Common Tern Habitat Improvement Project: 2011 Buffalo Harbor Tern Colony Enhancements and Status Assessment

Niagara Power Project (FERC No. 2216)

January 2012

Prepared by: Riveredge Associates

Prepared for: New York Power Authority

Table of Contents

ACKNOWLEDGMENTS. 1

1.0               INTRODUCTION.. 1-1

2.0               BACKGROUND.. 2-1

2.1         Tern Nesting and Nesting Monitoring.. 2-1

2.2         Recent Tern Management Efforts in Buffalo Harbor.. 2-2

3.0               METHODS. 3-1

3.1         Annual Operation and Maintenance of Enhanced Areas  3-1

3.2         Monitoring of Enhanced Nesting Areas. 3-1

3.3         Data Analysis. 3-2

4.0               RESULTS. 4-1

4.1         Maintenance of Enhanced Areas. 4-1

4.1         Number of Nests. 4-5

4.2         Productivity.. 4-9

5.0               DISCUSSION.. 5-1

6.0               REFERENCES. 6-1

LIST OF FIGURES

Figure 1-1. Location of Common Tern HIP Enhancements in Buffalo Harbor   1-2

Figure 4-1. Early April Conditions at Old Breakwater South.. 4-2

Figure 4-2. Installation of Perimeter Fence and Interior Dividers  4-3

Figure 4-3. Aerial View of Enhanced Areas with Nesting Terns (May 2011) 4-4

Figure 4-4. Late April Storm Damage on the North Breakwater.. 4-6

Figure 4-5. Terns Establishing Territories and Incubating Eggs. 4-7

Figure 4-6. Number of Tern Nests During Annual Index Counts on Buffalo Harbor Breakwaters. 4-8

Figure 5-1. Number of Tern Nests During The Annual Index Count on Buffalo Harbor Breakwaters Over Last Ten Years (2002-2011) 5-2

LIST OF TABLES

Table 1-1.  Locations and Area of Enhancements Completed in 2009 and 2010  1-2

Table 4-1. Number of Tern Nests During Annual Index Count in Buffalo Harbor, 2004-2011. 4-6

Table 4-2. Tern Productivity on Buffalo Harbor Breakwaters 2004-2011  4-11

ACKNOWLEDGMENTS

The New York Power Authority and Riveredge Associates would like to thank the U.S. Army Corps of Engineers for their cooperation in the implementation of the Common Tern Habitat Improvement Project on the breakwaters of Buffalo Harbor.

In addition, the New York Power Authority and Riveredge Associates would like to thank the New York State Department of Environmental Conservation for sharing many years of tern nesting data for Buffalo Harbor.

1.0       INTRODUCTION

The New York Power Authority (NYPA) is pursuing several habitat improvement projects (HIPs) benefiting birds and other wildlife as part of the Niagara Power Project Comprehensive Relicensing Settlement Agreement and the new 50-year license for the Niagara Power Project.  HIPs were identified and prioritized with the help of the Niagara Ecological Standing Committee (ESC) which is composed of local groups and governmental agencies.  One of the HIPs involves enhancing the nesting habitat of the Common Tern (Sterna hirundo) within Buffalo Harbor.

The Common Tern is a state-listed threatened species whose numbers have declined primarily due to loss of suitable nesting habitat.  In Buffalo Harbor, Common Terns nest on three breakwaters.  The number of nesting pairs of terns on these three breakwaters comprises the largest tern colony in the Great Lakes.  Although terns nest in great numbers on these concrete breakwaters, productivity of these nests is often low due to of a lack suitable nesting substrate.  The goal of the Common Tern HIP is to provide suitable and stable pea gravel nesting substrate on the Buffalo Harbor breakwaters to help increase tern breeding productivity and aid the recovery of this threatened species.  In 2009, two experimental habitat improvements were made to tern nesting habitat in Buffalo Harbor.  The first improvement involved the installation of a containment structure, perimeter fence and gravel substrate on an existing cement-surfaced breakwater which terns use as a nesting site.  The second experimental improvement was the creation of new nesting habitat on a barge moored to a Buffalo Harbor breakwater.  Both of these enhancements successfully provided suitable and productive nesting habitat for Common Terns in 2009 (Riveredge Associates, 2010).  The 2009 results determined that the breakwater enhancement was a more effective long-term method of restoring this threatened species (Riveredge Associates, 2010).

