Brief description
Resource owners generally win contests against intruders, a phenomenon referred to as the 'Owner Advantage' (OA). Uca mjoebergi is a typical fiddler crab that is highly sociable, territorial and lives in mixed sex colonies on intertidal mudflats. Burrows are used in territory defence, for mating, and as refuge from predators and environmental stresses. Fights are common between owners and floating males who battle for ownership of the territory and burrow. Experiments were conducted from 28th Sept - 30 Dec 2006 at the lower reaches of Ludmilla Creek within East Point Reserve, 5km North of Darwin, NT. Previous experiments have revealed that owners win more contests than floaters because they are more motivated. This experiment was designed to test if owners are more motivated than floaters because they have invested more in neighbour relations. The results indicate that the total amount of time a male has been present in a territory did not affect his fighting succes. The amount of time he spent on the surface or with his burrow open represented the time he could interact with neighbours, had a marginally significant influence on fighting success. Establishing relations with neighbours appear to convey at least a small increase in motivation leading to a weak fighting advantage.Lineage
Maintenance and Update Frequency: notPlanned
Statement: Fights were documented and compared between owners with differing residency times and activity levels. Circular plots were marked out (diameter 55-65cm, n=11) on the mudflat and caged. Cages were made from mesh (6.5cm wide, 0.8cm mesh size), and clear plastic strips lined the top 4cm of the cage on the inside and outside. Cages were dug 1-2cm into the mud. To establish owners with known residency duratons I released and monitored individually marked males to the cages. The burrow was marked with a numbered flag, and the time recorded. Individually marked males were introduced repeatedly into plots for several days, creating plots with males with a range of known residency durations.
Fights were documented between newly introduced marked males and resident marked males (n=30). All losing males were removed to avoid pseudoreplication.
Residency duration were recorded for the owner, as was his activity. This information was grouped into four indices: 'cage duration' and 'residency duration' equate to tenure in the area, while 'open duration' and 'surface duration' were used as measures of neighbour relations.
Major claw length (manus+pollex) and carapace width of each male were measured to the nearest 0.1mm using dial callipers. Fight duration was timed using a handheld stopwatch and recorded to the nearest 0.01s after the event using a Sony Digital Video Camera.
Statement: Fights were documented between floaters and owners with residency durations of 10mins to 3days; this range encompases 85% of the variation in the population. A standard set of data was collected for each fight. For each fight the date, time, the type of floater, and winner were recorded. Additionally, all crabs were measured, and fight duration and phases recorded. The winner is the male that owns the territory at the end of a fight. The loser is the crab which walks away at the end of the fight. A fight was considered over when: a) the loser walked >30cm away, b) travelled past two other males territories, c) entered another burrow, or d) started another fight.
Residency duration were recorded for the owner, as was his activity. This information was grouped into four indices: 'cage duration' and 'residency duration' equate to tenure in the area, while 'open duration' and 'surface duration' were used as measures of neighbour relations.
Parameters: Datatype (1=field, 2=video), encounter ID, date, ltidet (time of diurnal low tide), hightideht (high tide height of the tide which follows the diurnal low tide), rtimet (time of the fight), ctype (condition, Res=resident), winner, cara (intruder carapace width - mm), chel (inturder cheliped / claw length - mm), ocara (owner carapace width - mm), ochel (owner cheliped / claw length -mm), actions observed (P=push, B=burrow, G=grapple, F=flick, D=dig, TB=true burrow fighting), dura (duration of fight - seconds), digdura (dig duration - seconds), cage duration (hrs), residency duration (hrs), open duration (hrs), surface duration (hrs), sizediff (size difference between owner and intruder claws - mm).
Notes
CreditFunded by The Ecological Society of Australia
Credit
Funded by The Australian Research Council (ARC)
Funded by The Australian Research Council (ARC)
Credit
The Australian National University (ANU)
The Australian National University (ANU)
Purpose
Previous experiments have revealed that owners win more contests than floaters because they are more motivated. This experiment was designed to test if owners are more motivated than floaters because they have invested more in neighbour relations.
Previous experiments have revealed that owners win more contests than floaters because they are more motivated. This experiment was designed to test if owners are more motivated than floaters because they have invested more in neighbour relations.
Issued: 07 08 2007
Data time period: 2006-09-28 to 2006-12-30
text: westlimit=130.5; southlimit=-13; eastlimit=131; northlimit=-12
text: uplimit=0; downlimit=0
Subjects
28960043 |
ANIMALS/INVERTEBRATES |
ARTHROPODS |
BIOLOGICAL CLASSIFICATION |
BIOSPHERE |
Biosphere | Ecological Dynamics | Competition |
Biosphere | Ecological Dynamics | Dominance |
COMMUNITY DYNAMICS |
Community Structure |
Crustaceans |
EARTH SCIENCE |
ECOLOGICAL DYNAMICS |
Fiddler crabs |
Neighbour Relations |
Owner Advantage |
Uca mjoebergi |
biota |
User Contributed Tags
Login to tag this record with meaningful keywords to make it easier to discover
Other Information
global : 637bba50-417e-11dc-aefb-00188b4c0af8
Identifiers
- global : b1a04bc0-447f-11dc-8cd0-00188b4c0af8
