Bird wellbeing – Why Welfare Assessment isn’t Always Water off a Duck’s Back

Dr Paul Rose is a lecturer in animal behaviour in the Psychology Department at the University of Exeter and he is a research associate for WWT, where he runs the Animal Welfare & Ethics Committee. Paul is the co-chair of the BIAZA Research Committee and of the ICUN Flamingo Specialist Group. He also teaches on the MSc Applied Zoo Biology for University Centre Sparsholt. He has been involved in captive animal research for 20 years.

Progressive zoos are moving forward with how they implement welfare assessments, striving to provide environments that facilitate the attainment of positive wellbeing for the animals that they house. Whilst always challenging to understand what animals are thinking and feeling, for some species, attempting the most accurate inference of animal welfare is easier than for others. Higher mammals for example, chimpanzees (Pan troglodytes) or gorillas (Gorilla gorilla), have been extensively studied. We understand their social system, their life histories, their evolutionary relationships, and their behavioural ecology. We can identify their highly motivated behaviours and determine behavioural choices that promote positive welfare states. All of this information can be used to judge the quality and suitability of husbandry, housing and population management for species under human care.

There are, however, a myriad of other species housed in the captive wild animal facilities where assessing welfare is much more challenging. One of the most taxonomically diverse of animal groups housed in zoos are the birds. And assessing bird welfare is notoriously difficult. Whilst birds are endotherms, like mammals, they share many traits of their reptilian ancestors and have a complex physiology and anatomy all of their own. Many also move in the most un-mammalian ways (flight), utilising vertical and aerial spaces in a way that may other species cannot, they have complex reproductive behaviours, a wide range of mating systems and different strategies of nest building and raising their young. It is not surprising that many of the tools we have for assessing welfare in mammals are hard to translate for birds or simply do not help with determining welfare states.

Birds lack facial expression and therefore mood or emotion cannot be visible in the same way for mammals. However, it is possible to look at body language, posture and orientation to describe underlying feelings and psychological wellbeing. Birds will hide signs of illness and stress, a survival strategy to keep them out of the sights of potential predators. This means that bird carers need to have a keen eye for what is “normal” behaviour, demeanour, and physical condition for their birds, and be ready to intervene when anything out of the ordinary is detected.

Captivity can impose constraints on what birds can do and therefore understanding of behavioural needs and choice and control over an environment is important in the assessment of welfare. Regardless of the size or style of enclosure, for nearly all flighted birds, the captive environment will pose restrictions on flight. It is important to consider what the bird may need from flight (and do we actually even know this?) when looking at welfare states. For example, flamingos housed in a covered aviary can keep all of their flight feathers, but will they actually be able to fly in a meaningful way? Would their behavioural welfare be improved by being kept in an expansive, open enclosure but have to be flight restrained? The flamingo’s physical health and wellbeing may be improved in the covered aviary as it is less likely to be affected by pest species entering its environment, it is going to be more biosecure against threats such as Avian Influenza and it can be easier to provide husbandry for (e.g. known food intake) as there is a barrier between the flamingos and other birds who may compete for food. From a control and choice perspective, the flight restrained flamingo in the expansive open enclosure and the fully-winged flamingo in the aviary are still going to have the choice of movement and control over where they go removed from them. In fact, the flamingo’s welfare in the covered aviary may be further impacted upon by the likelihood of collisions with aviary structures and netting if birds do attempt to fly.

If we compare the flamingo to other species of wading bird then the wellbeing and behavioural diversity of such species that perch or spend a large proportion of their of time off the ground are (as definitely as we can be) definitely improved by covered aviary housing that allows for free flight and perching off ground. Ibis, spoonbills, egrets, and herons should not be flight restrained, for example, as they breed in rookeries in trees, perch on waterside vegetation and regularly fly between foraging sites. In short, an enclosure designed for one species may not always be suitable for another, even though both species may appear to be similar in their ecology, anatomy and way of living.

Many of the welfare measures I have alluded to so far are resource based (they are inputs that we provide to the animals and we are assessing the relevance of these inputs based on the bird’s behavioural responses to them). We also need to think about underlying emotional aspects of welfare (the outputs from the environment that the animal is currently in) and these emotional aspects are often termed “animal based measures”. These types of welfare measure are much harder to describe and define in a repeated and robust manner. More work is needed on identifying emotional outputs (personality traits or descriptions of body language) that could allow bird keepers to assess a bird’s feelings and mental state.

