1. Pantropical (except Australia)
Demography
Trogoniformes
1 family (Trogonidae)
39 species
Pantropical (except Australia)
Cavity-nesters
Elegant Trogon

2.
Distribution of trogon species. Numbers = species.

3. Elegant Trogon, formerly Coppery-tailed Trogon.
Trogon (from the Greek meaning “gnawer”; Gruson 1972) refers to their hooked, dentate bill, used in grasping insects and fruit. Trogons also hover to pick insects or fruit off trees.

4. Elegant Trogon at nest in Sycamore Tree.

5. Old World trogons (three species in Africa, eleven in Asia)

6. Whitehead’s Trogon - Borneo

7. Red plumage is unusual, quickly fading in museum specimens.

8. Trogons eat fruit and large insects.

9. Cuban Trogon

10. Resplendent Quetzal, Central America’s most attractive trogon.

12. Note tail feathers sticking out of nest hole.

13. The study of populations, their structure, status, and trends
Demography
The study of populations, their structure, status, and trends

14. Exponential increase
A single pair of Robins would increase to 24 million Robins in 10 years if all offspring survived and bred.
Population increase of House Finches following introduction in eastern U.S.

15. Numerous forces counter this tendency as illustrated in Leopold’s figure. Leopold’s figure shows the population stabilizing at a constant size. This is an idealized situation. Stable population size is probably uncommon. Golden eagle populations fluctuated no more than ± 15% from the long-term mean over several decades in England (Newton 1998:6). Many populations fluctuate with time. Long-term studies are required to document population changes. See Figure illustrating six long-term studies.
carrying capacity

16. Population Limitation v Population Regulation

17. Population limitation
Suitable habitat
Nest sites
Food
Natural enemies (predators, parasites, diseases

18. Population regulation
Density-dependent changes in birth rates & death rates serve to
stabilize populations

19. Density-dependent population regulation
Density-dependent population regulation in Black-throated Blue Warblers at Hubbard Brook Exp’tl Forest, New Hampshire. (A) population stable over 30 years at about 10 adults/10 hectares. (B) Population growth rate is lower in years of high abundance. (c) Annual fecundity declined as the density of breeding adults increased. Numbers next to dots in Fig. C are years.
Black-throated Blue Warbler

20. Great Tit

21. Great Tit

22. Stable population size is probably uncommon
Stable population size is probably uncommon. Golden eagle populations fluctuated no more than ± 15% from the long-term mean over several decades in England (Newton 1998:6). Most populations fluctuate with time.

23. Figure 1. 2 (p 7) from Newton, I. 1998. Population limitation in birds
Figure 1.2 (p 7) from Newton, I Population limitation in birds. Academic Press: London.

24. White Storks in Baden-Wurttemberg, Germany
White Storks in Baden-Wurttemberg, Germany. Shags on Isle of May, Scotland increase then leveled off , but with large annual fluctuations.

25. Great Tits in The Netherlands exhibit irregular annual fluctuations superimposed on a long-term increase. Grey Heron population in Britain declined following harsh winters (arrows).
Grey

26. Bearded Tits in southern England declined following cold winters (arrows). Regular population cycles in Red Grouse result from nematode infections.

27. Prime demography variables
Survival = probability of living to a particular age
Fecundity = number of young produced per year

28. A balance between fecundity and survival

29. (A) Age-specific fecundity (number of fledglings per year) versus annual mortality. Short-lived species (high annual mortality) must produce many young during each of their few breeding attempts if the population is to remain stable (Figure 17-2, Gill 3th ed). (B) Age at maturity (first breeding) decreases in short-lived species.

30. Mortality and fecundity are strongly influenced by body size

31. Larger species tend to Live longer Be older at 1st breeding
Have longer breeding cycles
Produce fewer young per breeding effort

32. 1st breed when 8-12 years old 1 egg per clutch
Live > 50 years
1st breed when 8-12 years old
1 egg per clutch
1 young every other year
Live 8 years max (2 on average)
1st breed when 1 year old
10-12 eggs per clutch
Up to 2 clutches/year
Royal Albatross
Large albatrosses are 8-12 years old when they first breed. Laysan and Royal Albatrosses may live over 50 years.
Blue Tit

33. Areas under the curves are the same
Areas under the curves are the same. Life-time reproduction is the same in small species and large. Fig. 8-3 (p 8-6) Handbook of bird biology.

34. Adult mortality is inversely related to body size
3% per year in Royal Albatross
70% per year in Blue Tit
Large albatrosses are 8-12 years old when they first breed. Laysan and Royal Albatrosses may live over 50 years. Adelie Penguins, mortality of breeders is 39%, nonbreeders 22%. Adelies first breed when 3 years old. 75% of females die during their first breeding attempt. Mortality only 10% in 11 year old Adelies.

37. Average annual adult mortality

38. Survival Large species > small species Seabirds > land birds
Tropical species > temperate species

39. Common Terns weigh 120 grams, versus 170 grams for a California Quail or Yellow-billed Magpie. Much smaller than a 450-g Common Crow.

40. Common Terns on Cape Cod
Breeding population age structure of Common Terns (a seabird) on Cape Cod.

41. Age-specific survival Probability of survival is low the 1st year
Great Tit example

42. Great Tit life-table

43. Percentage of juveniles eaten annually
Great Tit %
Blue Tit %
P 513, Gill.
Eurasian Sparrowhawk
Long-term study at Wytham Wood, Oxford, England

44. Age-specific survivorship
Long thought to remain constant throughout adult life

45. Survivorship of adults averages 78% per year
Florida Scrub Jay, p 513 Gill
Survivorship of adults averages 78% per year
Florida Scrub Jay exhibits constant mortality after the first year.

46. Annual survival changes with age in some species

47. Eastern Screech Owl Age % adult (yrs) survival 49 58 61 67 75 7-10 75
From Table Gill, F.B Ornithology 3nd edition. Data for suburban owls.

50. P 442-444. Newton, I. 1989. Lifetime reproduction in birds
P Newton, I Lifetime reproduction in birds. Academic Press: London
Only 3% of individuals in one generation of fledglings produce 50% of the next generation of fledglings

51. Sources of adult mortality
Annual survival rates
Males 51% Females 40%
83% of annual mortality occurred on migration
Low mortality on breeding grounds and on wintering grounds

52. “As a rule, bird populations seem to be limited by food scarcity during the nonbreeding season.” Gill p 554

53. Aftermath of ice storm. Freezing rain coats everything with ice making it impossible for birds to find food. Small birds’ fat reserves last only 2-3 days at low temperatures.

54. High population density Low population density
Great Tit over winter survival

55. Distribution of Eastern Phoebe