Lecture Exam 1

Question 1

1. What are feathers? What are they made of? What are their functions?

Answer 1

1. What are feathers? What are they made of? Modification of the outer skin, made of keratin, same protein as in hair and nails, non-living tissue that wears out easily and must be replaced. What are their functions? function as insulation for temperature regulation, and flight.

Question 2

2. In relative terms, describe the smell, vision, and hearing senses of birds.

Answer 2

smell~poorly developed, vision~ well developed; binocular vision in some, large eyes (15% weight of head), most have color vision and many see ultraviolet. Hearing also well developed.

Question 3

3. Describe how a bird’s wing differs from that of a pterosaur and that of a bat.

Answer 3

Birds use their entire forelimb for flight, pterosaurs used a single finger, and bats use their hand.

Question 4

4. Approximately how many species of birds are there and approximately what percentage of the earth’s species are birds?

Answer 4

~10,000 species of birds, make up about 0.6% of life on Earth

Question 5

5. What percentage of birds are threatened with extinction?

Answer 5

~12%

Question 6

6. What are five reasons birds make good biological subjects?

Answer 6

1. Very visible
   • Most are diurnal, conspicuous, and approachable
   • Can color band them for individual recognition
2. Widely distributed
3. Species level taxonomy is well know
4. Geographic distributions well known
5. Very diverse

Question 7

7. What is the smallest extant species of bird? What is the largest extant species of bird?

Answer 7

Smallest bird: Bee Hummingbird; 1.6 grams, 2.5 inches

Largest extant bird; Ostrich; up to 345 lbs.;up to 9 ft. tall

Question 8

1. In class, we talked about 10 common habitats found in San Diego County. Please list 5 of these.

Answer 8

1. Coastal Salt Marsh / Tidal Mudflat
2. Coastal Sage-Scrub
3. Chaparral
4. Southern Oak Woodland
5. Coniferous Forest
6. Pinyon-Juniper Woodland
7. Desert Scrub
8. Riparian Woodland
9. Grassland
10. Urban/Suburban/Agricultural

Question 9

2. For each of the following habitat types, please list three bird species that are typically found in this type of habitat:Coastal Salt Marsh, Coastal Sage-scrub, Chaparral, Southern Oak Woodland, Coniferous Forest, Pinyon-Juniper Woodland, Desert, Riparian Woodland, Grassland, Urban/Suburban/Agriculture.

Answer 9

1. Coastal Salt Marsh / Tidal Mudflat~Clapper Rail, shorebirds (Short-billed Dowitcher), waterfowl (Redhead), Belding’s Savannah Sparrow
2. Coastal Sage-Scrub~Rufous-crowned Sparrow, California Gnatcatcher, Cactus Wren
3. Chaparral ~Spotted Towhee, California Thrasher, Wrentit, Western Scrub-Jay
4. Southern Oak Woodland~Oak Titmouse, Bushtit, White-breasted Nuthatch, Acorn Woodpecker
5. Coniferous Forest~Steller’s Jay, Band-tailed Pigeon, Mountain Chickadee, Pygmy Nuthatch, Dark-eyed Junco
6. Pinyon-Juniper Woodland~ California Thrasher, Black-throated Sparrow, Rock Wren, Black-chinned Sparrow
7. Desert Scrub~Nashville Warbler, Greater Roadrunner, Cactus Wren
8. Riparian Woodland~Brown-headed Cowbird, Bullock’s Oriole, Warbling Vireo
9. Grassland~Western Meadowlark, Lazuli Bunting, Loggerhead Shrike
10. Urban/Suburban/Agricultural~Rock Pigeon, Anna’s Hummingbird, Common Raven

Question 10

3. Arrange the following San Diego County habitats in order from West to East:
   Chaparral, Pinyon-Juniper Woodland, Desert Scrub, Coastal Salt Marsh, Southern Oak Woodland, Coastal Sage Scrub, Coniferous Forest

Answer 10

1. Coastal Salt Marsh / Tidal Mudflat
2. Coastal Sage-Scrub
3. Chaparral
4. Southern Oak Woodland
5. Coniferous Forest
6. Pinyon-Juniper Woodland
7. Desert Scrub
8. Riparian Woodland
9. Grassland
10. Urban/Suburban/Agricultural

