Senses and Reproduction

Question 1

monocular and binocular vision

Answer 1

Monocular vision and its association with wide visual fi elds allows birds to detect motion and potential predators for their survival. Behavioral studies indicate that many avian species prefer monocular vision for fi xating and inspecting distant objects, as indicated by them turning their heads sideways to the object
- Binocular vision is excellent for depth perception, and thus, judging distance, as the input from both eyes is needed to compute the distance of a visual target

Question 2

nicitating membrane

Answer 2

ransparent/translucent third eyelid that lies beneath the other two eyelids. It can be rapidly swept across the eye to clear the surface of the eye of any debris and to moisten the eye

Question 3

size of avian eyes, importance of head movement, color vision, UV vision

Answer 3

• avian eyes constitute a much greater volume of the bird’s head than in mammals (+50%)
• ostrich eyes are bigger than elephants
• not as spherical as humans
• rod cells absorb light (more in owls)
• cone cells see color can detect more shades

Question 4

visual acuity and rate of assimilation

Answer 4

most birds can resolve the details of an image that is about three times further away from them in distance than we can

Question 5

ability to detect motion

Answer 5

birds can easily detect the distinct flashing of of a fl uorescent light bulb oscillating at 60 hertz, while we would see continuous light.

Question 6

hearing-resolving ability

Answer 6

-better than humans

Question 7

large variation between species in the sense of smell

Answer 7

• turkey vultures detect decaying flesh miles away

- majority of birds (songbirds) poorly developed sense of smell

Question 8

limited taste ability in birds, specific appetite for salt

Answer 8

• no well developed sense of taste, but meant to encourage ingestion of nutrients, to discriminate among foods, and to avoid those that are toxic
• if they need salt, they will pick it out from various foods

Question 9

respiration; syrinx, air sacs

Answer 9

• vocalizations are created by the syrinx which is made of membranes and muscle (voice box part of airways)
• most birds have 9-11 air sacs that fill the entire body cavity

Question 10

why birds are so efficient in extracting oxygen from air compared to humans (just in general terms)

Answer 10

• air sacs allow birds to have air 100% of the time

- lungs are extracting all the time, and it is an active process

Question 11

the fact that birds occupy every kind of ecological niche and have evolved different strategies (senses, beak structure, use of tools and other animals, etc.) to thrive in these niches when it comes to acquiring food - be able to give examples

Answer 11

• can use sense of touch to clamp down beak in 1/25th millisecond if feel something
• toucans have large beaks which are good for reaching into nests to eat birds
• can use rocks to break eggs to suck out nutrients
• cowbird follows livestock and eats insects on ground

Question 12

function of the crop, gizzard, ceca, small intestine, proventriculus, large intestine

Answer 12

• the crop is the site of storage and first place of chemical digestion
• the second phase of chemical digestion is in the proventriculus or glandular stomach where pepsin works
• the gizzard is the site of mechanical digestion (seed eaters have muscular gizzards)
• the small intestine is the third phase of chemical digestion (mixed with lots of enzymes)
• the large intestine is primarily a site for water and electrolyte absorption

Question 13

potential sites (digestive organs) for bacterial fermentation of ingested leafy plant material

Answer 13

• The function of intestinal ceca is the further digestion and fermentation of food particles, in particular leafy plant material. This material is digested through the action of cecal secretions, bacteria, and fungi. Water, digested nutrients, and fermentation end products such as volatile fatty acids are absorbed across the ceca

Question 14

terms ovoviviparous, oviparous

Answer 14

• done within the female but mother’s blood doesn’t nourish the offspring. Young are nourished by yolk from the eggs.
• done outside the mother’s body. Young are nourished by nutrients contained in an encased egg. ALL BIRDS

Question 15

reproduction in birds is seasonal

Answer 15

• wild species lay eggs and hatch young at a time of year which will maximize the chance of offspring survival
• it takes some weeks for the gonads to grow from the regressed, non-functional condition to fully functional
• seasonal cues that regulate the reproductive cycle need to be reliable predictors of the “best” time to reproduce

Question 16

cues for reproduction

Answer 16

• long-term = changing photoperiod is a good example
• medium-term = adequate food supply, territory
• short-term = nest site, mate, courtship
• can be perceived by sensory organs or act directly on brain
• all must be right or will be blocked

Question 17

the fact that female birds can store sperm (why is it important)

Answer 17

helps sperm undergo biochemical transformations

- so it will be ready when they lay an egg

Question 18

functions of the ovary and oviduct

Answer 18

• ovary has gamete multiplication, gamete maturation, hormone production, and nutrient storage, hormone storage, ovulation, and control of ovipositon
• oviduct refers to the whole tubular reproductive tract of the female and captures the ovulated ovum, transports and expulses it, stores spermatozoa, site of fertilization, site of early embryo development, secretion of albumen, encasement of ovum, addition of fluids, secretion of shell, secretion of cuticle, expulsion (oviposition)

Question 19

male reproductive characteristics (why internal testes, lack of a penis in most birds, quick maturation of sperm, and production of a lot sperm compared to other animals such as humans or farm animals)

Answer 19

• two testes
• internally located
• massive seasonal growth of testes followed by regression in size
• quicker sperm maturation because of higher temp internally, but higher mortality rate, but produces a lot more sperm

Question 20

reasons for birds laying eggs with specks of color

Answer 20

help parents recognize their own eggs, and predators

Question 21

determinate vs. indeterminate egg layers

Answer 21

• some species lay a fixed number of eggs per breeding season and then stop laying (determinate)
• other species will continue to lay for long periods if eggs are removed from the nest (indeterminate)

Question 22

major components of the egg (yolk, albumen, and shell)

Answer 22

• yolk is one big cell that contains half the proteins. Nutrient source
• Albumen is the major water reservoir for the egg and contains about half of the total protein content of the egg. It also has about one third of the mineral content of the egg. Th e protein constituents of albumen, besides providing amino acid building blocks for the growth of the developing embryo, also serve vital functions in protecting the egg from bacterial invasion
• shell has pores for gas exchange and is made of calcium carbonate

Question 23

how birds attract mates, female selection

Answer 23

tail ornamentation, choose sperm

Question 24

different strategies for incubation including brood parasitism

Answer 24

• females of one species lays eggs in the nest of another species and the host incubates them (in 80 species)
• male may hold one egg on feet and keep warm by abdominal contact
• may be buried in decaying vegetation

Question 25

why some birds are polygamous

Answer 25

• single parents
• food considerations
• territory considerations
• have more birds bring food back to babies

Question 26

precocious vs. altricious chicks

Answer 26

• precocious chicks have feathers when they hatch, eyes are functional, and they have walking locomotion. can leave nest within 24 hours. may not have parental contact. nutients used for locomotion and warmth
• altricious chicks are hatched naked, blind, and completely dependent on parents. nutrients used for growth

Question 27

survival after hatch - why parents kill babies, or why siblings kill each other, why are these babies produced

Answer 27

not enough food