1. Choosing Where to Live Chapter 8 or What side of the fence IS the grass greener on?

2. Choosing Habitats Fact: animals generally actively choose habitats, patches, etc. This is shaped by natural selection True or False Most animals have a instinctual ability to prefer proper habitat? True

3. Choice of Where to Feed, etc. no competition for food no depletion of food 20 J/hr10 J/hr Choose A Patch A Patch B

4. Ideal-Free Model of Habitat/Patch Choice Ideal – animals know everything about food Free – free to move anywhere Key points: 1. animals will have a preferred habitat 2. But will not necessarily choose that habitat (due to effects of competition). All organisms are identical with no fighting over resources.

5. Testing IFD with Fish Can vary food addition of feeders Assume maximizing fitness is maximizing rate of energy intake. At the IFD, all animals will have roughly equal energy intake rates.

6. Ideal Despotic Model of Habitat Choice It’s all about monopolizing resources Allow individuals to monopolize sites within habitats – ie. territories. Some individuals can defend high quality patches No longer “free” to go where you will. More realistic situation

7. Tested with Aphids on Cottonwood popular trees These aphids can reproduce asexually as clones or sexually. Sexually reproducing aphids are gall formers Females fight for position on leaf Best spot is at petiole of leaf 321321

8. 8.6 Poplar galls are occupied by poplar aphids

9. 8.8 Territories and reproductive success

10. Ideal Despotic Model 2 nd is worse than 1 st, but may be better if it is a big leaf. With 2 habitat patches – there are not always more on the best B A Chosen 1 st More individuals

11. Questions True or False The best habitats will always be entered first. True or False Will the best habitat always have the most individuals Depends on the size of the habitat and competition between individuals True

12. Reading Assignment pp249-263 What are the sexual differences in dispersal Contrast mammals vs. birds Why Voluntarily Disperse? Inbreeding avoidance Local competition How far to disperse? Out-breeding depression Avoidance of competition What factors might cause an animal to change breeding territories from one year to the next? What are the costs and benefits of long-distance migration? Migration in Monarch butterflies General natural history of migration Why do monarchs migrate all the way to Mexico? Dispersal Migration More discussion on these topics to come later

13. Territoriality Home range Area of activity Territory Exclusive area defended from intruders Questions to ask? Whether to be territorial? How to be territorial?

14. Benefits of Territoriality Reproduction Energy

15. Reproduction Remember the fighting aphids Removing others from leaf can allow a greater number of offspring Don’t fight due to cost in energy, time and injury. Birds No territory = no breeding for most birds Demonstrate many non-breeding floaters No territory Don’t fight for territory because they are young and can try to breed next year or the next Florida Scrub-Jays pages 117 - 124

16. Energy Territories outside of breeding season Only defending food (energy) Energy = fitness Seen in some birds and some mammals Ex. Nectar feeding birds (simple food source) Food source easily characterized and defendable

17. Golden-winged Sunbirds High quality territories are very beneficial to owners Stable food source Energy needs met in short time But not always territorial

18. Territorial sunbirds Flower Density - territories abandoned Cost to defend larger area is too high Flower Density - territories abandoned No net benefit, plenty of food Territoriality occurs at intermediate flower densities Intruders Rate - territories abandoned All time is spent defending

19. Territory Size Cost / Benefit Approach Minimal Territory Size m = metabolic cost of owner c = energetic cost of defending territory f = food density (or energy) (energy/m 2 ) Territory size (minimal) = (m+c)/f

20. Territory Size as a function of food 1/f Territory size Food density size α 1/f

21. Territory Size to Maximize Energy Gain Graphical model of optimal territory size. cost Benefit (can’t use it all) T1T1 T*T* T2T2 Territory Size Cost or Benefit T 1 = min territory size T 2 = max territory size T * = max energy gain (max = B-C) slopes are equal at this point - Break even when lines cross

22. Example Hummingbirds increase territory size before migration to gain weight In many cases, the environment may be saturated with territories that persist for long terms.

23. Effects on Territory Size When food density declines May be very little change in size Cost of expansion is too high Removing owners from their own territory When food density increases Could see small territory size But, re-expansion may be difficult Often see no change at all in size - stay as you are!!

24. Unchanging Size in Pied Wagtails Non-owners feed in nearby fields When food density in fields declines, they go to the river Owners cannot decrease or stop being territorial Owner lets only 1 intruder onto territory Satellite Helps with territory defense Stay 180° apart on opposite sides When intruder density decreases – satellite is removed. territory

25. Dispersal Costs Exposure to predators Requires energy Benefits 1)Inbreeding depression 2)Reduced mate competition

26. Inbreeding Depression Less likely for recessive genes to be expressed Females bear more of the energetic cost (avoid relatives) Males disperse to have more mates Female mammals hold territory and get help from another (ground squirrels), safe breeding den.

27. Mate competition Males fight – loser moves on to find another mate Not true for ground squirrels – happens before fighting Winning males move on to avoid sexually mature daughters Male lions leave (or forced out) when a new male comes into area

28. Bird Dispersal Males return when previous year was successful Disperse and move toward a more successful future if unsuccessful previous year

29. Migration Occurred gradually First with short range migrants Followed by long range migrants (continents)

30. 8.14 Short-range migration in the three-wattled bellbird (Part 2)

31. 8.15 Distribution of Catharus thrushes, a genus with both resident and migratory species (Part 1)

32. 8.20 The two migratory routes of Swainson’s thrush

33. Costs of Migration Energetic Predators – group dilution effect Cross Mediterranean at Spain – narrowest part Cross Atlantic when possible, if decreased body fat, go over to Mexico Black poll warbler – across Atlantic – shorter, few predators, and tail winds

34. Benefits of Migration Seasonality allows for bursts of food to support young Fish breed in freshwater Tropics – more food in freshwater Move to breeding ground (saltwater)

35. Monarch Butterflies Central Mexico Oyamel fir forest Less likely to have sudden freezes Moist and cool to maintain energy reserves Tree removal exposes them to rain and cold night sky Increased risk of freezing, exhaustion, and desiccation

36. 8.22 Habitat quality and survival of monarchs overwintering in central Mexico

37. Migrants and Non-migrants in Same Species Exactly the same fitness in the long run The 2 Strategy Hypothesis Differences are genetic Don’t change behavior from year to year Equal fitness on average Actually, individuals switch behaviors

38. Territoriality and Dominance Implies site-specific dominance Owner is dominant individual only on its territory Owner almost always wins in a dispute

39. Payoff Asymmetry Hypothesis Owner places a higher value on territory than an intruder will Owner is more willing to fight Intruder immediately retreats from Confrontation Intruder is looking for free territory

40. Example Capture territory owner male bird Hold it for a bit in an aviary Territory taken over by another individual (floater) Let it hold the territory for a few days Release original owner back into territory BIG FIGHT Original owner almost always wins eventually Not the case in butterflies.

41. Resource Holding Power Hypothesis Owner wins because they have superior ability to hold territory Territory owners are the best fighters Ex. Damselflies Fat reserves (not body size) dictate the winner in contest, more fit gets the territory.

42. Other Topics Domains Interspecific territoriality

43. Domains An incompletely defended territory Defend center stronger that edge/marginal territory Core Territory Tendency to evict intruders Distance from center

44. Interspecific territoriality One species defends territory against several other species. Unusual in nature Seen in territories during non-reproduction (ie. food defending territories) Aggression should be diet specific Mockingbirds run off other fruit eaters, but ignore insectivorous species.