Migration ER Flashcards
Study on non-breeding partial migration species
Lundberg, 1985 - European blackbird (Turdus merula)
- Dominance behaviour, body weight and fat variation factors come into play in migration/remain choice
Study on breeding partial migration species
Gillis et al., 2008 - American Dipper (Cinclus mexicanus)
- Share winter grounds with residents but move to higher grounds to breed
- Not genetically determined (migrant or sedentary not always the same as parent behaviours)
Studies on skipped breeding migration species
Mortimer and Carr, 1987 - Green sea turtle (Chelonia mydas)
- Ascension island to Brazilian coast
Shaw and Levin, 2011
- Skipped thought to be related to risk vs reward
- Migration cost is high so those not fit enough skip migration to increase fecundity the following season
Studies into body size as an ecological driver
Belthoff and Gauthreaux, 1991 - house finches (Carpodacus mexicanus)
- Larger body size better suited for colder climates
Alonso et al., 2009 - Great bustards (Otis tarda)
- Opposite holds true, warmer climate suits smaller body size
Study into competitive release as an ecological driver
Mysterud et al., 2011 - Red deer (Cervus elaphus)
- migration to low elevation due to snow depth
- migration to high elevation associated with competition avoidance
Study into prior residency and early arrival as an ecological driver
Grayson et al., 2011 - Red spotted news (Notophtalmus viridescens)
- Males that are more likely to survive overwinter remain to ensure better reproductive chances in spring
- females remained if able to, to improve their reproductive capabilities due to decreased energy expenditure from migrating
- migrating females often skip reproductive seasons due to energy demands
Studies into predator vulnerability as an ecological driver
Hanson and Hylander, 2009 - Daphnia - DVM, smaller daphnia migrate to surface water while larger than 0.9mm remain sedentary as a result of predation risk - Using predator cue and visible light experiment found that proportion of migrants was always higher in <0.9mm than those that stayed but opposite was true >0.9mm. - Table: Size Migrate Stay .5-.7 83% 17% .7-.9 57% 43% .9 1.2 28% 72% 1.2-1.4 33% 67% 1.4-1.6 27% 73%
Skov et al., 2010 - Bream (Abramis brama)
- smallers at risk of predation so migrate
Study into fasting endurance as an ecological driver
Jahn et al., 2010 - Tropical kingbirds (Tyrannus melancholicus)
- Largest males most likely to migrate due to their higher energy requirments (insectivorous)
Study into importance of partial migration
Chapman et al., 2012 (Review)
- Two main roles nutrient transport and trophic importance
NT - Salmonids particularly important in nutrient transport
- marine derived nutrients carried upwards to freshwater, usually the result of adult fish death of egg deposition
- freshwater nutrients also transported to marine via salmonids
T - Many partially migratory fish are keystone or dominant species
- top-down effects (predator leaves, prey increases) e.g. cyprinids partial migration from lakes to streams affects lacustrine (lake) plankton dynamics
- may also affect predators both positively and negatively;
positive: migration may result in population boost due to increased reproductive rate
negative: decreased food at certain points of the year
Study into the positive aspect for predators in partial migration
Johnson, 1980
- co-existence with predators
- relatively unproductive large arctic lakes only support one large fish predator leading to a co-existence of predator and prey
Study into Blue tit competitive release
Smith and Nilsson, 1987
- Blue tit (Parus caeruleus)
- Juvenile females and juvenile males most likely to migrate
- adult females less so with adult males virtually never migrating
- down to a dominance hierarchy; adult males> adult females> juvenile males> juvenile females
- early hatched juvenile males less likely to migrate than late hatched males regardless of size, may be down to prior residency