Question 11

4. If given a diagram of a transect showing a cross section from west to east through San Diego county, be able to label the location of the following habitat types: coastal salt marsh, coastal sage-scrub, chaparral, oak woodland, coniferous forest, pinyon-juniper, and desert scrub

Answer 11

1. Coastal Salt Marsh / Tidal Mudflat
2. Coastal Sage-Scrub
3. Chaparral
4. Southern Oak Woodland
5. Coniferous Forest
6. Pinyon-Juniper Woodland
7. Desert Scrub
8. Riparian Woodland
9. Grassland
10. Urban/Suburban/Agricultural

Question 12

5. List six kinds of information that are used in the field to help identify a bird to species.

Answer 12

1. Know what species to expect beforehand.
– Geographic location 
– Seasonal Occurrence 
– Habitat
2. Vocalizations
3. Behavior
– What’s the posture? 
– Does it walk?
– How does it fly?
– Solitary or alone?
- Behavior 
4. What is the size of the bird?
– Use familiar birds as landmarks (ex., sparrow, robin, crow, hawk)
5. What is the shape/proportion of the bird?
– head small compared to body? Tail shape, wing shape, bill shape, etc.
6. Field Marks

Question 13

1. List the four types of similarity among organisms discussed in class.

Answer 13

1. Common ancestry 2. Convergence 3. Reversal 4. Shared primitive characters

Question 14

2. What is homology? Give an example of homology in birds.

Answer 14

Homology is a similarity due to common ancestry where a species inherits a trait that evolved in its common ancestor. The character state is shared and derived. An example of homology in birds is a forelimb being capable of powered flight evolving from a grasping forelimb.

Question 15

3. Define and give an example of convergence discussed in class.

Answer 15

Convergence is the independent evolution of a similar character in two or more lineages. An example of similarity due to convergence is seen in sunbirds, honeycreepers, and hummingbirds → all feed on nectar and have thin bills but are not closely related.

Question 16

4. In class, I gave an examples of convergence (nectar feeding birds). Using birds found in San Diego County, come up with your own example of convergent evolution. (Hint: think of things you learned in the first lab)

Answer 16

The Whimbrel and California Thrasher both evolved decurved bills for feeding OR the Caspian Tern and Barn Swallow both evolved forked tails for better ability to maneuver in the air to catch prey.

Question 17

5. Define Reversal and give an example discussed in class.

Answer 17

Reversal is reversion to an ancestral form of character due to selection or mutation. An example is the hoatzin whose young have claws on their wings.(?) The first bird, Archaeopteryx, had claws → most birds have no claws → present- day hoatzin has claws.

Question 18

6. What is homoplasy?

Answer 18

Homoplasy is similarity due to convergence AND reversal.

Question 19

7. Contrast Homoplasy and Homology. Which is useful for building phylogenies?

Answer 19

Homology is similarity due to common ancestry. This is useful for building phylogenies whereas homoplasy is not useful.

Question 20

8. Define monophyletic group.

Answer 20

Monophyletic groups consist of a common ancestor and all of its descendants. AKA a clade.

Question 21

9. Give an example of a monophyletic group.

Answer 21

The group Tetrapoda which consists of amphibians, mammals, reptiles, and their common ancestor.

Question 22

10. Draw a phylogenetic tree showing the accepted relationships among these groups: fish, amphibian, mammals, lizards, snakes, birds, crocodiles.

Answer 22

Crocs and birds form a monophyletic group and are sister to snakes and lizards. Then mammals are sister to these, then amphibians, and then fish.

Question 23

11. Why are birds considered a type of reptile? (use the terms monophyletic group and paraphyletic group in your answer).

Answer 23

Birds are considered a type of reptile because the class Reptilia is monophyletic if you include the birds whereas without the birds, Class Reptilia is a paraphyletic group, and we shouldn’t name paraphyletic groups.

Question 24

12. List the three main lineages of Archosaurs. What is a synapomorphy for Archosaurs?

Answer 24

The three main lineages of Archosaurs are dinosaurs, crocodiles, and pterosaurs. They all share the synapomorphy of antorbital fenestrae which is a pair of openings between the eye and the nose.

Question 25

13. What is a synapomorphy (shared, derived character) for Dinosaurs? How does the hindlimb of the pelvic girdle of dinosaurs differ from other reptiles?

Answer 25

The synapomorphy for Dinosaurs is a hole in the hip socket. The hindlimb of the pelvic girdle extends down vertically instead of outwards horizontally.

