A History of Ospreys on Martha's Vineyard (a work in progress)
Contents:
Introduction
- An overview of the population and
our management efforts
Nest Poles
- A chronicle of the rise of the
Vineyard population as nest poles were provided. A Decade of Osprey Data
- A summary of 10 years' data on the
reproductive success of the Island's Ospreys.
Yearly
Summaries - More
detailed reviews of each year's census.
Introduction
Gus Ben David, recently retired
director of Mass Audubon's Felix Neck Wildlife Sanctuary and
godfather to the 60-70 pairs of Ospreys now breeding on Martha's Vineyard, kept
track of the Ospreys on the Vineyard from 1970 through 1992. During this time
the Osprey population grew from 2 pairs to over 70 thanks to the efforts of Gus
and his dedicated crew. Gus couldn't keep up with the censuses
during the mid 90s, a period which saw a decline in the number of chicks the
Vineyard Ospreys were able to raise.
In 1998, I decided to pick up the censuses again. That year I
visited all 114 nest poles on the Island (taking an interesting trip down Memory
Lane in the process) and enlisted
the help of land owners and Osprey aficionados to track the fledging rates across the
island. The 1998 data were encouraging. For the 50 nests for which we had data, there were
33 successful nests producing 54 young, well over the rate of 0.8 young/active nest
that has been calculated as
the minimum required to sustain a population.
Eleven years later, in 2008, 70
pairs of Ospreys fledged a remarkable 121 young--probably the most ever raised
on Martha's Vineyard. In 2010, we saw the
beginnings of the baby-boom resulting from those 121 young, just starting to
return to their natal areas. The number of nesting pairs was a record 74 and 12
additional pairs were either house-keeping or house-hunting. (We define
housekeepers as pairs that build a pretty much complete nest but don't lay eggs,
while house-hunters are young birds that are just thinking about it and put a
bunch of sticks on a possible nest site but whose construction efforts never
really result in what we'd call a nest.)
Population Growth
While no accurate records exist, there were probably never more than
five to ten pairs in the 1900s through the early 60s. Most nests that are
remembered were in old pines left from extensive fires in the 1930s and 1940s. One
pair nested in a beetlebung tree at Priester's or Crocker's Pond along North Rd.
This is a spot that is still popular among the Vineyard Ospreys, although there
hasn't been a nest there since sometime in the 60s.
When our studies began in 1971, there were two
pairs--one on a pole erected in the winter of 69-70 to replace a fallen nest
tree along Deep Bottom and one in a dead pine at Mink Meadows. After that first
pole in 1970, more artificial nest platforms were provided, originally for the traditional pairs whose nests
in dead pine trees were lost in winter storms and later as new pairs were discovered
attempting to build nests on power transformers. (Veteran line crews remember knocking
Osprey nests off of power poles as far back as the 1950s.)
Since 1971, 127 nest poles have been erected, and the Vineyard Osprey
population increased to a peak of more than 70 pairs in 1992. Details of the
remarkable efforts of Gus Ben David and the Felix Neck Osprey crew are presented
below.
The population increased exponentially from 1975 through 1990, more
than doubling every five years. Productivity during this time averaged 1.84 young fledged
per breeding pair.
Beginning in 1992, Gus noticed a dramatic decline in the number of young
fledged on the Island.
Observations of Osprey's hunting and breeding behavior indicated a widespread collapse of the Ospreys' prey base.
In 1998 I restarted the annual census program. From 1998
through 2007 the population fluctuated between 58 and 67 breeding pairs, with
good reproductive success.
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In the early 70s, we were scratching our heads wondering why the Vineyard
Ospreys were fledging ("fledging" occurs when a young bird leaves the
nest) a remarkable 3 or 4 young per nest, but we weren't seeing an increase in
the number of breeding pairs.
The number of young fledged was remarkable for two
reasons. First, Ospreys very rarely lay 4 eggs, and it is even more unusual for
all 4 young to fledge. Secondly, the Ospreys in southern New England were still
suffering from the vast quantities of DDT that we had sprayed across their
habitat since DDT was invented in the late 40s. DDT caused Ospreys (and Bald
Eagles, Peregrine Falcons, and Brown Pelicans) to lay very thin-shelled eggs.
This, in turn, led to very poor reproduction and rapidly declining populations.
