Raptor biologist and citizen science coordinator Allen Fish has directed the Golden Gate Raptor Observatory since 1985. GGRO is a long term program of the Golden Gate National Parks Conservancy. Allen was a lecturer at UC Davis teaching Raptor Biology through the 2000s, and in 2003 received the Maurice Broun Award for contributions to raptor conservation biology.
In recent decades Cooper’s Hawks have successfully colonized urban landscapes, where there may be... more In recent decades Cooper’s Hawks have successfully colonized urban landscapes, where there may be ample prey but also a greater prevalence of disease in their prey. We searched for nesting Cooper’s Hawks in and around Berkeley, California, from 2002 to 2010, locating 95 nests, 89 of which successfully fledged at least one nestling. On average, each nest produced 3.6 fledglings. We evaluated the possible effects of the protozoan parasite Trichomonas gallinae on Cooper’s Hawk reproduction from the proportion of potential prey items brought to Lindsay Wildlife Experience that tested positive for the parasitic disease. We did not find a correlation between T. gallinae in potential prey species and nest success (i.e., if the nest fledged any offspring) or reproductive success (i.e., number of fledglings produced). Similarly, we did not find a relationship between reproductive success and distance to parks or percent of impervious surface within 500 m of the nest. The high reported rates ...
In recent decades Cooper's Hawks have successfully colonized urban landscapes, where there may be... more In recent decades Cooper's Hawks have successfully colonized urban landscapes, where there may be ample prey but also a greater prevalence of disease in their prey. We searched for nesting Cooper's Hawks in and around Berkeley, California, from 2002 to 2010, locating 95 nests, 89 of which successfully fledged at least one nestling. On average, each nest produced 3.6 fledglings. We evaluated the possible effects of the protozoan parasite Trichomonas gallinae on Cooper's Hawk reproduction from the proportion of potential prey items brought to Lindsay Wildlife Experience that tested positive for the parasitic disease. We did not find a correlation between T. gallinae in potential prey species and nest success (i.e., if the nest fledged any offspring) or reproductive success (i.e., number of fledglings produced). Similarly, we did not find a relationship between reproductive success and distance to parks or percent of impervious surface within 500 m of the nest. The high reported rates of reproduction and high densities of Cooper's Hawk in Berkeley and neighboring Albany suggest a robust population, and we did not find evidence that T. gallinae influences its reproductive success.
Sharp-shinned (Accipiter striatus), C ooper’s (A. cooperil],a nd Red-tailed (Buteo
jamaicensis) h... more Sharp-shinned (Accipiter striatus), C ooper’s (A. cooperil],a nd Red-tailed (Buteo jamaicensis) hawks, and the total species (19) occurring in the Marin Headlands, Marin County, California, were quantified in relation to seven weather variables. Peak counts of raptors occurred in mid- to late September, with counts largely composed of immature hawks. More adult hawks were counted in mid- to late October. Adult and immature Sharpshinned and Cooper’s hawk counts were correlated with days before and after cold fronts, increasing temperature, barometric pressure, wind speed, and decreasing fog cover. Numbers of adult and immature Red-tailed Hawks were correlated negatively with fog and days before cold fronts and positively with temperature and barometric pressure. Cold front presence or absence did not affect Red-tailed Hawk numbers in 1986-1988. Fewer accipiters and Red-tailed Hawks were counted with south winds (headwinds) blowing, and in 1988 more adult birds were counted with north winds (tailwinds). Increasing temperatures, decreasing fog, and an absence of headwinds were correlated the most with counts of all species in the Headlands; cold front presence or absence had no significant influence on numbers in 1986- 1988. A decreasing number of days before and after cold fronts was also generally associated with counts.
Historical records from the early 1900s, as well as surveys updated
in the late 1980s and more re... more Historical records from the early 1900s, as well as surveys updated in the late 1980s and more recent information from local breeding bird atlases, indicate that Ospreys rarely nested on San Francisco Bay prior to 2005. In 2013, we surveyed nesting Ospreys baywide and located 26 nesting pairs, 17 of which were successful and fledged 44 young. We also report on findings from previous annual nest surveys of a portion of San Francisco Bay beginning in 1999. These results demonstrate a greater breeding abundance than has previously been recognized. The density of Osprey nests is highest near the north end of San Francisco Bay, but nesting also appears to be expanding southward. Nearly all of the nests observed were built on artificial structures, some of which were inappropriate and required nests to be removed. Over half of unsuccessful pairs experienced significant human disturbance. We recommend that conservation efforts focus on reducing this ratio, and to help do so, we urge erecting nest platforms as efforts to deter nesting when it conflicts human activity.
