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Henslow’s sparrow (Ammodramus henslowii)
Henslow‟s sparrows, a SGCN, were recorded in 2009 and were observed for four of the
past five years at AHATS during INRMP surveys. None were observed during 2008. However,
this could be due to the timing of 2008 surveys which were later than the previous five years, or
could indicate that 2006 was the peak of a local eruption of the species (Figure 67). Henslow‟s
sparrow sightings increased in the Minnesota region during the summer of 2005, the year they
were first observed at AHATS. Possible causes for increased sightings may be due to a temporary
population increase, a temporary population shift from another area, or a true population increase.
Annual monitoring will provide information regarding their continued presence on AHATS
(Dirks et al. 2009).
Henslow‟s sparrows are listed as endangered by the MNDNR and six other states, but are
not listed by the U.S. Fish and Wildlife Service. This species usually breeds in the grasslands to
the south and east of Minnesota. The nationwide population of this grassland bird species has
declined nearly 80 percent since 1966, due to habitat destruction and/or reforestation (National
Audubon Society 2007). Management for this species should provide for large areas of suitable
habitat, prevention of disturbance during the breeding season, and the control of succession
(Herkert et al. 2003). Suitable habitat is usually tall, dense grass with a deep litter layer and
scattered tall forbs for perching. Periodic disturbance, such as prescribed fire, may be essential to
maintaining suitable habitat; even though it will likely reduce the suitability of the grassland
during the treatment year. Trees and shrubs should be eliminated in the center and along the
edges of grassland areas to discourage predators and nest parasites such as the brown-headed
cowbird. The grassland areas where Henslow‟s sparrows were located should not all be burned in
the same year, allowing some habitat to remain each year. These grasslands should be burned on
a four or five year rotation, since it may take several years for the habitat to regain suitable
structure for nesting Henslow‟s sparrows (Dirks et al. 2009). Habitat requirements and
management for Henslow‟s sparrows will be included in the development of future habitat
restoration plans.
Osprey (Pandion haleaetus)
During the 2009 nesting season, an osprey (Pandion haleaetus) pair was observed on the
nesting platform at Marsden Lake. In July, two female osprey chicks were banded and one
unhatched egg was also found. The osprey chick banding was conducted in cooperation with the
University of Minnesota Raptor Center and Excel Energy, who provided the bucket truck for
access to the platform.
Bird Nest Boxes
Nest boxes have been installed at AHATS in previous years by the Audubon Society and
other local groups. These nest boxes are monitored and maintained by Craig Andreson, a
volunteer with the St. Paul Audubon Society. In 2009, 388 bluebird nest boxes fledged
approximately 415 eastern bluebirds, 250 tree swallows, and over 200 house wrens. In addition,
2009 Conservation Program Report
Page 100