Micromonsters - Health and Husbandry in Aviculture - Aspergillus Sp.

Disclaimer - I am in no way a vet and do not claim to be, it is probably likely that you are also not a vet. As birdkeepers we can however arm ourselves with the information we require to manage our birds effectively and reduce the chances of poor health. This DOES NOT mean that this information or the practise of preventative husbandry is a substitute for GENUINE VET CARE AND TREATMENT. If you have a bird that is sick and you are looking here for help, you are far too late for this to be useful, please contact your vet immediately.

I TAKE NO RESPONSIBILITY FOR THE USE OR MISUSE OF INFORMATION AND LACK OF VET CARE, THAT REMAINS YOUR RESPONSIBILITY AS THE KEEPER OF YOUR BIRDS.

Before we start, two things, I am not going to go through the veterinary side of things here as that is not the focus of this series of articles, also I will not be filling the article with tons of gross pictures of infections, I trust if you would like to learn more on that front you can do so but it would not be needed here.

Let's crack on...

In this action packed instalment of Micromonsters we are going to look at a group of pathogens very commonly encountered in aviculture and the wider world, this group are the Aspergillus Species.

For the uninitiated I am going to quickly go through the terms you may have heard before but become confused by so that everyone is clear moving forward. The term Aspergillus refers to the organism itself as the causing agent, in the sense that matches cause fires but they are not fires themselves. Aspergillosis is the disease caused by the organism itself if favourable conditions prevail, the "fire" if you like. One other term often used is Aspergilloma, which refers to a very localised and sometimes long term colony of Aspergillus present within the bird itself.

If you read the introduction to this series you will know that Aspergillus species are fungi, specifically affiliated with the moulds. There are a about 250 species within the genus Aspergillus which is why I generally refer to them as Aspergillus Sp. here as there are several of note that will have the same effect on our birds, but they can in practise be treated more or less the same.

Any bird (and many other animals) can be effected by Aspergillosis but some are more vulnerable than others, often because of prevalent conditions and the needs of that species.

Some Birds species often vulnerable include -

Penguins - Coming from and requiring water these birds are more likely to be exposed to high humidity, their flightless nature places them much closer to the source of infection, at nesting time in particular. In the wild the saline nature and movement of the water nearby would reduce incidence of fungal pathogens, often in human care however, penguins are kept in freshwater which does not have the same effect.

Snowy Owls - Coming from very cold climates where pathogen pools would be strictly limited by the temperature, these birds (and some other cold climate species) can become vulnerable when kept in temperate climates where spore count is high and resistance low.

Birds of prey - Species which have evolved for a high level of performance in turn have advanced respiratory systems which can easily be compromised by the wrong conditions.

Pionus Sp. - Medium sized members of the parrot family often hailing from the humid could forests of the Americas, these species display a strong resistance to Aspergillus which becomes their undoing in the company of humans, as they will hide symptoms so well for so long that it is often to late to treat by the time to problem is identified.

Tropical Birds of various species - Quetzals, Trogons, Turacos, Toucans etc.. can be more vulnerable due to the higher humidity they require to thrive.

This is just a small selection of the more common candidates, but again under the right circumstances any birds can succumb.

Members of the Genus Pionus are known for being at high risk when it comes to Aspergillus. This Handsome spectacle is a White Crowned Pionus if you were wondering.

The initial damage to our birds is centred around the lungs, with the organism being inhaled, groomed from feathers or already present and taking advantage of individuals in an immunocompromised state, without a healthy immune system to defend the body the pathogen can run rampant, growing through the lungs and producing breathing difficulties for the bird. If left untreated in later stages the toxins produced by the fungus itself will find their way into the bloodstream causing the kidneys to struggle and eventually death will occur, often birds do not even make it to this stage in advanced cases.

It is important to stress the fact that under normal circumstances a healthy bird can easily deal with a normal amount of Aspergillus spores and indeed they are present in almost every environment (not to creep you out, but I could say with reasonable certainty that there are some on YOU right now. It is generally only when a bird is struggling with something else that it will succumb to an infection of this type or in certain cases where conditions are poor the bird can be absolutely overwhelmed by spores to the point that it's immune system becomes exhausted, but this is rare in good conditions.

When we want to try to prevent this in our birds we must look at two things, avoiding the situations that compromise our birds and make them vulnerable AND reducing the pool of pathogens around them. Of course eliminating them completely would be next to impossible but reducing them significantly will reduce the chances of mass exposure and it is here where we can use careful husbandry planning to help ourselves and our birds.

