduction
2. Gut length
3. A better explanation - they're not granivores
a. Dr. Rob Marshall's reports
Eclectus parrots are a unique species in a lot of ways. The color differences between the sexes are so great that at first it was thought that males and females were members of different species. Unlike many bird species where the young all look like females and the males get their distinctive coloring at maturity, the color differences in ekkies are obvious from the moment the babies get their first pinfeathers. Most parrot species are monogamous and bond for life, but ekkies have a double polygamy system where every bird has several opposite-sex mates at the same time (Scienceblogs).
They're different when it comes to feeding them too. No one really knows why, but it's generally agreed that eclectus parrots are more sensitive to diet than most other parrots. When something in their food doesn't agree with them, they're prone to problems like involuntary toe tapping and wing flipping, as well as unwanted behaviors like screaming, aggression, and feather destruction.
It's sometimes said that the reason they're more sensitive to
diet is because they have a longer digestive tract than other parrots. But
it's very questionable whether this is actually true, and there's another
explanation that makes more sense.
The general idea behind the gut length hypothesis is that the wild diet of ekkies is relatively low in nutrients, so they have to be super efficient at absorbing the available nutrients and have evolved a longer gut to help them do this. When you feed them a more nutrient-dense diet, they experience a nutrient overload and this causes problems. See ParrotParrot for an example of this thinking. The part about the wild diet being relatively low in nutrients is apparently correct, but the rest of this idea is shaky.
There doesn't seem to be any actual research on the gut length of ekkies, just some anecdotal reports of vets who did a necropsy and said the gut length was longer than other parrots, and other anecdotal reports of vets who did a necropsy and said the gut length was not longer than other parrots. So no agreement there.
In any case, gut length is changeable and depends on what the individual has been eating. Klasing page 112-113 says that "The length of the intestines increase with increased food intake or increased dietary fiber. For example, a 34% increase in dry-matter intake by Japanese Quail induces a 43% increase in the length of the small intestine." The book also indicates that the size of the ceca changes (in birds that have them), and the size and strength of organs like the gizzard will also change. It takes a few weeks for these major differences to develop, but there are more subtle changes that can occur over a few days or even in the course of a single meal.
To get a meaningful comparison, you would have to compare ekkie gut length to a bird from another species who has been eating the same diet. Ekkie owners are strongly encouraged to feed their birds a lot of fiber, so when longer intestines are observed it might simply be a reflection of their diet, and not something that's an intrinsic feature of their anatomy.
Changes in an individual's intestine length due to diet changes are called gut length plasticity, and they have been reported in fish, reptiles, and mammals, as well as several species of birds from a variety of families (Zandonia et al, Naya et al). Presumably it happens with amphibians too; I haven't looked for info on them. When a characteristic is observed in every major branch of the vertebrate family tree, from the oldest to the newest, it's fairly safe to assume that it evolved very early and is very widespread, and it would be an exceptional species that did NOT have this trait. So until we receive information to the contrary, it's conservative to assume that diet influences the gut length of individual ekkies just as it does with so many other species.
The most authoritative source of information on the dietary needs of eclectus parrots that I've seen is Dr. Rob Marshall, a highly respected avian veterinarian in Australia who has a special interest in ekkies. He has a 38-part series of short Youtube clips on the subject that begins here. Clip 17 talks about ekkie digestive anatomy, but it does NOT mention intestine length, so it doesn't look like he considers it to be a relevant subject. Here's what the notes accompanying the clip do say:
"These are the key features of Eclectus digestion. A large crop, wide thoracic esophagus and highly elastic proventriculus of Eclectus are morphological adaptations aimed at increasing food-holding capacity needed to accommodate a wet bulky wild diet. More time is needed to physically and chemically digest this increased volume of food in the proventriculus. Less time is required in the gizzard because fruit pulp lacks coarse fiber and seeds have already been broken into small pieces by Eclectus before they are swallowed. After the food is processed into small particle size by the milling action of gizzard muscles it moves into and rapidly fills the small intestine providing an expansive surface area for final absorption to take place. A precise hormonally regulated crop emptying process maximizes the speed of meal digestion by releasing the second part of the meal - retained in the crop - into the proventriculus as digesta moves into the duodenum from the gizzard."
The video clip itself notes that there is "rapid movement through small intestine after leaving gizzard" with no mention of any unusual length.
An article from In Your Flock magazine includes extensive comments from Dr. Marshall. Once again he points out the key features of the ekkie digestive tract but never says a word about gut length or indicates that ekkie anatomy is significantly different from any other parrot. The article was actually written by an unidentified author who says that ekkies have a "different" gastro-intestinal system, but the source of this information is not identified. In general, the only comments in this article that I would take seriously are the ones by Dr. Marshall.
So what's really happening here - would an ekkie have the same digestive tract length as a similar-sized species that's eating the same food as the ekkie, or do they always have a longer digestive tract regardless of what they're eating? I don't think that it actually matters, because there's another explanation that makes more sense than the intestine-length hypothesis.
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Most parrots are classified as granivores, which means that seeds make up the bulk of their diet. It doesn't mean that seeds are the only thing that they eat, and many parrots eat other foods too such as fruit or insects. But seeds are the most important part of their diet.
Eclectus parrots aren't granivores. They are classified as frugivores, which means that fruit is the bulk of their diet. Once again, this doesn't mean that fruit is the only thing they eat, and it is NOT recommended that you should feed a pet ekkie primarily on fruit. But it does mean that you shouldn't feed them the same way you would feed a granivore, because they are adapted to a different type of diet.
