Territoriality. Environmental factors and territory size in kites. Environmental factors and territory size in kites

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1 Territoriality, Habitat Selection, and Aggression Territoriality When is it beneficial? 1. When limited resources are clumped and ephemeral? 2. When limited resources are uniformly distributed in time and space? Environmental factors and territory size in kites Research question: What factors affect the size of a territory? (Dunk & Cooper 1994) Hypothesis: The density of resources and the density of competitors affect territory size Prediction: Territory size will decline with an increase in resource density or competitors Environmental factors and territory size in kites Methods: White-tailed kites (Elanus leucurus) Uniquely marked individuals Recorded feeding territory size Estimated abundance of food items (voles) Estimated abundance of avian competitors for food (hawks, kites, falcons, and owls)

2 Environmental factors and territory size in kites Results: Territory size declined with increasing competitor abundance Territory size declined with increasing number of voles Conclusion: Both competitor abundance and food density affect territory size in kites Habitat Selection Most animals have habitat preferences Natural selection has lead to the evolution of species matched to particular environments Kirtland s warbler Habitat Preferences Endangered Breeds only in jack pine N lower peninsula - MI Nests eclusively beneath young jack pines (5-20ft) Well-drained, sandy soils Conspecific density can influence reproductive success in a preferred habitat. Good Fair Poor The reproductive success of individuals in highly preferred and less preferred habitats may be the same (on average) if the density in preferred habitats is high.

3 Resource availability and the presence of others influence habitat selection Ideal free distribution model assumes: Individuals attempt to maimize fitness Habitat locations differ in resources Fitness is negatively density-dependent Individuals are equal competitors Individuals are free to move at no cost The ideal free distribution model IFD predictions: 1. Individuals will settle in habitats based on the relative fitness payoffs: the number of individuals in each habitat will be proportional to habitat quality 2. All individuals will have the same fitness no matter where they settle Habitat preference in aphids Habitat preference in aphids Territorial poplar aphid Each spring, 1000s of females compete to form galls on the midribs of poplar leaves Preferred position is at the base of a large leaf Inferior competitors must make the best of their bad situation Smaller, unoccupied leaf? 2 nd gall on larger, occupied leaf? parthenogenic The reproductive success of the second colonist on medium and large leaves is essentially the same as that of a single aphid on a small leaf

4 Since habitat preferences are adaptive, individuals inhabiting prime real estate usually have greater reproductive success Source habitats Better quality Better competitors Population grows natality>mortality Sink habitats Poorer quality Poorer competitors Population declines natality<mortality Population replenished via immigration from source habitats Conspecific attraction Conspecific attraction Individuals prefer to settle near others Two hypotheses: 1. Allee effect: when population size is low, fitness increases with density 2. Conspecific cueing: the presence of another is a cue to a high-quality location (Dias 1996) From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, 2014 by Oford University Press Allee Effect Why might it be advantageous for animals to choose to live in an area with a higher density of conspecifics? Why might it be advantageous for animals to choose to live in an area with a higher density of conspecifics? 1. Mate access it can be difficult to find a mate at low population densities 2. Cooperative defense more eyes, Selfish herd, Dilution effect 3. Cooperative feeding learning about resources, eavesdropping on the location of food group hunting - access to larger prey 4. Environmental conditioning / habitat alteration

5 Why did focal males prefer the occupied bush? From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, 2014 by Oford University Press Conspecific cueing in American redstarts Research question: How do male American redstarts select habitat patches? (Hahn & Silverman 2006) Hypothesis: Conspecific cueing is used to find and settle on territories Prediction: Newly settling birds (yearlings and immigrants) will use the presence of singing males as a cue to the location of high-quality habitat for settling, while returning males will not Conspecific cueing in American redstarts Methods: American redstart (Setophaga ruticilla) Captured and banded birds on 12 plots Si treatment plots played conspecific song Si control plots played no song Surveyed each plot four times per week to record the arrival of males, along with their age and status (returning or immigrant)

6 Conspecific cueing in American redstarts Results: New immigrants strongly preferred playback plots Returning adults and yearlings showed no preference Conclusion: Conspecific attraction is an important mechanism for habitat selection for older immigrant males Conspecific cueing in American redstarts Why might returning adults not show a preference for plots with calling males? and yearlings? The density and behavior of conspecifics can affect an individual s: Territory size Habitat selection Fighting behavior

7 Why don t animals simply to try to kill their rivals? Let s play a game! You are all male elephant seals. Let s battle! You will interact with 5 other students one at a time Each time, you decide whether to fight or flee If you both fight determine the winner by playing rock-paper-scissors Winner: 10 points Loser: -10 points If one of you fights and the other flees Fighter wins 10 points Fleer: wins 0 points, no cost If you both flee, play rock-paper-scissors. Winner: 10 points Loser: wins 0 points, no cost Now a female is watching If you both fight determine the winner by playing rock-paper-scissors Winner: 50 points Loser: -10 points If one of you fights and the other flees Fighter wins 50 points Fleer wins 0 points If you both flee, play rock-paper-scissors. Winner: 30 points Loser: 0 points, no cost

8 Now you are all male elephants with huge tusks If you both fight determine the winner by playing rock-paper-scissors Winner: 10 points Loser: -50 points If one of you fights and the other flees Fighter wins 10 points Fleer wins 0 points, pays no cost If you both flee, play rock-paper-scissors. The decisions of opponents and resource value affect fighting behavior -dove model Game theory model used to understand variation in fighting behavior Assumes two strategies: hawk (fight until victory or injury) and dove (never fight but uses low-cost display) s for an individual depend on the strategy of the opponent, along with the benefits and costs of fighting Predicts an evolutionary stable strategy (ESS): both hawks and doves eist in a population with equal fitness Winner: 10 points Loser: wins 0 points, pays no cost - Model - Model 0.5 (B-C) B What would happen if a hawk tries to invade a population of all doves? 0.5 (B-C) B B B

9 - Model - Model What would happen if a dove tries to invade a population of all hawks? assume C > B 0.5 (B-C) B What would happen if a dove tries to invade a population of all hawks? what if B > C? 0.5 (B-C) B B B The decisions of opponents and resource value affect fighting behavior Sequential assessment model Game theory model used to understand fighting Individuals can ehibit many different strategies, not just hawk and dove Individuals assess the relative fighting ability of their opponent The predicted ESS behavior: fight as long as the potential benefit of winning eceeds the cost of continuing to fight Low-cost behaviors should be used early in fights Fights between evenly matched opponents will last longer than fights between unequally matched opponents From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, 2014 by Oford University Press

10 Salamander fights for mates Research question: What affects the duration of fights between male salamanders? (Verrell 1986) Hypothesis: The size (value) of a female affects male fighting behavior Prediction: Males will fight longer for larger (more fecund) females From Nordell and Valone, Animal Behavior: Concepts, Methods, and Applications, 2014 by Oford University Press Salamander fights for mates Methods: Red-spotted newts (Notophthalmus viridescens) Staged encounters between size-matched males over a female Recorded the duration of wrestling between the males Salamander fights for mates Results: The duration of wrestling was positively correlated with female body length Conclusion: The value of a resource affects fighting duration in red-spotted newts

11 If you had to bet on who will win a fight, the territory owner or an intruder, which one would you bet on? a. Territory owner b. Intruder