By Emily Bachert, Rachel Gunn and Tanya Dewey
Geographic Range
Great reed warblers are migratory. Beginning in April and through the summer months, great reed warblers are found in northern Europe, especially the southern central region of Sweden. During the rest of the year, they migrate to the tropical regions of western Africa. (Gale Group, 2002; Hansson, Bensch, and Hasselquist, 2004)
Biogeographic Regions:
palearctic 
(native ); ethiopian (native ).
Habitat
(656 to 2296 ft)
Great reed warblers are typically found near water, swamps and streams, in reed beds and other vegetation. (Gale Group, 2002)
These animals are found in the following types of habitat:
temperate ; terrestrial .
Terrestrial Biomes:
savanna or grassland .
Aquatic Biomes:
lakes and ponds.
Other:
riparian .
Physical Description
(0.74 to 1.8 oz)
(7.48 to 7.87 in)
(10.24 in)
Great reed warblers are one of the larger warblers with masses of 21 to 51 grams and a typical length of 20 centimeters. The wings are long and rather pointed at the end. They have a brown color above and a whiter shade on the underbelly. (Gale Group, 2002)
Some key physical features:
endothermic ; homoiothermic; bilateral symmetry .
Sexual dimorphism: sexes alike.
Reproduction
Great reed warblers breed seasonally, number of clutches attempted per breeding season is not reported.
Breeding occurs from April to early August in Europe and in the winter in parts of Africa.
Many male great reed warblers are monogamous and polygynous. Females choose their mate partially on the quality of their territory, males with high quality territories tend to be polygynous. Females tend to choose territories in accordance with food abundance and based on nest site quality. Attractive territories also have less risk of nest predation. Males with lower quality nesting territories are monogamous or fail to mate. Polygynous males provide less parental care. Males also warn females by giving alarm calls when predators approach.Females also choose mates based on their song repertoire, which predicts reproductive success. Hasselquist et al. (1996) noted that females copulate with males other than their first mate only when that male has a greater song repertoire, resulting in extra-pair copulations. By engaging in extra-pair copulation, females are seeking benefits for their offspring since the fledgling survival is positively related to the father's song repertoire size. (Hansson, Bensch, and Hasselquist, 2000; Hasselquist, Bensch, and von Schantz, 1996; Nowicki et al., 2000)
Mating systems:
monogamous ; polygynous .
Great reed warblers breed from early April through August in northern Europe and during the winter in parts of Africa. An average of three to six eggs per season are laid. Nestlings hatch after 14 days of incubation. Great reed warblers mate in reed beds of marshes and lakes. (Hansson, Bensch, and Hasselquist, 2004)
Key reproductive features:
iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; oviparous .
Females are responsible for building the nest and provide most of the parental care. The main contribution from the males is in protection of the nesting area from predators. Polygynous males help provide food for the offspring only for his first mate. Secondary mates must provide for their offspring on their own. Monogamous males provide food for the offspring. (Hansson, Bensch, and Hasselquist, 2000)
Parental investment:
altricial ; pre-fertilization (provisioning, protecting: female); pre-hatching/birth (provisioning: female, protecting: male, female); pre-weaning/fledging (provisioning: male, female, protecting: male, female).
Lifespan/Longevity
Little information is available on the lifespan of great reed warblers. They may live an average of 2.4 years in the wild.
Behavior
Great reed warblers are migratory, moving seasonally between Europe in the summer and sub-Saharan Africa in the winter. They are active during the day. (Gale Group, 2002; Hansson, Bensch, and Hasselquist, 2004)
Home Range
Home range size is not reported in the literature.
Communication and Perception
Males sing songs of two varieties, one for attraction of females and the other for defending their territory. The mate attraction song lasts around four seconds. The territorial defense call is about one second in length. With these short territorial defense calls they are able to warn off other males without interrupting their other calls. (Price, 2008)
Communicates with:
acoustic .
Food Habits
Great reed warblers have a varied, mainly carnivorous diet. They usually eat insects and spiders. Some fruits are eaten in the non-breeding season. They have also been observed eating snails, small fish, and frogs. Male warblers bring food to nesting females. (Gale Group, 2002)
Primary Diet:
carnivore (insectivore , eats non-insect arthropods).
Animal Foods:
amphibians; fish; insects; terrestrial non-insect arthropods; mollusks.
Plant Foods:
fruit.
Predation
- western marsh harriers (Circus aeruginosus)
- water rails (Rallus aquaticus)
- bitterns (Botaurinae)
Great reed warblers emit alarm calls when they detect predators, such as marsh harriers. Bitterns and water rails are predators of eggs and nestlings. Other predators are not known. Great reed warblers are vigilant against predators and their cryptic coloration may help avoid predation. (Hansson, Bensch, and Hasselquist, 2000)
Anti-predator adaptations::
cryptic .
Ecosystem Roles
Great reed warblers impact their ecosystem by dispersing seeds and eating insects. Their nests are sometimes parasitized by common cuckoos (Cuculus canorus). They are susceptible to plasmodium infection. (Bensch et al., 2008)
Key ways these animals impact their ecosystem:
disperses seeds; creates habitat.
- Plasmodium ashfordi
- common cuckoos (Cuculus canorus)
Economic Importance for Humans: Negative
There are no known adverse effects of great reed warblers on humans.
Economic Importance for Humans: Positive
Great reed warblers are appreciated by bird enthusiasts for their songs and mimicry.
Conservation Status
IUCN Red List: [link]:
Not Evaluated.
US Migratory Bird Act: [link]:
No special status.
US Federal List: [link]:
No special status.
CITES: [link]:
No special status.
State of Michigan List: [link]:
No special status.
Assessed in 2008, IUCN classifies great reed warblers as "least concern." The IUCN estimates a population size of 2,900,000 to 5,700,000 individuals. ("Acrocephalus arundinaceus", 2008)
For More Information
Find Acrocephalus arundinaceus information at
Contributors
Emily Bachert (author), Centre College. Rachel Gunn (author), Centre College. Stephanie Fabritius (editor, instructor), Centre College. Tanya Dewey (author), Animal Diversity Web, University of Michigan Museum of Zoology.