The number of Osprey pairs nesting from Boston to New York City crashed from
about 1000-1200 in the pre-DDT era (the 40s and before) to just over 100 in the
early 1970s.
While most of the southern New England Ospreys were having difficulty fledging
any young, the Mink Meadows pair fledged 11 in three years!
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A conversation between
Gus Ben David and one of the local power company's line crew provided the
explanation. It turned out that for some years the line crews had been removing
Osprey nests from power transformers. An Osprey nest on a power
transformer is a very dangerous thing. While in general wood is not a
conductor of electricity, a stick that was soaking in salt water before
becoming part of an Osprey nest can short out and destroy a very expensive
transformer (not to mention killing an Osprey on that nest) when moistened
by a heavy fog. All of this was going on primarily along the sparsely
populated (by humans) south shore, where power poles extend above the salt
spray-stunted forest canopy, making them very attractive spots for an
Osprey nest, given the Osprey's penchant for building a nest on the
tallest thing around. Once we learned that there was indeed a population of Ospreys trying build nests, Gus mobilized a coalition of the Osprey willing--the local power company, land owners, and a crew of dedicated souls willing and eager to put a pole up by hand, if need be. |
|
For the first few years, the Osprey crew operated
in reactive mode--waiting for a pair of Ospreys to start building a nest
on a power pole. Once alerted of a problem pair, the crew quickly put up a safe alternative and knocked the
nest off the hot pole line. Making sure the new pole was a bit higher than
the site where the pair had been building was all it took to get the birds
to switch--Ospreys are suckers for a view. With time, Gus was able to get supply ahead of demand and begin putting up "speculation poles" --anticipating where Ospreys would want to nest. Many of these were used, but to this day, with more than 40 poles unoccupied, there are still pairs that decide they prefer a chimney, TV antenna, or power pole, and Gus is busy every spring dealing with problem birds. Through the 70s and mid 80s, the Osprey population on the Vineyard more than doubled every five years. This was as clear an indication as could be that the population was limited by nest sites. The chart below depicts the growth of the Osprey population on Martha's Vineyard, showing the rapid increase during the 70s and 80s with a leveling off through the 90s and beginning of the "naughts" (the 2000s). This plateau in the population size is most intriguing. While it is obvious that the population was limited by available nest sites before 1990, it is not clear what's keeping the population from increasing above about 60-65 breeding pairs. Food is the obvious first guess, but this doesn't make sense, given the high numbers of young that have been fledged over the past 10 years. Nest sites can't be the limiting factor, as there are about 40 poles that are available. Some of these have never been used, so they may not really be "available," as far as Ospreys are concerned, but there are a number of poles that have a long history of use that now stand empty. Territoriality might be an explanation. In many animal species, territorial behavior keeps populations below levels that would exceed the carrying capacity of the local environment. Although Ospreys can be quite tolerant of nesting in close proximity, some pairs will aggressively defend potential sites near their nests. Some of the unused and formerly occupied poles are close to active pairs, so that might explain in part why we don't see more pairs nesting in those areas, but some unused nests are remote, not near any potentially territorial pairs, and had long histories of active and productive pairs nesting on them. In my mind, this is one of the great unsolved mystery of the Vineyard Ospreys. (The other is why the Vineyard population recovered from DDT so much sooner than other New England colonies.) |
 |
This graph charts the
increase in the Vineyard population in response to an increased
availability of nest sites. "Poles" are mostly poles erected
specifically for Osprey nests, but a few are old abandoned power lines.
The pink line represents data collected by Gus Ben David from 1969 through
1992. No data were collected from 1993-1997, so I estimated the number of
pairs during that time. "Pairs II" show the data I and a number
of students and volunteers have collected during the past 10 years. Something other than nest site availability appears to be limiting the Island population. |
In 2007 there were 135 sites that at one time
or another in the past 10 years had saw some Osprey activity. 119 were poles set
up for Ospreys, five were on old or active power lines, five were on houses or
sheds (mostly chimneys), four were in trees, one on a boat, and one on a high
school athletic field light tower. Of these, 72 were used in ’07.