In 2010, the gravel filled containment structure on the breakwater was again monitored for use by nesting terns and was again successful at providing productive habitat (Riveredge Associates, 2011).  The demonstrated success of this enhancement served as a model and three additional enhancements were constructed on Buffalo Harbor breakwaters after the breeding season in the fall of 2010.  The completion of these additional enhancements marked the end of the construction phase of the Common Tern HIP.  In total, approximately 10,570 square feet of enhanced nesting area was created for terns (Table 1-1) on the breakwaters of Buffalo Harbor (Figure 1-1).  All enhancements were monitored during the 2011 breeding season, the first year of five years of post-construction monitoring of tern nesting.

This report summarizes the number of Common Tern nests and their productivity on the improved nesting habitat during 2011.

Table 1-1.  Locations and Area of Enhancements Completed in 2009 and 2010

Buffalo Harbor Breakwater

Other Names for this Breakwater

Portion of Breakwater

Approximate Area (square feet)

First Year Enhancement Available for Nesting Terns

Old Breakwater North

Short

South end

2,100

2009

Old Breakwater North

Short

North end

3,175

2011

Old Breakwater South

South

North end

2,970

2011

North Breakwater

Donnelly’s Breakwall

South end

2,325

2011

Total Enhanced Nesting Area

10,570

 

 

 

North

Figure 1-1. Location of Common Tern HIP Enhancements in Buffalo Harbor

1.0       BACKGROUND

In the Great Lakes region, the Common Tern is considered an endangered species in Ohio, Illinois, Wisconsin and Vermont; a threatened species in New York, Michigan and Minnesota, and an extirpated species in Pennsylvania and Indiana (Cuthbert et al., 2003).

The New York State Department of Environmental Conservation (NYSDEC) has monitored and managed inland Common Tern colonies on the St. Lawrence River, Oneida Lake, and the Niagara Frontier since the late-1980s.  The decline in New York’s inland tern population and the low number of terns currently nesting on New York’s Great Lakes can be attributed to the loss of nesting habitat and low breeding productivity due to predation, poor nesting substrate, and human disturbance.  The loss of nesting habitat is primarily due to an increase in Ring-billed Gulls.

Since 1990, Riveredge Associates (Riveredge) has managed St. Lawrence River Common Tern colonies in an attempt to increase the number of nesting pairs of terns in the region.  In 2004, Riveredge Associates was contracted by NYSDEC to monitor and manage Common Tern colonies in Buffalo Harbor and the Niagara River as well (Harper and Adams, 2005; Harper et al., 2006, 2007, 2008, 2010).  Riveredge and NYSDEC management efforts have attempted to increase the amount of available nesting habitat for terns, decrease the amount of competition for nest sites with gulls, decrease the amount of predation on adults, chicks and eggs, and increase public awareness to reduce human disturbance at tern nesting sites.

1.1     Tern Nesting and Nesting Monitoring

On the Niagara Frontier, Common Terns nest on breakwaters in Buffalo Harbor and potable water intakes and power tower cribs on the upper Niagara River.  Annual monitoring of Common Tern nesting on the Niagara Frontier was started in 1986 (Adams and Batcheller, 1987) and conducted almost annually since.  Riveredge was contracted by NYSDEC to conduct the monitoring of Common Tern nesting colonies on the Niagara Frontier for five years from 2004 through 2008.  In 2009, 2010, and again in 2011, Riveredge was contracted by NYPA to monitor the Common Tern habitat enhancements in Buffalo Harbor as part of NYPA’s Common Tern HIP.  In 2011, Riveredge also assisted NYSDEC with the monitoring and management of the other Niagara tern colonies as well.

Common Terns have nested at 13 sites on eastern Lake Erie and the upper Niagara River since 1986 (Harper et al., 2008).  In and near Buffalo Harbor, these sites have included breakwaters and lighthouses such as the North Breakwater (also called Donnelly’s Breakwall), Reef Lighthouse, Old Breakwater North (also called Short Breakwater), and Old Breakwater South (also called South Breakwater).  On the Niagara River these sites have included potable water intake structures, power tower cribs, and islands associated with water control structures for generating hydroelectric power.

During the last ten years (2002-2011) terns have nested at nine of these sites in Buffalo Harbor and on the Niagara River.  Terns were displaced from four nesting sites by gulls and cormorants.  All current tern nesting sites on the Niagara Frontier are artificial structures such as breakwaters, power tower cribs, and water intakes.

The majority of Common Terns nest on three Buffalo Harbor breakwaters (North Breakwater, Old Breakwater North, Old Breakwater South).  These breakwaters are multi-level structures of concrete and armor stone.  Prior to the implementation of this HIP, the nesting substrate was composed largely of broken concrete chips where the breakwaters are weathering.  There was little or no cover on these structures, and tern nests and chicks were exposed to wind, waves, and weather.  The sides of these concrete breakwaters are vertical, and chicks that fall off the breakwater when disturbed or frightened perish because they cannot re-access the structure.