Question 26

14. Describe what the crescent-shaped carpal bone allowed Maniraptors to do.

Answer 26

It allowed for side to side movement as well as up and down movement.

Question 27

15. What was the functional precursor to the avian flight stroke?

Answer 27

The predatory stroke of the maniraptor

Question 28

16. In class, we talked about several species of non-avian dinosaurs that had feathers. Name one of these and describe what type of feathers it had and where these feathers were located.

Answer 28

The Microraptor had feathers attached to its forelimbs, hindlimbs, and tail. The feather vane was asymmetrical which indicates an aerodynamic function, most likely for gliding.

Question 29

17. Name a non-avian dinosaur that had asymmetrical feather vanes. What is the significance of the asymmetrical shape?

Answer 29

Microraptor; the asymmetrical shape indicates an aerodynamic function.

Question 30

18. What is the evidence that feathers evolved first for insulation rather than for flight?

Answer 30

Feathers have been found in at least 9 species of non-bird dinosaurs which suggests that they probably evolved for insulation or signaling/communication function rather than for flight.

Question 31

19. List four “avian” characters that evolved in Maniraptor relatives of birds, before the evolution of birds.

Answer 31

Feathers, the flight stroke, the furcula, and parental care.

Question 32

20. Why are birds considered a type of dinosaur? (use the terms monophyletic group and paraphyletic group in your answer).

Answer 32

Dinosaurs are a paraphyletic group unless you include the birds so the Order Dinosauria is only monophyletic if it includes the birds. Thus, birds are considered Dinosaurs.

Question 33

21. List three synapomorphies of Aves.

Answer 33

1. Powered flight using entire forelimb 2. Quadratojugal contacts squamosal 3. Less than 26 caudal vertebrae

Question 34

22. List five characters of Archaeopteryx that are pleisiomorphic relative to modern birds.

Answer 34

1. Teeth, curved backwards 2. Numerous unfused caudal vertebrae 3. Snout, rather than bill 4. No keel or sternum 5. Claws on end of digits of forelimb

Question 35

23. List four synapomorphies of Archaeopteryx and modern birds.

Answer 35

1. Powered flight using entire forelimb 2. Wing feathers divided into primaries and secondaries 3. Fused clavicle → furcula 4. Partially fused metatarsals

Question 36

24. For each of the following scientists, describe their ideas concerning the origin birds and the relationships of birds to other reptiles: Huxley, Heilmann, Ostrom, and Padian & Gauthier. Draw a phylogeny for each to illustrate their ideas.

Answer 36

24. For each of the following scientists, describe their ideas concerning the origin birds and the relationships of birds to other reptiles: Huxley, Heilmann, Ostrom, and Padian & Gauthier. Draw a phylogeny for each to illustrate their ideas.
    Heilmann (1927): “Thecodont Hypothesis”; Danish illustrator and scientist; published influential book: “The Origin of Birds”; surveyed the anatomy of dinosaurs, pterosaurs, crocs, and birds → concluded that birds are related to reptiles, but are not particularly close to dinosaurs. His argument was that the furcula which was found in Thecodonts (primitive animals with not a lot of specializations) and birds but not in dinosaurs could not have evolved in Thecodonts, been lost in dinosaurs, and then evolved in birds. His hypothesis was very persuasive and reigned for 40 years. *Thecodonts not a monophyletic group here

Ostrom (1970s): Discovered a new theropod in 1964 → Deinonychus: shared 16 skeletal features with Archaeopteryx and other birds; proposed that birds are the sister taxon to Coelurosaurian dinosaurs.
Padian & Gauthier (1980s): Used modern systematics (phylogenetic systematics, cladistics) to put Ostrom’s findings in a specific phylogenetic context; Birds are actually a type of Coelurosaur, not just related to them. In fact, they are a maniraptor. This is the most accepted and prevailing viewpoint among scientists today.
*For his version of phylogeny, see last page (his taxa is the same one we use in class)

Question 37

25. Distinguish between the Arboreal and Cursorial theories of the origin of bird flight. For each theory, be sure to include the following information in your answer: Where did the immediate ancestor live? Describe the scenario for each theory as outlined in class. For what purpose did feathers originally evolve? Which theory on bird origins is each associated with? Which requires the fewest assumptions?

