Paul Rose is a Lecturer in Animal Behavior at the University of Exeter. He is also a Research Associate for WWT, managing the Animal Welfare & Ethics Committee. Paul is co-chairing BIAZA’s Research Committee and the ICUN Flamingo Specialist Group. He also teaches at University Centre Sparsholt on the MSc Applied Zoo Biology. Since 2000, he has been involved with captive animal research.

Progressive zoos are improving how they conduct welfare assessments and aiming to create environments that promote positive well-being for their animals. Although it is difficult to know what animals think and feel, it is possible to infer animal welfare for certain species more accurately than others. For example, higher mammals like chimpanzees ( pan troglodytes), and gorillas (gorillas) are extensively studied. We now better understand their social structure, life history, evolutionary relationships, and behavioral ecology. We can identify their high-motivated behaviors and make behavioral decisions to promote positive welfare states. This information can be used to assess the suitability of housing, farming, and population management for species under human care.

However, many other species are kept in captive wild animal facilities, making it more challenging to assess welfare. Birds are one of the most taxonomically varied animal groups found in zoos. It is not easy to determine bird welfare. Birds are endotherms like mammals. However, they have many traits in common with their reptilian ancestors and complex physiology and anatomy. Many birds also fly in ways that are not typical of mammals (flight), using vertical and air spaces in a manner other species can’t. They have complex reproductive behaviors, many different mating systems, and different strategies for raising their young. It’s not surprising that many tools we use to assess welfare in mammals are difficult to translate for birds.

Birds do not have facial expressions, so emotions and moods cannot be seen in the same way as mammals. It is possible to see body language, posture, and orientation to express psychological well-being and underlying emotions. Birds will conceal signs of stress and illness to avoid potential predators. Bird carers must be able to spot signs of disease and stress in their birds and intervene if necessary.

Captivity can limit what birds can do. Understanding their behavioral needs, choice, and environmental control is crucial in assessing welfare. The environment in which the birds are kept will restrict their ability to fly, regardless of how large or small. It would help if you considered your bird’s needs when considering a flight. Do we know? When looking at welfare systems. If flamingos are kept in covered aviaries, they can keep their flight feathers. But will they be able to fly in a meaningful manner? Would their behavior be better if kept in an open enclosure but not flight-restrained? Because it is less likely that pest species will enter its environment, the flamingo’s health and well-being may be better in a covered aviary. It is also more biosecure and can provide easier farming (e.g., As there is no way for other birds to compete for food, the flamingos are protected from each other. The flight-restrained flamingos in the open enclosure and fully-winged birds in the aviary will still have control and choice over their movements and where they go. The possibility of birds flying into the netting and collisions with the aviary structures may impact the welfare of the flamingos in the covered aviary.

The well-being and behavior of flamingos that spend most of their time on the ground, such as egrets and spoonbills, are greatly improved by covered aviary housing. This allows them to fly freely and can perch off the bottom. For spoonbills and egrets, which breed in trees and perch on waterside vegetation, they shouldn’t be restricted from flying, for example. An enclosure designed for one species might not be appropriate for another, even though they may have similar ecology, anatomy, and ways of life.

Many of the welfare programs I’ve mentioned so far are resource-based. They are inputs we give to animals, and we assess the effectiveness of these inputs based on birds’ behaviors. It is also essential to consider the underlying emotional aspects that affect welfare. These are the outputs of the environment the animal is currently living in. These dynamic aspects are often called “animal-based measures.” These welfare measures are more difficult to define and describe consistently and solidly. Bird keepers need to do more work identifying emotional outputs (personality characteristics or body language descriptions). This could help them assess the bird’s mental and emotional state.

Figure 1: Examples of physical (green boxes), behavioral (blue boxes), psychological (purple boxes), and factors that are both behavioral and psychological (blue and purple boxes) that could be measured to further understand the welfare state for a mixed group of waterbirds in a zoological collection. This is a partial list of all factors that could be identified and measured. If such aspects are described in a repeatable manner and used in a cyclic evaluation of welfare, then individual bird reactions and responses to their environment can be judged. For example, individual personality differences will impact zoo visitors’ and caregivers’ responses. Therefore welfare assessment should be considered on the personal animal level, even for species commonly housed in groups. The feasibility of such a welfare assessment can appear tricky. Still, leg rings or other markers or identities can help match up animal behavior with animal records and therefore provide a consistent picture of welfare across the course of a bird’s life in the zoo.

When designing an enclosure or deciding which species to include in the facility’s collection plans, we must be able to balance these behavioral, psychological and physical measures. Each section must balance the bird’s needs and ability to perform its full range of behaviors. It also has to consider how visitors view the animals. Below are some questions you should ask to help guide your decision-making about what measurements to make and how to measure them.

• How vital is the flight for the bird species being housed? i.e., How much time do you spend flying each day or in different seasons?
• What type of flight does the bird take, e.g., Are there short flights between feeding spots, long-distance migration between regions, or nomadic moments when resources are scarce?
• Is the bird able to eat on its wing naturally?
• Are the birds camouflaged and cryptic, or do they fly or dive? What is their primary escape/defensive strategy?
• Are they specialist birds or generalist feeders, and are they able to adapt to different ecological niches?
• Can the species fly in captivity the same way as they do in the wild?
• Is there any evidence that the species exhibits negative responses to stressors? i.e., agitated, alarmed, uncomfortable, lazy, disinterested.
• Is there a specific resource that is essential to the performance of certain behavior patterns in captivity, such as, e.g. e.g., Carotenoid pigments in the diets of flamingos
• Are all stages of life possible to be covered?
• Can the social structure of the species found in nature be reproduced in a zoo?

Let’s take the example of the domestic duck as an example of what we should be doing for bird welfare. This is what the literature currently explains. Let’s look at how exotic duck species can be assessed for interest in a zoo. Additional species-specific measures have enhanced these aspects. Table 1 shows examples of UK welfare standards for domestic ducks (left column), and how they should be developed with new measures when considering wildfowl species in non-agricultural settings.

Table 1 shows that agricultural standards are not suitable for resource-based welfare measures (i.e., table 1 shows that agricultural standards for resource-based welfare (i.e., input or provision to maintain birds’ health) may be helpful as a starting point for considering the needs of zoo species. However, the extensive range of species and their individual needs (based on their ecology and history) will require additional measures to be taken at the facility. When it comes to wild animal welfare in captivity, it is not enough that we rely solely on agricultural welfare tools. More research on bird husbandry, population management, and farming techniques in the zoo is needed. This is especially true when combined with research into the best methods to infer bird welfare (e.g., What behaviors should be looked for, what body language traits should be recorded, and which physical health descriptors best inform an underlying welfare status? If the husbandry and management of birds are appropriate, welfare assessment can help improve bird well-being. Any welfare audit will be invalid if the protocols for animal care are not suitable for the species they are being used for. The bird’s welfare status will always be poor if it receives insufficient daily care. This is why research is essential. The core of the husbandry guidelines for birds housed in captivity facilities must be based on husbandry surveys and comparisons of wild traits and natural history data.

Answering the age-old question, “Do birds like to fly?” would greatly help those trying to infer welfare and improve farming. The challenge is what I am putting forward to future avian welfare scientists.

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