1.2     Recent Tern Management Efforts in Buffalo Harbor

Since 2004, tern management activities have included the construction of gravel nesting boxes, the installation of perimeter fences, the deployment of chick shelters, and the posting of informational signs on the Buffalo Harbor breakwaters (Harper and Adams, 2005, Harper et al., 2006, 2007, 2008, 2010; Riveredge Associates, 2010, 2011).  Gravel nesting boxes were built to provide better nesting substrate for terns and to increase egg hatching and chick fledging rates.  Temporary nesting boxes were built and installed on each of the three Buffalo Harbor breakwaters in one or more years from 2004 to 2008 (Harper and Adams, 2005; Harper et al., 2006, 2007, 2008), and the improvements described in Section 1.0 were installed in 2009 and 2010.  Plastic perimeter fencing was installed to increase chick survivorship by preventing chicks from jumping off the structures.  Plywood chick shelters were deployed to protect tern chicks from weather, territorial adults, and predators, and to encourage chicks to remain near their nest for a longer period of time.  Finally, informational signs were posted to inform the public of the nesting terns and to limit human disturbance.  Information on the signs included:  NYSDEC Restricted Area, a list of the New York State and Federal Statutes prohibiting the disturbance of Common Terns and a statement that the tern is a designated threatened species under New York State Environmental Conservation Law.  These signs were posted because human disturbance can cause a great deal of chick mortality on the Buffalo Harbor breakwaters.  If anglers or recreational boaters approach the breakwaters too closely, chicks may panic and run, becoming separated from their parents or fall off the structures and perish. 

2.0       METHODS

2.1     Annual Operation and Maintenance of Enhanced Areas

Operation and Maintenance of the Common Tern HIP is conducted as described in Kleinschmidt Associates and Riveredge Associates (2011a).  In April 2011, before terns were nesting, the four enhanced areas of the Buffalo Harbor breakwaters were inspected to determine maintenance needs.  In addition, 2x6 lumber, 1x3 lath, 3/16” mesh plastic fencing, driftwood, and chick shelters were transported to each area to prepare them for the nesting season.  The lumber and fencing were used to divide the enhanced area into subsections.  Boards were screwed together and lath uprights and tensioning rope were used to support the plastic fencing for interior dividers.  Dividing each nesting area into subsections facilitates counting nests and chicks and prevents chicks from moving too far from their natal nest site during the breeding season.  A plastic perimeter fence was installed to prevent chicks from jumping off the nesting area when disturbed and to reduce the chance chicks might be blown off the structure by strong winds.  Gravel that had been displaced by winter storms was raked and shoveled back to the edge of the containment frame on the lake side of the breakwater so that no areas of bare cement remained.  Driftwood was placed on the gravel to provide additional structure and separation among nesting terns.  As tern eggs began to hatch, chicks shelters were placed adjacent to nests to provide cover for chicks from adverse weather and predators.

The specific condition of the structure in 2011 is described in Results Section 4.1.

2.2     Monitoring of Enhanced Nesting Areas

In 2011, Riveredge Associates monitored the tern nesting habitat improvement constructed in 2009 and 2010 on the three breakwaters in Buffalo Harbor.  These enhancements provided approximately 10,570 square feet of enhanced nesting area for terns (Table 1-1).

The number and productivity of Common Tern nests on the enhanced areas of the breakwaters were documented through this monitoring effort.  This site was surveyed from late April through late-July.  Monitoring followed the methods used for recent surveys (Harper et al., 2010; Riveredge Associates, 2010, 2011; Kleinschmidt Associates and Riveredge Associates, 2011b) and were consistent with the “Protocol for Surveying, Monitoring and Managing at Common Tern Colonies in Upstate New York” developed by NYSDEC (NYSDEC, 2004).  Monitoring activities were coordinated with NYSDEC.

Tern colonies were surveyed approximately weekly as weather and colony conditions permitted.  Two to eight people participated in each site survey.  During periods where tern chicks were highly mobile, the frequency of colony surveys was reduced to limit disturbance.  Surveys were not conducted on windy days when older chicks are close to flying age.  Chicks over 15 days old can be blown off the colony simply by opening their partially feathered wings.  At this age, their flight feathers are long but the chicks are not yet capable of flight.  If strong winds blow the chicks off the colony they fall in the water and die.  Mid-to-late June surveys were often shortened or canceled due to the potential to lose a great number of chicks off the breakwaters.