Answer 37

Arboreal (“Trees-down”) Theory: The immediate ancestor lived in trees. Scenario: bipedal cursorial → leaping between trees → parachuting → gliding → active flight
Feathers originally evolved for flight. Associate with the “Thecodont hypothesis” of bird origins.
Cursorial (“Ground-up”) Theory: The immediate ancestor: ground dwelling. Scenario: cursorial, balance and prey capture assisted by long arms → running with flapping → powered flight. Feathers originally evolved for something other than flight, possibly thermoregulation. This theory requires fewer assumptions because fossils exist with these features, there are many adaptations for flight already present. Most accepted hypothesis.

Question 38

26. In living birds, how do young birds use their wings before they can fly? What can this tell us about the origin of bird flight?

Answer 38

Young birds use their wings to aid in running up inclined surfaces. Further evidence for “ground-up” flight theory. (Wing-assisted inclined running)

Question 39

27. On the phylogeny shown on the last page of this document, circle the clade on the phylogeny that contains the birds (Aves).

Answer 39

See last page, Archosaur Phylogeny.

Question 40

28. On the phylogeny shown on the last page of this document, be able to match each of the following synapomorphies to the arrow indicating where it evolved on the tree:
    antorbital openings, fused tarsometatarsus, keeled sternum, carpometacarpus, strut-like coracoid, pygostyle, grasping hand, furcula, hole in hip socket, powered flight using the entire forelimb, semilunate carpal, relatively long arms, 3-toed hind foot, synsacrum with 8 or more vertebrae

Answer 40

See last page, Archosaur Phylogeny.

Question 41

29. If given a timeline showing the last 500 million years of the planet’s history, be a
    ble to draw four arrows to indicate each of the following: 1. When life first moved onto land,
30. when dinosaurs and mammals first evolved,
31. when the first bird evolved, and
32. when modern humans first evolved

Answer 41

1. When life first moved onto land (terrestrial life, 400 mya)
2. when dinosaurs and mammals first evolved (230 - 200 mya),
3. when the first bird evolved (Archaeopteryx, 140 mya), and
4. when modern humans first evolved (300,000 - 100,000 years ago).

Question 42

1. Provide a definition for the Vicariant type of Allopatric speciation.

Answer 42

Vicariant: population is divided into two widespread populations by a physical barrier

Question 43

2. Provide a definition for Allopatric Speciation by Peripatric speciation.

Answer 43

Peripatric: a colony disperses from a widespread population to a new area and evolves reproductive isolation.

Question 44

3. Contrast Vicariant Speciation with Peripatric Speciation.

Answer 44

Vicariant involves a physical barrier, does not occur because of dispersal, and usually results in 2 equal-sized populations. Peripatric involves a physical barrier as well, does involve dispersal, and usually results in 1 larger and 1 smaller population.

Question 45

5. Define Hybrid Zone

Answer 45

Hybrid zone: a region in which genetically distinct populations come into contact and produce offspring of mixed ancestry

Question 46

8. Define the Biological Species Concept

Answer 46

Species are actually or potentially interbreeding populations that are reproductively isolated from other such group

Question 47

9. Define the Phylogenetic Species Concept.

Answer 47

– the smallest diagnosable cluster of organisms within which there is a parental pattern of ancestry and descent (Cracraft 1989)

Question 48

10. List three criticisms of the Biological Species Concept.

Answer 48

1. evolution happens prior to reproductive isolation
2. if isolated populations don’t overlap, you can’t test the BSC
3. Doesn’t account for asexual organisms
4. can’t be applied to fossil forms
5. not useful in plant groups where speciation by hybridization is common

Question 49

11. List three criticisms of the Phylogenetic Species Concept.

Answer 49

1. phylogenies are difficult to obtain
2. species specific trait may be “trivial”
3. will name too many species

Question 50

12. What is the criterion used in the Biological Species Concept? What is the criterion used in the phylogenetic species concept?

Answer 50

Reproductive isolation= BSC

Monophyly=PSC

Question 51

13. What is the role of subspecies in the Biological Species Concept? the Phylogenetic Species Concept?

Answer 51

A subspecies in a set of populations that share one or more distinctive features and occupy a different geographical region; There are many subspecies named under the BSC, but the PSC does not recognize subspecies, species is the smallest evolutionary unit.

Question 52

14. Describe the situation with the Brown Towhee discussed in class. How many species are there under the Biological Species Concept? Why? How many species are there under the Phylogenetic Species Concept? Why?