The way that you SHOULD feed a pet ekkie is beyond the scope of this article, which is mainly concerned with why they are different from other parrots and not what you should do about it. It's best to seek out an ekkie expert for detailed diet advice. The pet bird community considers Laurella Desborough to be a leading expert in this area, and her Eclectus Centre is generally recommended as a good source of information. Dr. Rob Marshall's magazine article comments say that a granivore-type diet causes diet-induced digestive problems in ekkies. He recommends feeding cooked squash, sweet potatoes, rice, and legumes as the foundation of the diet, with some fruit and other vegetables to provide more vitamins and minerals.
So how are frugivores different from granivores? Sweet fruit is considered to be a poor source of nutrients compared to nutrient-dense foods like seeds, nuts, grains, and fatty fruits (like palm fruit). Sure it's got some vitamins and minerals in it, but parrots aren't known to seek out that stuff. They mainly seek out calories and protein. A gram of sugar has less than half the calories of a gram of fat, and the protein in sweet fruit is almost nonexistent, so it's a second-rate food source compared to seeds. See the Fruit article for more information.
But there's a lot of competition for the richer food sources, so many species have adopted a strategy that lets them thrive on the less-rich foods. But this means that they have to be super efficient at extracting the available nutrients from these nutrient-dilute foods. Give them a lot of nutrient-dense food (like a granivore's diet) and there's likely to be trouble.
So how frugivorous are ekkies? There isn't any formal documentation that I can find, but it seems to be generally agreed that they're frugivores and not something else. Sugarloaf Animal Hospital says "They are not obligate frugivores, but as much as 80% of their wild diet is reported to be fruit in some ecological studies." I couldn't find the studies, but Forshaw mentions three sources that found lots of fruit-eating.
Dr. Rob Marshall's reports. Dr. Marshall's Youtube series goes into detail about the observed diet of a wild ekkie family of three males and a female. The format is inconvenient - there are 38 short clips that have to be navigated while trying to read the notes below the video before the clip ends. So I'll report the most significant parts here.
The notes for Clip 2 say
"Eclectus are classified as generalist frugivores. This means they eat mostly fruit pulp in the wild. We collected and identified rainforests foods known to be eaten by Eclectus. We also discovered new foods. Our findings reconfirmed the frugivory status of Eclectus."
The notes for Clip 3 say
"Our study divided known Eclectus foods into 4 categories. The first and most important category consisted of fleshy pulp and soft skinned fruits. Most fleshy fruits collected were sugary. Others were clearly lipid. The fruit pulp wild diet of Eclectus parrots is considered nutritionally compromised because of its low protein content. Apart from fruit pulp Eclectus parrots also feed on seeds, aril, leaf buds, blossoms and nectar to satisfy additional nutritional needs."
The text on the actual video clip says that fleshy fruit pulp was more than 75% of the diet. As mentioned, most of it was sugary, but the diet did include some palm fruit which is fatty not sugary. Presumably the birds were mostly eating ripe fruit, since unripe fruit is not sugary.
Clip 4 says
"The seeds eaten by Eclectus are small. It was expected that the seeds within hard cased fruits would compensate for the low protein levels of fruit pulp. Nutritional analysis of hop bush seeds and red ash seeds was undertaken. Crude protein levels were surprisingly low in these seeds."
Clip 5 comments on eating fruits with an aril but doesn't say anything particularly informative. An aril is a bit of fruit attached to a seed that is encased within a larger, inedible covering. Pomegranate is an example of a fruit with arils. The fruits shown in the clip are northern tamarind, red beech, and fire vine.
The notes for Clip 6 say
"Although not a major part of their diet, leaf buds, blossoms and nectar represent an additional energy and micronutrient resource during times of limited food supply. Our findings support previous claims that fruit pulp constitutes the major part of the wild diet of Eclectus parrots and that the wild diet is limited in protein. The digestion dilemma of frugivory is to find ways to overcome the challenges presented by this type of nutritionally dilute, protein limited diet. Frugivorous birds solve this problem by eating and digesting large volumes of fruit pulp. This food must move through the gut quickly but also be retained in the stomach for the time needed to fully extract protein from it. Eclectus meet this digestion challenge by morphological specialisations of their digestive tract incorporated with highly regulated foraging behaviours and peculiar eating habits."
The actual video clip says "Wild Diet: bulky, watery, sugary fruit pulp; seeds much smaller part of diet; protein limited". Certain species of leaf buds can be very high in protein, and this doesn't seem to be particularly well known. So the birds' protein intake might not be quite as limited as thought, even though the leaf buds are just a small part of the diet. The Protein article has some additional info on bud protein.
The hens would need a lot of protein during the breeding season to support egg laying and chick rearing. Does the diet change at this time? Do they eat some bugs to provide protein? We don't know. Bug-eating might be harder to observe than a bird that's gnawing on a piece of fruit. Eating insects to supply certain nutrients is a common strategy for nectarivorous birds, which also have a high-sugar diet.
Dr. Marshall's magazine article comments say that the birds that were studied in the Youtube series went foraging twice a day rather than eating all day long. Marshall says that their feeding habits facilitate a fast transit time through the gut. He says that feeding them in a way that reduces the rate of passage causes problems.
So it seems that the diet-related problems that are common in ekkies may be related more to the speed at which they process food than to their gut length. A granivore-style diet may move through the system too slowly for them. Slower passage allows more time for absorption of nutrients, but this is not what eclectus parrots are designed for.
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