... Migración Diferenciada entre Poblaciones Discretas de Juveniles de Buteo jamaicensis.Joshua M... more ... Migración Diferenciada entre Poblaciones Discretas de Juveniles de Buteo jamaicensis.Joshua M. Hull, 1, 2, 4 Holly B. Ernest, 1, 3 Jill A. Harley, 2 Allen M. Fish 2 and Angus C. Hull 2. ... 2008, Goodrich and Smith 2008, A. Hull unpubl. data). ...
In recent decades Cooper’s Hawks have successfully colonized urban landscapes, where there may be... more In recent decades Cooper’s Hawks have successfully colonized urban landscapes, where there may be ample prey but also a greater prevalence of disease in their prey. We searched for nesting Cooper’s Hawks in and around Berkeley, California, from 2002 to 2010, locating 95 nests, 89 of which successfully fledged at least one nestling. On average, each nest produced 3.6 fledglings. We evaluated the possible effects of the protozoan parasite Trichomonas gallinae on Cooper’s Hawk reproduction from the proportion of potential prey items brought to Lindsay Wildlife Experience that tested positive for the parasitic disease. We did not find a correlation between T. gallinae in potential prey species and nest success (i.e., if the nest fledged any offspring) or reproductive success (i.e., number of fledglings produced). Similarly, we did not find a relationship between reproductive success and distance to parks or percent of impervious surface within 500 m of the nest. The high reported rates ...
In recent decades Cooper's Hawks have successfully colonized urban landscapes, where there may be... more In recent decades Cooper's Hawks have successfully colonized urban landscapes, where there may be ample prey but also a greater prevalence of disease in their prey. We searched for nesting Cooper's Hawks in and around Berkeley, California, from 2002 to 2010, locating 95 nests, 89 of which successfully fledged at least one nestling. On average, each nest produced 3.6 fledglings. We evaluated the possible effects of the protozoan parasite Trichomonas gallinae on Cooper's Hawk reproduction from the proportion of potential prey items brought to Lindsay Wildlife Experience that tested positive for the parasitic disease. We did not find a correlation between T. gallinae in potential prey species and nest success (i.e., if the nest fledged any offspring) or reproductive success (i.e., number of fledglings produced). Similarly, we did not find a relationship between reproductive success and distance to parks or percent of impervious surface within 500 m of the nest. The high reported rates of reproduction and high densities of Cooper's Hawk in Berkeley and neighboring Albany suggest a robust population, and we did not find evidence that T. gallinae influences its reproductive success.
Sharp-shinned (Accipiter striatus), C ooper’s (A. cooperil],a nd Red-tailed (Buteo
jamaicensis) h... more Sharp-shinned (Accipiter striatus), C ooper’s (A. cooperil],a nd Red-tailed (Buteo jamaicensis) hawks, and the total species (19) occurring in the Marin Headlands, Marin County, California, were quantified in relation to seven weather variables. Peak counts of raptors occurred in mid- to late September, with counts largely composed of immature hawks. More adult hawks were counted in mid- to late October. Adult and immature Sharpshinned and Cooper’s hawk counts were correlated with days before and after cold fronts, increasing temperature, barometric pressure, wind speed, and decreasing fog cover. Numbers of adult and immature Red-tailed Hawks were correlated negatively with fog and days before cold fronts and positively with temperature and barometric pressure. Cold front presence or absence did not affect Red-tailed Hawk numbers in 1986-1988. Fewer accipiters and Red-tailed Hawks were counted with south winds (headwinds) blowing, and in 1988 more adult birds were counted with north winds (tailwinds). Increasing temperatures, decreasing fog, and an absence of headwinds were correlated the most with counts of all species in the Headlands; cold front presence or absence had no significant influence on numbers in 1986- 1988. A decreasing number of days before and after cold fronts was also generally associated with counts.
Historical records from the early 1900s, as well as surveys updated
in the late 1980s and more re... more Historical records from the early 1900s, as well as surveys updated in the late 1980s and more recent information from local breeding bird atlases, indicate that Ospreys rarely nested on San Francisco Bay prior to 2005. In 2013, we surveyed nesting Ospreys baywide and located 26 nesting pairs, 17 of which were successful and fledged 44 young. We also report on findings from previous annual nest surveys of a portion of San Francisco Bay beginning in 1999. These results demonstrate a greater breeding abundance than has previously been recognized. The density of Osprey nests is highest near the north end of San Francisco Bay, but nesting also appears to be expanding southward. Nearly all of the nests observed were built on artificial structures, some of which were inappropriate and required nests to be removed. Over half of unsuccessful pairs experienced significant human disturbance. We recommend that conservation efforts focus on reducing this ratio, and to help do so, we urge erecting nest platforms as efforts to deter nesting when it conflicts human activity.