Answer 52

There are two distinct populations that are slightly divergent morphologically and their ranges do not overlap. Under the BSC they would probably be considered one species, and under the PSC 2 different species.

Question 53

15. The Yellow-rumped Warbler is widespread throughout North America. It occurs in two morphologically distinct forms. The eastern form, sometimes called the “Myrtle Warbler”, has a yellow crown, yellow rump, and a white throat. The western form, sometimes called “Audubon’s Warbler”, is similar in plumage except it has a yellow throat. The two forms also differ in vocalizations and other aspects of behavior.
Given your knowledge of species concepts, how many species are there? In your answer, be sure to identify which of the two species concepts discussed in class you will be using. Also, be sure also to define the concept when defending your answer. You will also need to identify what other kind of data or information you would need to make your decision (how would you test your hypothesis?) Note: we did not discuss this in class, but you should still be able to come up with a good answer based on your knowledge of species concepts.

Answer 53

If using the biological species concept to determine the number of species, reproductive isolation should be considered. Because the ranges of these two forms do not overlap, you can use calls from one population and play them in the other to see how the females and males react and determine if mating would even seem possible. If the females are attracted to the call and the males do not seem to react violently, then mating might seem possible. Considering the two forms have different vocalizations and other behavior, I would assume they would be considered two different species under the biological species concept, or maybe even two subspecies of the same species.

Question 54

16. Describe the situation with the “Northern Oriole” complex. Where are the different forms found and what do they look like? Does hybridization occur? If so, where and among which forms? Draw the phylogeny for the forms involved. What does the phylogeny indicate in relation to the taxa that hybridize? How many species do you think are involved? Justify your answer based on a particular species concept. Be sure you define the species concept you are using in your answer.

Answer 54

Two different populations of the Northern Oriole complex exist, one in the Western US down into Mexico (Bullock’s Oriole) and the other in Eastern US (Baltimore Oriole). The population in the west has a streaked back, and the one in the east has a black back. There are also other differences in the colors; western population is more yellow, while the eastern have orange. The populations meet in the Great Plains and there is some overlap of populations and hybridization is very common in this area. Under the Biological species concept these two populations would be considered one species because there is hybridization and no reproductive isolation. However, if a phylogeny is drawn, the two populations do not form a monophyletic group. Therefore, under the phylogenetic species concept, where monophyly is the criteria, these two populations would be considered two different species. From this, it can be determined that the ability to interbreed is possibly an ancestral character.

Question 55

17. Describe the situation with the “Northern Flicker” complex. Where are the different forms found and what do they look like? Does hybridization occur? If so, where and among which forms? Draw the phylogeny for the forms involved. What does the phylogeny indicate in relation to the taxa that hybridize? How many species do you think are involved? Justify your answer based on a particular species concept. Be sure to specify and define the species concept you are using

Answer 55

The different forms of the Northern Flicker occur all over the US and down into Mexico. The ones in the West side of the US have red in their wings and tails. The ones in the east side of the US look the same, but have yellow in their wings and tail feathers except for red. The other morph (gilded) exists primarily in Mexico but ranges up into the Southern US, in AZ and CA. The red-shafted and yellow-shafted freely hybridize and the red-shafted and gilded rarely hybridize. The phylogeny is below and it shows that the yellow-shafted and the red-shafted are actually not as closely related as the gilded and the red-shafted are to each other. Because of this data, I would suggest using the phylogenetic species concept and calling the three different morphs with different ranges 3 different species. If using the biological species concept they would only be considered 2 different species, because of the common hybridization that occurs between the red and yellow-shafted. The phylogeny below shows the relationships and also shows that the mating that occurs between the red and yellow-shafted Flickers may be an ancestral trait that they haven’t lost yet.

Question 56

18. What is an evolutionarily significant unit?

Answer 56

Original definition, Ryder (1986): populations that actually represent significant adaptive variation based on concordance between sets of data derived from different techniques.
Moritz (1994) definition: Populations that are reciprocally monophyletic for mtDNA alleles and show significant divergence of allele frequencies at nuclear loci.
ESU designed to preserve important evolutionary distinctiveness; preserve the potential to continue to evolve.

Crandall et al. (2000):
There are two components to an ESU:!

1. historical and reproductive isolation 2. Adaptive distinctiveness

Moritz is only concerned only with #1

Question 57

19. Under Moritz’s definition of an ESU, how many ESUs are there of the California Gnatcatcher? What is the evidence to support this? What are the implications of
    this for management of the species? What other factors might be considered?

