flight abilities
chickens can fly...sort of
Generally speaking, when we think about birds flying, our first thought is probably not of chickens. We probably think of migratory birds, such as Canada Geese, that fly across incredibly long distances. Or we might think of hummingbirds that can fly very fast in any direction. We may even think of the seagulls circling overhead, possibly trying to steal our sandwich or defecate on our freshly-washed cars. Chickens are capable of flying, however their abilities to do so are feeble compared to other species of birds.
Figure 6. Birds Flying High. Andrea Maria Hutegger, Jannuary, 2019. Explore Life. Retrieved on October 2, 2021 from https://www.explore-life.com/en/articles/birds-flying-high
Figure 10. Forget About The Road Why Are Chickens So Bad At Flying? Laura Geggel, December 8, 2018. Live Science. Retrieved on October 2, 2021 from https://www.livescience.com/57139-why-chickens-cannot-fly.html
Like other birds, chickens have flight feathers. There are two types of flight feathers the remiges and retrices. the Remiges are located on the wings and can be organized into primary, secondary, and tertiary groups; the retrices are located on the tail and help the bird control their movements in the air (The University of Waikato Te Whare Wānanga o Waikato, 2011). The flight feathers are well-depicted in Figure 11.
In a 2018 study titled "Flight Feather Development: Its Early Specialization In Embryogenesis", researchers analyzed skin samples from chickens in order to achieve a better understanding of how birds acquire their flight feathers. The researchers gathered samples from chickens' abdomens and flight feather formation (FFF) regions.
The researchers found that flight feathers begin developing at embryonic stages, before the chicken has even hatched! They also found that the feather buds in FFF regions invaginate through the skin and attach to bone tissues; this is described below in Figure 12 (Kondo et al, 2018).
Figure 11. Flight Feathers. The University of Waikato Te Whare Wānanga o Waikato, September 16, 2011. Science Learning Hub Pokapū Akoranga Pūtaiao. Retrieved on October 2, 2021, from https://static.sciencelearn.org.nz/images/images/000/000/305/embed/FLT_LKC_ART_05_FeathersAndFlight_flightfeathers_v03edited.png?1625097876
Figure 12. Deep invagination of the feather bud toward the bone primordium in the FFF region. a–h Sagittal sections of abdominal skin (a–d) and coronal sections of the FFF region (e–h) at E10 (a, e), E11 (b, f), E12 (c, g) and E13 (d, h). Arrowheads in (f) indicate the follicular cavity that starts invagination. i–l. Transverse sections of the FFF region showing the invagination process of the feather bud in the FFF region at E10 (i), E11 (j), E12 (k) and E13 (l). Scale bars: 100 μm. The blue core is the cartilaginous rudiment of the ulna, and the red layer surrounding the ulna cartilage is the ossifying bone collar. Kondo et al, January 16, 2018. Zoological Letters. Retrieved on October 2, 2021 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5771061/
But, it takes more than just flight feathers to be able to fly. According to an article from Live Science, "Birds need to have at least 1 square inch of wing per 0.6 ounces of body mass (1 square centimeter per 2.5 grams) to fly" meaning that there must be a balanced ratio of wing to body mass in order for a bird to be aerodynamic (Geggel, 2016).
This ratio is called wing loading, and as a result of selective breeding, chickens do not have sufficient wing loading to be aerodynamic. Chickens have too much body mass and too small of wings to support themselves in flight as efficiently as other bird species.
Figure 14. Can Chickens Fly? Kassandra Smith, June 4, 2020. Backyard Chicken Coops. Retrieved on October 2, 2021 from https://www.backyardchickencoops.com.au/blogs/learning-centre/can-chickens-fly
wing clipping further inhibits chickens' flight abilities
Wing clipping is the process of purposely cutting flight feathers on the wings to make them shorter; when done properly, this process is safe and painless to the bird. Although wing clipping is a common practice amongst bird owners, it can spark ethical complications and affect qualities of life.
In an article titled "Domestic Egg-laying Hens, Gallus gallus domesticus, Do Not Modulate Flapping Flight Performance In Response To Wing Condition", an experiment was performed to observe the consequences of clipping the wings of chickens. The experiment consisted of measuring the chickens' abilities to jump and fly downwards in a controlled environment. Some of the chickens had all of their flight feathers, some chickens had half of their flight feathers be clipped, and some chickens had all of their flight feathers be clipped (León et al, 2021). An example of each is shown below in Figure 14.
Figure 15. Wing clipping treatments of the hens against a solid background and a metre stick to measure fixed distance. (a) The unclipped hens retained all their primary and secondary feathers; (b) half-clipped hens had their 10 primary feathers clipped on each wing; (c) full-clipped hens had their primary and secondary feathers clipped on each wing. León et al, July 28, 2021. Royal Society Open Science. Retrieved on October 2, 2021 from https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8316787/
The study's results presented three main conclusions. Firstly, that wing clipping caused the chickens' wing load to increase. This was because shortening the flight feathers decreased the overall surface area of the chickens' wings. Next, the results showed that wing clipping did not have a significant effect of wingbeat amplitude, meaning that the chickens flapped their wings equivalently despite having or not having their flight feathers. Lastly, the study concluded that wing clipping did affect the chickens' descent velocity and descent angle (León et al, 2021).
it's okay to not be good at something
Sometimes chickens fail at flying. Sometimes they miss their landing. Other times chickens might slip or fall or collide with something as they attempt to fly. Chickens may be clumsy, but they are resilient!
Figure 16. The mean (± SE) percentages of each flight type (based on flight origin and ending) that ended in failed landings, presented for peak lay, mid lay and end lay in both flocks. Within each flock, data from single and double row sections were pooled together at each time point. PL = perch to litter, PP = perch to perch, LL = litter to litter, and LP = litter to perch. Only 1 instance of PP was recorded for Flock 1 (peak lay) with all other observations of PP seen in peak lay of Flock 2. The numbers above each bar indicate the total number of flights that were observed for each category of flights. Campbell et all, January 1, 2016. Poultry Science. Retrieved on October 2, 2021 from https://www.sciencedirect.com/science/article/pii/S0032579119321108?via%3Dihub
A recent study published in Volume 95 of Issue 1 of Poultry Science observed the landing success of flight attempts made chickens in aviary barns. Each barn was equipped with multiple tiers of cage structures proper necessities, so that the chickens had sufficient living conditions. The researchers observed four main types of flight activities and the time of day at which the flight attempts were made (Campbell et all, 2016).
Besides the internal structure of the chickens' enclosures, the researchers took into consideration the possibility of injury. The researchers were concerned about potential damage that failed flight attempts had made on the chickens' keel, which is a sternal bone perpendicular to the ribs. The article states, "observations coupled with keel palpations might determine if fractures play a role in flight reduction" (Campbell et all, 2016). This implies that if a chicken is in pain due to an injury, then the chicken is less likely to make a successful flight attempt.
look at them go!
