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Threats | |
| Description Status Range & Distribution Reproduction Habitat Threats Literature Cited Author: Neil Crouch |
Shrike populations are declining at a rate of 3.7% a
year (Grisham 1994). Field studies generally implicate alterations in habitat structure
and loss of habitat as factors responsible for changes in breeding distribution and
overall abundance (Cade and Woods 1996). One such habitat alteration includes the
increased density of shrubs. In one study, loggerhead shrikes did not respond directly to
mesquite density, the abundance of loggerhead shrikes was positively correlated with an
increasingly patchy distribution of mesquite (Lloyd et al. 1998). This was due to the fact
that loggerhead shrikes rely upon elevated perches in open areas from which to hunt their
prey, and thus would benefit from a mix of open grassland and scattered mesquite (Porter
et al. 1975). Hence, it is recommended that extensive preservation of the natural scrub
desert, shrub-steppe, western oak savanna, and southern savanna vegetation types, which
appear to be optimal, core habitats for this species, as well as fostering land-use
practices that favor shrikes in agricultural and suburban landscapes be implemented in
order to preserve this species (Cade and Woods). Another hypothesis explaining the decline of the loggerhead shrike focuses on the fire ant. Scientists have looked at changes in the shrike’s winter habitat and found that, in addition to changes in land use, the shrike’s decline in particular counties directly correlated with an increase in fire ants in the same areas. Further investigation revealed that the shrike and fire ant are direct competitors for food sources. Both feed on invertebrates, reptiles, and small mammals (Grisham 1994). Thus, fire ant control could benefit the loggerhead shrike. |