Answer 57

Moritz is only concerned with historical and reproductive isolation to consider something an evolutionary significant unit. The California Gnatcatcher showed no distinctive differences in genetic data, so under his definition they would all be considered one species. The implications for this are that they may not be considered high priority any more for conservation. Other factors that might be considered for this study would be the ecological distinctiveness the Gnatcatchers in California have that is different from all of the other populations that are down into South America.

Question 58

1. What are four components of a bird’s bill?

Answer 58

maxilla, mandible, jaw muscles, & rhamphotheca (keratin sheath)

Question 59

2. Pick one of the birds we have seen on our field trips and describe how its feet and bill are adapted for its particular diet.

Answer 59

Nuttall’s Woodpecker: Zygodactyl feet for climbing trees vertically. Pointed, chiseled bill for extracting insects from inside the wood.
Ducks: Webbed feet for swimming along the water. Depressed (flat) bill for filtering out food particles from the water.
Songbirds: Anisodactyl feet for perching in trees. Large bills crack seeds and smaller bills for insects or fruit.

Question 60

3. What are Rictal Bristles?

Answer 60

Stiff, hair-like feathers projecting from the base of the bill of birds that catch insects

Near the tip of the feather, only a stiffened rachis, no barb

Question 61

4. Name three possible functions of Rictal Bristles.

Answer 61

may help funnel prey
protect eyes
sensory function

Question 62

5. Describe how the tongues of nectar feeders are adapted to their diet.

Answer 62

Bananaquit tongue: Forked with fine, brush-like hairs. Good for absorbing nectar and fruit juices
Hummingbird tongue: Forked at tip; Curved, making a hollow channel through which the bird sucks nectar

Question 63

6. Give two adaptations of the woodpecker tongue that reflect its diet.

Answer 63

Very long hyoid apparatus, allows the tongue to reach deep into tree trunks
Barbs
Saliva of woodpeckers is sticky (good for extracting insects)

Question 64

7. Describe the tongue of the Northern Shoveler and indicate how it is adapted to the bird’s diet.

Answer 64

The tongue has long bristles on the sides for filtering water that comes through the tip of the bill. The food is fed to the middle of the tongue to the back of the throat. Excess water is expelled at the sides/base of the bill after passing over the bristles.

Question 65

7. How is the saliva of woodpeckers adapted to their prey preference?

Answer 65

Woodpecker saliva is sticky to more easily extract insects.

Question 66

8. Describe how flamingos feed.

Answer 66

Bird holds bill upside down, swinging it side to side and moving the head forward
Tongue and throat pump water into mouth
Water and contents pass over numerous hair-like plates of the bill; food particles are strained

Question 67

9. Where is the avian crop located? What is its function?

Answer 67

Crop: permanent, expanded section of the esophagus
Function: storage area; also softens food and regulates its flow through the digestive tract

Question 68

10. How is the crop of the hoatzin adapted to its unique diet?

Answer 68

Crop of Hoatzin - thick-walled, muscular, and large; crop actually grinds the food and begins the first stage of digestion through bacterial fermentation (like a cow)

Question 69

11. What are the two parts of the avian stomach? Where are they located in relationship to each other? What are their functions?

Answer 69

Proventriculus - the anterior portion
Function: secrete acidic gastric juices and peptic benzymes, creating a favorable chemical environment for digestion
Gizzard: the posterior part of the stomach
Function: grinding and digesting tough food

Question 70

12. What is the function of the proventriculus?

Answer 70

Function: secrete acidic gastric juices and peptic benzymes, creating a favorable chemical environment for digestion

Question 71

13. What is the function of the gizzard?

Answer 71

Function: grinding and digesting tough food

Question 72

14. What are ceca? Where are they located? What is their function? In what types of birds are they prominent?

Answer 72

Ceca (singular, Cecum): pair of pouches extending from the junction between the small and large intestine
Function: hold material longer while bacteria in the ceca further break it down; it is then released to the large intestine
Lots of variation among species
More prominent in ground-dwelling and flightless birds; absent or poorly developed in arboreal birds

Question 73

15. What is the cloaca?

Answer 73

Cloaca: Common chamber that receives the feces from the large intestine, urine from the kidneys, and eggs or sperm from the gonads

Question 74

16. Describe how some of the unique adaptations of the avian digestive system are the result of the evolution of flight.

Answer 74

Rhamphotheca instead of teeth
Crop: Store food on the go (don’t have to hold the food in its mouth)
Gizzard: Grinds food the same way mammalian molars do
Together, these adaptations offer birds the option of eating the food they find later. Some locations where a bird finds food can be dangerous so they can just gobble up the food without chewing it (swallow it whole) and possibly regurgitate the food for their young. Carrying the food in their mouth can be cumbersome in flight.