Figure 1: Examples of physical (green boxes), behavioural (blue boxes), psychological (purple boxes) and factors that are both behavioural and psychological (blue and purple box) that could be measured to further understand the welfare state for a mixed group of waterbirds in a zoological collection. This is not an exhaustive list of all factors that could be identified and measured. If such factors are described in a repeatable manner and used in a cyclic evaluation of welfare then individual bird reactions and responses to the environment they are in can be judged. For example, individual differences in personality will impact on responses to zoo visitors and to care givers and therefore welfare assessment should be considered on the individual animal level even for species that are commonly housed in groups. The feasibility of such a welfare assessment can appear tricky but leg rings or other markers or identifies can help match up animal behaviour with animal records and therefore provide a consistent picture of welfare across the course of a bird’s life in the zoo.

What we need to be able to do is balance these physical, behavioural and psychological measures and outputs of welfare (Figure 1) when designing the most appropriate style of enclosure and when deciding on what species of birds to include in our facilities’ collection plans. Afterall, each enclosure that is designed and constructed will be a compromise between the bird’s needs, what behaviours it is able to perform in full and the requirements of husbandry and care, plus how the animals are displayed to visitors. Relevant questions to be asked that can guide what to measure and why, when considering avian welfare in the captive wild animal facility are listed below:

• What is the relevance of flight to the species of bird being housed? i.e. how much time is spent flying per day or across different seasons for example?
• What sort of flight does the bird engage in, e.g. short flights that take place regularly between feeding patches, long distance travel to migrate between regions, nomadic moments that only occur when resources are depleted?
• Does the bird naturally feed on the wing?
• Is the bird cryptic or camouflaged or is flight or diving or running a main defensive/escape strategy?
• Is the bird a specialist or generalist feeder and therefore adaptable to a range of different ecological niches?
• Could the species feasibly fly in the same manner in captivity as in the wild within the confines of an enclosure that is logistically possible to construct?
• Does the species show specific responses to external stressors that could be used as indicators of negative behavioural expression? i.e. agitated, alarmed, uncomfortable, lethargic, disinterested.
• Are there specific resources that are essential for the complete performance of behaviour patterns in captivity? e.g. carotenoid pigments in the diets of flamingos.
• Can all life stages be successfully catered for?
• Is the social structure of the species in the wild able to be replicated within a zoo enclosure?

As a final example of what we should do for bird welfare, let’s consider this example of the domestic duck and what is currently explained in the literature. And then let’s see how the exotic duck species, housed in the zoo, can have its welfare assessment grounded in some aspects of domestic duck welfare guidelines that have been augmented by species-specific extra measures to consider. Table 1 provides examples of current welfare standards for domestic ducks in the UK (left column) and how these should be further developed, with new measures added, when considering non-domestic species of wildfowl in a non-agricultural setting.

It is clear from Table 1 that whilst agricultural standards for resource-based measures of welfare (i.e. input or provision to keep birds healthy) can be a useful starting point when considering what is needed for zoo species, the wide range of species housed and the individual needs of each species (based on their ecology and natural history) will mean that further measures should be taken in the facility. It is not enough to rely on agricultural welfare tools for domestic breeds when dealing with captive wild animal welfare. This is where more research into bird husbandry, population management and avicultural techniques used in the zoo would be helpful. Especially when coupled with research into what measures are best for inferring bird welfare (e.g. what behaviours to look for, what body language traits to record, and what physical health descriptors most accurately inform an underlying welfare state). Welfare assessment can only go so far in improving bird wellbeing if husbandry and management regimes are appropriate. If animal care protocols have not been assessed for their relevance to the species they are used for, then the results of any welfare audit are going to lack validity as the bird’s welfare state is always going to be sub-optimal if it is experiencing inappropriate daily care. Once again, this is where research is needed. Husbandry surveys, comparison of information on wild traits and natural history data need to form the core of husbandry guidelines used for bird species housed in captive facilities.

Ultimately, answering that age-old question “do birds like to fly” would be an enormous help to all of us attempting to infer welfare and improve husbandry accordingly. And the answering of that question is the challenge that I lay down to the avian welfare scientists of the future.

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