2007 Nest Structures
| Structure | Number |
| Power line | 5 |
| Pole | 61 |
| Chimney | 2 |
| Tree | 2 |
| Raft/boat | 1 |
| Light tower | 1 |
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A Decade of Osprey Population Data
Since I began the current census, the number of nesting pairs (defined here as birds with eggs and pairs that make a serious effort at building a nest but don't lay eggs) has remained quite stable. Each year we have a few pairs for which we're not sure what category applies. Because the nests are scattered over the whole Island, often in remote areas, and because the beginning of nesting across the Vineyard is spread out over at least a three week period, we can't always get to every nest as early as we would like. Some years the first inventory of all possible poles and known nesting sites was made fairly late, so we might have missed some early nesters whose nests failed due to bad spring weather. Some of these birds might appear in our data as "housekeepers".
10-year totals for young fledged
Over the past decade, 96 poles or nest sites have had at least one year
with breeding birds. From those nests 675 young have been fledged.
As
we commonly find in animal populations, a few pairs are often responsible for
much of the successful breeding. Thirty-three nest sites have been active all 10
years and those sites fledged 424 young. Thirteen of those 33 nests produced a
bit more than half of these 424 young.
While some pairs or at least poles (it is
likely that most of the poles that have been occupied for 10 years have had some
mate replacement) are “overachievers”, there is a corresponding group of
underachievers. Of poles or nest sites that have at least 5 years of activity,
19 averaged less than one fledgling per year. Birds clearly get better at
raising young, which explains part of this phenomenon.
These have been the most productive Osprey pairs on Martha's Vineyard from 1998
through 2007:
| NEST Stonewall Pond/Couch Cottage Lobsterville/Batzer Farm Neck Mink Meadows/Lukes O.B. Harbor Pole Wasque/Trustees of Reservations Dyke Bridge Long Point/Middle Pt. Cove Cedar Tree Neck North Shore/Dr. Ganz |
TOTAL FLEDGED 21 20 17 17 17 16 16 16 16 16 |
Average number of young fledged.
The two graphs below track the average number of young fledged per active nest
(the first graph) and per successful nest (the second). Data from Martha's
Vineyard are plotted in blue, while data from the Westport River colony are in
pink. (Thanks to Alan Poole and his colleagues there for permission to post this
data.) Looking at the average number of young fledged per nest that had eggs
(active nests), it is interesting to note the degree to which the two colonies
are not in synch, despite their proximity--it's about 15 miles from the Vineyard
to the Westport River.
In contrast, there is little difference, both from year
to year within the colonies and when comparing the two colonies to each other.
This suggests that weather during incubation plays a large role in determining
the reproductive success of a colony.
 |
|
 |
The Year-by-Year Details
Detailed Yearly Summaries
1998,
1999,
2000,
2001, 2002,
2003, 2004
2005,
2006,
2007
When the data from the last few nests came in for 1998,
we discovered that the success of the Vineyard birds was even higher than I
reported earlier in the year.
Of the 66 active nests in 1998, we know the outcome of 56. Those 56 nests
fledged roughly 64 young, for an average of 1.14 fledglings/active nest. This is
well over the break-even rate of rate 0.8 young per nest needed for an Osprey
population to remain stable.
| Nests with eggs | 66 |
| Housekeepers/hunters | 4 |
| Uncertain status | |
| Pairs at nests | 70 |
| Nests reported | 56 |
| Successful nests | 38 |
| % active nests successful | 67.9% |
| Failures | 18 |
| No data | 10 |
| Fledglings | 64 |
| Fledglings/known-outcome nest | 1.14 |
| Fledglings/successful nest | 1.68 |
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1999 was another productive year for the Vineyard
Ospreys. My spring trip revealed 63 active nests, with six pairs of
"housekeepers." Housekeepers are usually young birds that are
beginning to establish a territory. The number of nesting pairs was down from 66
in 1998, but I didn't count until a bit later in the spring of '99, so I might
have missed a couple of pairs that failed and abandoned their nests early.
Nonetheless, the six pairs of housekeepers and the continued reproductive
success augur well for the Vineyard Osprey colony.
This
being only the second year of our fledgling effort to census all the Island's
Ospreys, we wound up missing data from 10 nests. There were still a few kinks to
be worked out. For the nests we do know about, the number of fledglings per
active nest for 1999 was 1.21, almost the same as last year.
| Nests with eggs | 63 |
| Housekeepers/hunters | 6 |
| Uncertain status | |
| Pairs at nests | 69 |
| Nests reported | 53 |
| Successful nests | 41 |
| % active nests successful | 77.4% |
| Failures | 12 |
| No data | 10 |
| Fledglings | 64 |
| Fledglings/known-outcome nest | 1.21 |
| Fledglings/successful nest | 1.56 |
Changes:
Four
pairs downgraded from active to housekeeping (Scrubby Neck/Gerry De Blois,
Chappy/Katama Bay-Getsinger, Potter/Boathouse, Trapp Pond/Gatting), while one
pair went from active to inactive (Deep Bottom/Everett Jones), and four from
housekeepers to inactive (State Forest/Engley's, Seven Gates/Ames, Katama
Point/Land Bank #1, Middle Pt. Cove south/Egan).