Question 75

17. Define Niche.

Answer 75

Niche: ecological role, specific biotic and abiotic requirements of a species

Question 76

18. What is the competitive exclusion principle?

Answer 76

CEP: No two species can occupy the same niche in the same space and time

Question 77

19. Describe Robert MacArthur’s study of foraging behavior of warblers and indicate how it supports the competitive exclusion principle.

Answer 77

1958: In a single tree, all the warblers are present, but each one spent its time the most in only certain areas of the tree, always at different times. They never occupy the same space (niche) as another at a given time. (CEP)

Question 78

20. Describe how the competitive exclusion principle might apply to shorebirds at the San Diego River Flood Control Channel. Please note that “shorebirds” is a general term that applies to plovers, sandpipers, stilts, and avocets. Be sure to include specific examples of exact species we observed in your answer. You will also want to define what the competitive exclusion principle is in your answer.

Answer 78

While sandpipers and plovers spend a lot of time in close proximity foraging for food, they each are limited to depth of probing. Sandpipers have longer bills than plovers and can forage food deeper from the ground. Sandpipers and plovers fill different niches because they get food from different sources.
Similarly, Stilts and Avocets fill a different niche because they have long legs. They are able to wade into deeper water to forage for food and can reach even deeper into mud than sandpipers.

Question 79

21. Describe how the competitive exclusion principle might apply to waterfowl (different species of ducks, grebes, coots) at the San Diego River Flood Control Channel. Be sure to include specific examples of exact species we observed in your answer. You will also want to define what the competitive exclusion principle is in your answer.

Answer 79

Ducks and coots generally forage in shallower water while grebes dive in deeper water. Grebes also mainly feed on fish while ducks feed a lot on vegetation or seeds. Grebe fill a different niche than ducks and grebes. Grebes are different than ducks because they can feed on not just vegetation but small invertebrates. When ducks are filling the niche for feeding on vegetation, grebes have the option to forage for a different food.

Question 80

22. In lab, you learned the main foraging behavior for Common San Diego Birds. Be able to define each of these foraging behaviors (see the lab handout for the definitions). The foraging behaviors you need to define include: ground glean, foliage glean, bark glean, hover and glean, hover and pounce, hawks, aerial foraging, aerial pursuit, swoops, high patrol, low patrol, high dives, skims, surface dips, surface dives, dabbles, stalk and strike, & probe.

Answer 80

ground glean: picking up items from the ground surface
foliage glean: picking items from foliage and occasionally branches
bark glean: picking items off tree trunks and branches, only rarely includes removal of invertebrates from foliage as will. Includes excavating and drilling into bark
hover and glean: Takes nectar, insects, or berries from plants above ground while hovering
hover and pounce: Hovering before swooping or dropping on prey
hawks: sallies from perch on short flights to capture flying insects. Often returns to same perch.
aerial foraging: While in prolonged, continuous flight, captures flying insects. “Screens” insect out of the air.
aerial pursuit: Chases and catches birds in the air. Drops on flying birds from above, killing them in midair with a blow from the talons. Also may snatch them from perches.
swoops: Snatches up prey in low searching flight
high patrol: Soars at high altitude in search of carrion or prey
low patrol: Seeks prey in low searching flight.
high dives: Drops from height into water, usually to catch fish, but sometimes to take waterfowl or other prey
skims: Flies low over water and snatches up fishes and aquatic invertebrates
surface dips: Takes food from the water’s surface or from just below while floating or swimming on the surface
surface dives: Floats and then dives; swims underwater using feet and/or wings
dabbles: Floating on surface in shallow water, pivots headfirst downward while raising hindquarters above water to reach submerged plants or animals on or near the substrate (mud, sand)
stalk and strike: Hunting by standing motionless on bank or in water and spearing fishes, frogs, etc.
probe: Foraging for food beneath the surface of the substrate (mud, sand) either in or near shallow water.