20th International Congress of Arachnology

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108 DENVER MUSEUM OF NATURE & SCIENCE REPORTS | No. 3, July 2, 2016
Cushing
Student - oral presentation
Activity patterns and mating behaviors of
an arboreal tarantula: Avicularia laeta
*Joseph Hill, Cara Shillington
Eastern Michigan University, Department of Biology,
441 Mark Jefferson Science Complex, Ypsilanti,
Michigan 48197, USA
Tarantulas are sit-and-wait predators that remain close to
their retreat while hunting. Following an ultimate molt,
mature males travel in search of receptive adult females
and exhibit scramble competition, where males locate
scattered females within a habitat and show little aggres-
sion towards each other. Little is known about their daily
habits and behavioral ecology in their natural habitat;
especially for arboreal species. We examined several
aspects of the natural history of an arboreal tarantula
including: mate searching behaviors by males and activ-
ity patterns of juveniles and adult females. Retreats were
located and marked during the day based on the presence
of web and we returned at night to determine if retreats
were occupied. The diameter-at-breast height (DBH) and
length of visible silk was recorded. Active adult female
and juvenile retreats were observed nightly from twilight
until daybreak. Body position relative to their retreat was
recorded every 30 minutes. Wild-caught male tarantulas
were radio-tagged and released and these individuals were
re-located nightly and their position was recorded using a
GPS. These data were used to calculate distances travelled
per day and search areas. Adult females occupied trees
with a significantly larger DBH and longer visible silk
than juveniles. Both groups emerged from retreats around
the same time suggesting that light levels instigate activ-
ity. There was no difference in body position and proximity
to their retreats indicating similar daily behaviors. Several
males were relocated nightly on the same tree of an active
female suggesting that they remain within close proxim-
ity to sexually active females for extended periods. No
aggressive behavior was witnessed between mature-males
located on the same female retreat tree. The results of this
study provide the first insight into arboreal mature-male
tarantula searching behaviors and differences in retreat
site selection based on the size/age of an individual.
Keywords: tarantula, arboreal, mature-male, mating
Poster presentation
Social polymorphism in Anelosimus stu-
diosus: a longitudinal comparison
Maggie Hodge, Deborah Adeyemi
Louisiana School for Math, Science and the Arts 715
University Parkway, Natchitoches, LA 71457
Anelosimus studiosus is a subsocial theridiid whose
distribution ranges from the southeastern United States
through South America. Previous studies have shown
variation in social tendencies such that colony size and
lack of aggression increase from southern to northern
latitudes, not the typical pattern for social spiders.
Riechert & Jones (2008) examined social behavior along a
latitudinal gradient from southern Florida to central Ten-
nessee and found that social tolerance and multi-female
nests increased with latitude. Our study compared social
tendencies of a population of A. studiosus in northwestern
Louisiana to that found by Riechert & Jones at a compa-
rable latitude. Using the same behavioral assays we found
that the Louisiana population showed a significantly
greater proportion of social versus asocial phenotypes,
but a similar frequency of multi-female nests. This cor-
roborates that social polymorphism is characteristic of A.
studiosus and that it varies at the population level.
Keywords: subsocial spider, social polymorphism
Student - Oral presentation
Red list proposals of spiders for European
countries and regions
Fabian Hofmann, Daniel Gloor, Wolfgang Nentwig
University of Bern, Institute of Ecology and Evolu-
tion, Baltzerstrasse 6 3012, Bern, Switzerland
Only 11 of the 51 European countries have a national
red list for spiders comprising between 25 and 100%
of the national spider fauna. Fourteen countries have
other lists like conservation, governmental protection