One
new pair showed up at a formerly inactive pole on Swan Neck (Kohlberg). This
nest has been active ever since. Two new housekeepers showed up (Katama
Bay/Stevens, Trapps Pond/Lil Province), and Julie Ben David found a pair nesting
in a tree in Jane’s Cove off of Edgarttown Great Pond.
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2000 was a very good year. "Pairs at
nests" includes active breeders (those with eggs) and housekeepers--mostly
young birds getting started in the breeding business, but not closing the deal
with eggs. In this department, the population has been steady at around 70 for
the first three years of this study.
A remarkable 96 young were fledged--and
this is a conservative estimate (some nests were checked
after the young had already been on the wing and some could have missed). This
translates to 1.57 fledged per active nest, up significantly from last
year's 1.19. Nine nests fledged three young and the pair at Wasque succeeded in
raising four!
| Nests with eggs | 63 |
| Housekeepers/hunters | 6 |
| Uncertain status | 1 |
| Pairs at nests | 70 |
| Nests reported | 61 |
| Successful nests | 53 |
| % active nests successful | 86.9% |
| Failures | 8 |
| No data | 2 |
| Fledglings | 96 |
| Fledglings/known-outcome nest | 1.57 |
| Fledglings/successful nest | 1.81 |
Changes
Three new sites were occupied by housekeepers in 2000 (Mink Meadows
Chimney/Goff, Wintucker/Dyke (old powerline), Mink Meadows GC/Pitch Pine).
Two
active pairs from last year did not return (Scrubby Neck 3/nr Watcha, Chappy/Dr.
Self), and five pairs upgraded from housekeeping to active (Katama Bay/Stevens,
Scrubby Neck/Gerry De Blois, Chappy/Katama Bay-Getsinger, Potter/Boathouse,
Trapp Pond/Gatting).
Two
pairs used poles that were inactive last year (Little Neck/Silva & Brown,
Deep Bottom/Everett Jones).
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The
2001 breeding season was less successful than any since we started careful
monitoring in 1998. While we found 63 active nests (nests with eggs) during our
May inventory–exactly the same number of breeding pairs as in ’99 and
‘00–the number of young produced was down.
Severe weather in June is probably responsible for many of the 21 nest
failures we witnessed in ’01. Despite all these nests that produced no young,
we estimate that 1.03 young were fledged for each nest where eggs were laid.
While this is the lowest productivity from the Vineyard Ospreys since 1998, it
is still above the “break-even” value of 0.8 that Osprey researchers
believe is necessary to keep a population stable.
Four pairs were “house-keeping” – a not-so-technical term that
describes the behavior of young birds that are getting ready to breed but
don’t quite have it all together yet. These housekeepers usually breed after a
year or two of practice.
Fledging
Success in 2001
As previously mentioned, 2001 was a relatively poor year for Osprey productivity on the Vineyard. Ospreys are long-lived, however, often breeding well into their teens, so one, or even a series of off years is no reason for concern. An adult Osprey might attempt to raise young in as many as 10 breeding seasons and only has to successfully rear one young that will survive to breeding age (3-4 years) in those 10 years to keep the population stable.
| Nests with eggs | 63 |
| Housekeepers/hunters | 4 |
| Uncertain status | 0 |
| Pairs at nests | 67 |
| Nests reported | 62 |
| Successful nests | 41 |
| % active nests successful | 66.1% |
| Failures | 21 |
| No data | 1 |
| Fledglings | 64 |
| Fledglings/known-outcome nest | 1.03 |
| Fledglings/successful nest | 1.56 |
Changes
Several “old faithful” nests were unoccupied in ’01, including nest
#8 out on Squibnocket, which had been continuously active for nearly 20 years.