So looking at reducing compromising situations we are looking generally at stress and health. Stress as mentioned in other articles is subjective to the bird, that is to say that you do not know what that bird experiences or perceives as stressful, therefore we must consider the behavioural cues we receive from our birds that may tell us a few things. Instances where birds try to move away or escape are clear indicators that the situation is causing fear or pain, both of which will cause stress to the bird. Stress can also be social, is the bird in an overcrowded aviary with others it does not feel comfortable with. Falling into the age old "in the wild" trap is easy here as yes, often many species would co-exist together in the wild, but NEVER under enclosed circumstances such as we find in aviaries, the option to leave an area and cool down would always be available in the wild, alas in aviaries, it is not. Such problems ignored can easily escalate into a feedback loop of stress which finds no relief and you guessed it, over time the end product is an immunocompromised bird that is a prime target for an opportunistic fungus or worse. Remember to monitor behaviour and take note from other keepers that have mixed bird species before, they usually speak from a point of having already tried and failed with some species. Obvious examples are predatory species with prey species and species that are known for being territorial. They will often be fine for a while, with social stress only becoming obvious at a later date when it is to late to undo the stress caused.

Training our birds can have a massive effect in this respect as potentially stressful situations can be converted into good ones to some degree, a fine example is crate training, this involves teaching a bird to enter it's crate or box voluntarily which then massively reduces stress by avoiding a catch up with traditional net techniques or rounding the bird up manually and restraining by force, which are all traumatic experiences for most birds. Catching and transport can be a major source of stress and often individuals can be struck down shortly after arrival at their new quarters once the fallout of the journey kicks in. Allowing our birds to be active participants in their care increases their feeling of control and therefore reduces stress.

Frustratingly the stunning Resplendent Quetzal and it's relatives are known for high mortality rates in human care connected to Aspergillosis.

General husbandry can have an impact by keeping things clean and making good choices in design and maintenance. A well designed aviary with plenty of space for exercise will allow your birds to remain in optimum health. Appropriate shelter for that species needs to be offered depending on the conditions you keep them in. Good hygiene is critical to good health and I would hope that I can gloss past this on the assumption that if you have got this far you already know this. Selecting a good disinfectant which covers fungal species as well as the other pathogen groups covered in the introduction will help here.

The main point of concern when looking at Aspergillus is choice of substrate and air conditions within the flight and or shelter. Aspergillus thrives on carbon based substrates and breaks down the various sugars found in them as food much as other moulds would. The main offenders are dusty substrates such as bark, shavings or sawdust which when combined with humid conditions and poor ventilation provide an incubator for Aspergillus, sending the spore count through the roof and presenting a ticking fungal time bomb for our feathered inhabitants. When selecting a good substrate to reduce these issues, often substrates such as dry clean sand can be effective as they offer little in the way of home comfort for Aspergillus, sand also has desiccant properties if kept dry and will further dry out any feces that might offer pathogens an outpost. The flip side to sand is that it is heavy and requires regular changing if you wish to keep it clean with large birds, it is however worth it if you can make it work. Other organic substrates with low spore counts are available which present a considerable improvement on bark and other waste wood based options, these include Hemp, Miscanthus and Aspen to name just a few. Do some research into what works best for you and the environment within your aviaries. Another thing to consider is the vegetation in the aviary, fungal spores can thrive on decaying leaves and vegetable matter so keep plants trim and healthy and the floor tidy.

Meet the delightful Aspergillus fumigatus, one of the main offenders from it's genus. Seen here sporting Prussian Blue.

Finally we must address the air within the aviary. Outside is not so much of an issue but usually poorly managed shelters can be a problem. A good level of air flow is needed, usually you can tell if somewhere feels fresh or stale just by sensing the air, does your shelter feel stuffy? does it smell fresh or damp? These obvious things are indicators you would use in your own home and often have the same causes. If you are in doubt, get hold of a hygrometer (usually available at reptile stores or online) and see what sort of humidity levels are common, anything higher that about 60% will lend itself to aiding fungal growth. One concern is that some species of bird require high humidity to be comfortable, and so you can see how ventilation is important as it is the only other means to easily reduce mould growth in enclosed conditions.

In conclusion we cannot protect our birds from exposure to Aspergillus and resulting Aspergillosis therefore we must focus on the influencing factors and reduction of the pathogen pool as a preventative before the disease occurs.

To recap -

Reduce stressful situations, monitor behaviour, consider where training could help you here.
Maintain general good health and an environment which allows exercise.
Keep everything clean and dust free, remove old food.
Keep things as dry as your birds needs will allow.
Maintain good ventilation in all areas
Choose an appropriate substrate for your conditions.

If you are lucky some of these precautions should also reduce some other pathogens as well as Aspergillus, reducing chances further. Air filters are available if you want to go the extra mile and reduce dust in the air and in certain environments these can be a blessing if managed correctly.

I hope this has been an interesting (and thankfully brief) introduction to the fungal horror which hides in plain sight. Forewarned is forearmed, have a think about areas within your aviaries that could be a risk, can you make any changes to improve them?

Until next time, keep giving your birds the 110% they deserve!

C.