... Migración Diferenciada entre Poblaciones Discretas de Juveniles de Buteo jamaicensis.Joshua M... more ... Migración Diferenciada entre Poblaciones Discretas de Juveniles de Buteo jamaicensis.Joshua M. Hull, 1, 2, 4 Holly B. Ernest, 1, 3 Jill A. Harley, 2 Allen M. Fish 2 and Angus C. Hull 2. ... 2008, Goodrich and Smith 2008, A. Hull unpubl. data). ...
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Papers by Allen M Fish
jamaicensis) hawks, and the total species (19) occurring in the Marin Headlands, Marin
County, California, were quantified in relation to seven weather variables. Peak counts of
raptors occurred in mid- to late September, with counts largely composed of immature
hawks. More adult hawks were counted in mid- to late October. Adult and immature Sharpshinned
and Cooper’s hawk counts were correlated with days before and after cold fronts,
increasing temperature, barometric pressure, wind speed, and decreasing fog cover. Numbers
of adult and immature Red-tailed Hawks were correlated negatively with fog and days before
cold fronts and positively with temperature and barometric pressure. Cold front presence
or absence did not affect Red-tailed Hawk numbers in 1986-1988. Fewer accipiters and
Red-tailed Hawks were counted with south winds (headwinds) blowing, and in 1988 more
adult birds were counted with north winds (tailwinds). Increasing temperatures, decreasing
fog, and an absence of headwinds were correlated the most with counts of all species in the
Headlands; cold front presence or absence had no significant influence on numbers in 1986-
1988. A decreasing number of days before and after cold fronts was also generally associated
with counts.
in the late 1980s and more recent information from local breeding bird atlases, indicate
that Ospreys rarely nested on San Francisco Bay prior to 2005. In 2013, we
surveyed nesting Ospreys baywide and located 26 nesting pairs, 17 of which were
successful and fledged 44 young. We also report on findings from previous annual
nest surveys of a portion of San Francisco Bay beginning in 1999. These results
demonstrate a greater breeding abundance than has previously been recognized.
The density of Osprey nests is highest near the north end of San Francisco Bay, but
nesting also appears to be expanding southward. Nearly all of the nests observed
were built on artificial structures, some of which were inappropriate and required
nests to be removed. Over half of unsuccessful pairs experienced significant human
disturbance. We recommend that conservation efforts focus on reducing this ratio,
and to help do so, we urge erecting nest platforms as efforts to deter nesting when
it conflicts human activity.
jamaicensis) hawks, and the total species (19) occurring in the Marin Headlands, Marin
County, California, were quantified in relation to seven weather variables. Peak counts of
raptors occurred in mid- to late September, with counts largely composed of immature
hawks. More adult hawks were counted in mid- to late October. Adult and immature Sharpshinned
and Cooper’s hawk counts were correlated with days before and after cold fronts,
increasing temperature, barometric pressure, wind speed, and decreasing fog cover. Numbers
of adult and immature Red-tailed Hawks were correlated negatively with fog and days before
cold fronts and positively with temperature and barometric pressure. Cold front presence
or absence did not affect Red-tailed Hawk numbers in 1986-1988. Fewer accipiters and
Red-tailed Hawks were counted with south winds (headwinds) blowing, and in 1988 more
adult birds were counted with north winds (tailwinds). Increasing temperatures, decreasing
fog, and an absence of headwinds were correlated the most with counts of all species in the
Headlands; cold front presence or absence had no significant influence on numbers in 1986-
1988. A decreasing number of days before and after cold fronts was also generally associated
with counts.
in the late 1980s and more recent information from local breeding bird atlases, indicate
that Ospreys rarely nested on San Francisco Bay prior to 2005. In 2013, we
surveyed nesting Ospreys baywide and located 26 nesting pairs, 17 of which were
successful and fledged 44 young. We also report on findings from previous annual
nest surveys of a portion of San Francisco Bay beginning in 1999. These results
demonstrate a greater breeding abundance than has previously been recognized.
The density of Osprey nests is highest near the north end of San Francisco Bay, but
nesting also appears to be expanding southward. Nearly all of the nests observed
were built on artificial structures, some of which were inappropriate and required
nests to be removed. Over half of unsuccessful pairs experienced significant human
disturbance. We recommend that conservation efforts focus on reducing this ratio,
and to help do so, we urge erecting nest platforms as efforts to deter nesting when
it conflicts human activity.