One of the Oyster Pond nests “downgraded” from breeding to housekeeping,
suggesting that at least one of the old pair from this long-active nest had not
survived the winter and was replaced by a young bird. A pair at Scrubby Neck
also dissappeared. After this nest pole was blown to smithereens by a lightning
bolt in ’00 (with eggs or young in the nest), the pair set up a nest on a
power line near the old nest pole
in ’01. Their nest failed that year, and in ’02 they were not among those
present and accounted for. Two neighboring pairs to the west also disappeared in
’01. Nearby, a pair of ’00 housekeepers at the end of Oyster-Watcha Rd. laid
eggs in ’01 but did not raise any young.
On Chappy, the unofficial Opsrey capitol of the Vineyard, a pole out at
Shearpin Pond (at the north end of the island) had housekeepers as did a pole
across the water on the west shore of Poucha. On the Katama Bay side, a pair of
‘00 housekeepers just north of Wasque on Katama Bay laid eggs (but failed),
and late in the season a pair showed up north of Litchfield Rd and started
building a nest on a power line on perhaps the highest ground on Chappy. Another
(or maybe the same) pair put some sticks on the short pole on the northeast
corner of Caleb’s Pond.
Along the north shore, a pair built a nest and laid eggs on a chimney at
Mink Meadows. At Paul’s Point, where we had a housekeeping pair on the
Guiney's property in ’00, a pair built a nest on a powerline not far from the
housekeeping nest of the year before—these were probably the same birds.
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In mid May we completed our annual grand tour of all the known nesting
sites on the Island for a head count of this year’s breeders. And a “head
count” it really is. By the middle of May, all the birds that will lay eggs
will have done so, and the females are busy incubating. When they are
incubating, often all that’s visible from the ground is the female's mostly
white head. This is very conspicuous, so just a glance up at the nest is usually
all that is needed to confirm that a pair is breeding.
We found 58 pairs incubating eggs—four pairs fewer than last year—and
five housekeepers. As last year, a few “old faithful” nests went unoccupied.
While the number of pairs was down a bit, productivity rebounded to 1.33, up from the relatively poor year in 2001.
| Nests with eggs | 58 |
| Housekeepers/hunters | 5 |
| Uncertain status | 1 |
| Pairs at nests | 64 |
| Nests reported | 58 |
| Successful nests | 49 |
| % active nests successful | 84.5% |
| Failures | 9 |
| No data | 0 |
| Fledglings | 77 |
| Fledglings/known-outcome nest | 1.33 |
| Fledglings/successful nest | 1.57 |
Changes
The pole overlooking the Menemsha Pond herring run at Squibnocket has
"downgraded" from active to housekeepers and is apparently having
trouble getting a nest started. On Menemsha Pond a pair is housekeeping on James
Taylor's pole (finally). Whit Manter's nest on Tisbury Great Pond is empty after
a long run. A pair has resumed residence at the summer parking area at Long
Point. A pair on the Jones farm that has tried off and on for the past few years
has apparently given up. At Sippiessa Pt/Clam Cove, the nest near the boat
landing is unoccupied after several years of failures. The south shore nest
occupied by HX and KD, the satellite tagged birds we followed on migration last
fall, is inactive. A neighboring nest on Oyster Pond is active again after a
year off. Other nests inactive this year include Mohu, the pair at the end of
Oyster-Watcha Rd., and Little Neck (Shearpin Pond on Chappy).
A housekeeping pair has taken up residence on a pole at Eel Pond in
Edgartown, while over on Chappy, a pair is back at the Self's nest on Cape Pogue
Bay. The 2001 housekeepers on the power line on Litchfield Rd are incubating.
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Was a very good one. The eight housekeeping pairs suggests that we're seeing the results of the good years around the turn of the century. The similarity in the number of young fledged/active nest and the number of young fledged/successful nest reflects the very low number of nest failures, and this is usually the result of benign weather during incubation.
| Nests with eggs | 60 |
| Housekeepers/hunters | 8 |
| Uncertain status | 2 |
| Pairs at nests | 70 |
| Nests reported | 58 |
| Successful nests | 52 |
| % active nests successful | 89.7% |
| Failures | 6 |
| No data | 0 |
| Fledglings | 81 |
| Fledglings/known-outcome nest | 1.40 |
| Fledglings/successful nest | 1.56 |
Changes
Among
the active pairs in ’02, three moved from active to housekeepers (Tisbury G
Pond/Soo & Flip, Squibnocket/Howland, Jane's Cove Tree nest), two from
active to uncertain (Harlock Pond/Saltonstall, Paul's Pt. Power Line), and two
went inactive (Nashaquitsa/Michael Straight, Watcha Pond/Roger Fisher).
