1. Diet & Foraging Ciconiiformes Herons, bitterns & egrets,
[L. ciconia = stork]
Herons, bitterns & egrets,
ibises, spoonbills & storks
3 families, 116 species
Snowy Egret

2. Herons, egrets and bitterns
Ardeidae
Herons, egrets and bitterns
65 species
Cattle Egret

5. Great Blue Heron

6. Great Egret

7. Black-crowned Night Heron

8. Boat-billed Heron

9. Threskiornithidae
Ibises and spoonbills
32 species
African Spoonbill

11. White Ibis

12. Glossy Ibis

13. Ciconiidae
Storks
19 species
Saddlebill Stork

15. White Stork

16. Diet & Foraging Shape Life History Diet types Avoiding competition
Foraging efficiency

17. Generalists v Specialists
Stenophagous – highly restricted to a very limited number of food items
Euryphagous – eats a wide variety of foods

18. Lesser Flamingo eats only filamentous blue-green algae, Spirulina.
Thus monophagus with distribution limited by that of the algae

19. Ruffed Grouse, eats 300 different plant species and 100 different animal species in a single year

20. Animal-based diets are superior to plant-based diets in
Nutrient balance
Energy density
Digestibility

21. Food type. Availability of. % of families primarily. energy (%)
Food type Availability of % of families primarily energy (%) or regularly
consuming food type
Nectar
Meat & fish
Seeds
Insects
Other invertebrates
Fruit
Green plants, buds

23. Vertebrate prey
Highly digestible, basically protein & fat <2% carbohydrate
Nutritionally complete
50-80% water, many carnivores don’t need to drink
Proventriculus dominate

25. Insects
Adult insects are high in protein (50-70% dry matter) and lipid (5-35% dry matter), with low levels of nonchitin carbohydrate.
The amino acid balance of insects is almost as good as vertebrate prey and much better than plants.
Calcium is low, so egg-laying females often consume snail shells, bone fragments or egg shells.
Chitin, which is relatively indigestible, ranges from 18-60%.
Long, narrow beak.
Larger proventriculus and smaller gizzard than granivorous or herbivorous species.

27. Seeds Highest nutrient density of any plant part
High starch, sometimes high fat, moderate to low in protein
Low in calcium
Amino acid balance poor, many seed-eaters eat insects and feed young insects
Small seeds = high foraging time
Handling time high in species which hull seeds

29. Frugivores
Rank second to insects but only 11% of families are primarily fruit eaters most of which live in the tropics
Nutrient-dense v nutrient-dilute fruit

30. Nutrient-dense fruit Bayberry, mistletoe, dates, avocado
Large amounts of lipid (10-70%)
Moderate protein (5-20%)
Less water and sugar
Slow passage aids digestion

32. Nutrient-dilute fruit
High in indigestible skin and seeds
Pulp high in water & sugar, low in protein
Complete digestion gives too much energy too little protein

33. Skimming strategy Simple guts Fast passage = poor digestive efficiency
Maximize AA intake, limit sugar uptake
Cedar Waxwings process meal in 25 min

34. Nectarivores Large crops Short intestines & weak gizzard
Nectar mostly dilute sugar-water (20-25%) low in amino acids
All nectarivores eat insects to get AAs

35. Crimson-breasted flowerpecker, purple honeycreeper

36. facultative frugivory or facultative insectivory
Very few species consume a single food category throughout their adult life; e.g., obligate herbivore or obligate planktonivore
facultative frugivory or facultative insectivory

37. Seasonality

38. Avoiding competition

41. Close Relatives Avoid Competition by
Character displacement
Ecological segregation

42. Character displacement

45. Ecological Segregation
Blue Tit – small branches
Marsh Tit – large branches
Great Tit – ground

46. Niche Partitioning in North American Wood Warblers
Robert MacArthur

47. Cape May Warbler

48. Yellow-rumped Warbler

49. Black-throated Green Warbler

50. Blackburnian Warbler

51. Bay-breasted Warbler

53. Are birds sensitive to the net energy profit of their foraging effort?
Foraging Efficiency
Are birds sensitive to the net energy profit of their foraging effort?
Profit = energy gain – energy cost = J/sec
foraging time

54. White Wagtail Foraging – John Krebs
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