Four
’02 housekeepers graduated to active breeders (Eel Pond/Planting Field Way,
TTOR-gatehouse/Big Homer/Egan, Menemsha Pond/James Taylor, Sepiessa boat
launch), and two did not return (Squibnocket/Fischer, Wasque-Katama
Bay/Belcher).
Four
pairs started breeding on poles that were inactive the year before (Long Cove
South/Egan, Seven Gates/Ames, Hornblower/Walsh, Deep Bottom/Everett Jones).
Four
housekeeping pairs set up shop on poles that had been inactive in ’02 (Katama
Point/Land Bank #1, Gay Head/Outermost Inn, Chilmark Pond/Dwight Salmon,
Lamberts Cove/Guiney).
Two
new pairs showed up on previously unused structures, one in a pine tree (Mink
Meadows Pine/Goff house) and one on a light tower at the high school athletic
field.
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2004 was not a very good
year. We saw just, as Soo Whiting put it, just a feather under 1.00 young fledged
per active nest. The number of breeding pairs was up to 67, but there seems to
have been a shortage of fish. A number of nests went from 3 to 2 to 1 young over
the course of the spring, and we had a fairly large number of nests fail.
| Nests with eggs | 67 |
| Housekeepers/hunters | 5 |
| Uncertain status | 3 |
| Pairs at nests | 75 |
| Nests reported | 62 |
| Successful nests | 41 |
| % active nests successful | 66.1% |
| Failures | 21 |
| No data | 0 |
| Fledglings | 61 |
| Fledglings/known-outcome nest | 0.98 |
| Fledglings/successful nest | 1.49 |
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The 2005 Breeding Season
2005 was another year with low
productivity. This was the first year that over half the active nests (those
that laid eggs) failed. The number of young/active nest was below the break-even
level of 0.8 for the first time since 1998. This was due primarily to really
harsh weather during incubation. The fledging rate for nests that were
successful remained quite high (1.54), suggesting that there was plenty of fish
to go around once, if the eggs survived the early spring storms.
Normally the pairs that lay early are the most
productive. These are usually adults with a lot of experience that have been
paired up for a long time. When they get back from migration they're ready to
get right down to it and lay eggs. Birds that lay later are often younger, less
experienced birds, which rarely do as well as the older birds. This year was an
exception. Many of the older pairs laid early, only to be hit with really bad
weather. Many of the females couldn't keep their eggs warm enough, and there
were lots of early failures. The late nesting birds missed the really bad
weather and fared much better than the old timers.
| Nests with eggs | 61 |
| Housekeepers/hunters | 9 |
| Uncertain status | 5 |
| Pairs at nests | 75 |
| Nests reported | 61 |
| Successful nests | 26 |
| % active nests successful | 42.6% |
| Failures | 35 |
| No data | 0 |
| Fledglings | 40 |
| Fledglings/known-outcome nest | 0.66 |
| Fledglings/successful nest | 1.54 |
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The 2006 Breeding Season
| Nests with eggs | 56 |
| Housekeepers/hunters | 17 |
| Uncertain status | 5 |
| Pairs at nests | 78 |
| Nests reported | 56 |
| Successful nests | 37 |
| % active nests successful | 66.1% |
| Failures | 19 |
| No data | 0 |
| Fledglings | 49 |
| Fledglings/known-outcome nest | 0.88 |
| Fledglings/successful nest | 1.32 |
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The 2007 Breeding Season...
was better than we had expected
midway through. The Vineyard was hit by a wild storm when many birds were on
eggs. The April 18th storm was the first one since 1991 strong enough to cut
through the barrier beach that connected Chappaquiddick to "mainland"
Martha's Vineyard. Fourteen nests failed--not as many as in 2006, and only about
half as many as in 2005.
| Nests with eggs | 62 |
| Housekeepers/hunters | 6 |
| Uncertain status | 2 |
| Pairs at nests | 70 |
| Nests reported | 62 |
| Successful nests | 48 |
| % active nests successful | 77.4% |
| Failures | 14 |
| No data | 0 |
| Fledglings | 84 |
| Fledglings/known-outcome nest | 1.35 |
| Fledglings/successful nest | 1.75 |
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