Field notes collected during each monitoring event included the date of each observation, general weather conditions, the number of nests counted, the number of live chicks and eggs present, the number of dead chicks and broken eggs present, and other pertinent information.  Methods used were similar to methods previously used for monitoring Common Terns in Buffalo Harbor by NYSDEC (e.g., Harper et al., 2008).

On each survey, individual nests were numbered with permanent marker and the numbers of eggs or chicks in the nest recorded.  Selected nests in each colony were monitored to determine the number of chicks that hatched and fledged.  On each survey, live chicks were counted.  Dead chicks were counted and removed from the colony.

A subset of tern chicks was banded with incoloy (stainless steel alloy) leg bands.  Chicks were banded at approximately five days of age and older.  Efforts were made to band all chicks within selected sections of the enhancement area of the breakwater to provide an accurate total chick count and to provide data on productivity, survivorship, and post-fledging dispersal.

Monitoring of tern nests, productivity, and chick survivorship on the enhanced areas was also conducted with the use of time-lapse and motion-triggered cameras.  These cameras were deployed in an effort to identify the predator or predators that have lowered tern breeding productivity in previous years (Riveredge 2010, 2011).  Because a mink was observed on the North Breakwater after the breeding season in 2010 and was suspected in the death of tern chicks on the Old Breakwater South, a nuisance mink permit was issued by NYSDEC and mink traps were deployed on these two breakwaters.

2.3     Data Analysis

The number of tern nests and the number of tern chicks that survived to fledging were used to assess the success of the enhanced nesting areas.  Average productivity was calculated by counting the total number of tern chicks fledged and dividing this value by the number of tern nests that produced these chicks to calculate the average number of chicks fledged per nest.  Productivity for this year was compared to the productivity of these breakwaters for previous years (e.g., Harper et al. 2010; Riveredge Associates, 2010, 2011) and used to assess the success of the tern nesting habitat improvements.  In addition to determining productivity, maintenance and monitoring needs (e.g. number of shelters, needed repairs) were also noted to assist with future implementation of the Common Tern HIP.

3.0       RESULTS

3.1     Maintenance of Enhanced Areas

The first inspection of the enhanced areas of the breakwaters was conducted on April 9, before the Niagara River Ice Boom was removed for the season (Figure 4-1).  All of the containment frames and gravel were found in good condition.  On the lake side of each structure, small amounts of gravel had been moved away from the edge of the containment frame by winter storms, but much less than in the spring of 2010.  Where needed, the gravel was raked back to the edge of the containment frame to provide nesting substrate of suitable depth. As in 2010, a goose nest was removed from the tern nesting area on Old Breakwater North so interior dividers could be installed and because geese can inhibit tern nesting by trampling nests and eating eggs.  Resident goose nests were removed under the U.S. Fish and Wildlife Service’s Resident Canada Goose Registration permit program.

Perimeter fencing and interior fencing was installed at each of the four enhanced areas (Figure 4-2).  The circular end cell on the south end of the Old Breakwater North was divided into six pie-shaped sections using 2x6 lumber and plastic perimeter fencing.  The long, rectangular enhancement at the north end of the Old Breakwater North was divided into 11 rectangles of approximately equal area.  The enhanced area of the Old Breakwater South was divided into four sections with interior dividers.  The rectangular enhanced area on the North Breakwater was divided into five sections of approximately equal area.  At each site, driftwood and/or chick shelters were added to provide structure and cover.  The interior dividers and chick shelters were clearly visible on publically available aerial photos on the internet (such as those at www.bing.com taken in April) and in aerial photos taken in May (Figure 4-3).

All fencing was installed by April 18.  On April 18, the harbor still contained significant amounts of ice.  The harbor was largely ice free a few days later.

In late April, strong winds swept across Lake Erie and damaged perimeter fencing and gravel.  This fencing had to be repaired and the gravel raked back to the edge of the containment frames.  This event occurred during the nest initiation period and affected the timing and number of tern nests.

 

Figure 4-1. Early April Conditions at Old Breakwater South

 

Figure 4-2. Installation of Perimeter Fence and Interior Dividers

 

North Breakwater

Old Breakwater South

Old Breakwater North

Figure 4-3. Aerial View of Enhanced Areas with Nesting Terns (May 2011)

3.1     Number of Nests

A small number of terns (~25) were present on Buffalo Harbor breakwaters on April 9 when operation and maintenance activities began.  By April 18, there were several hundred adult terns on the breakwaters, and nest scrapes were visible on April 19.  The first eggs were laid in late April, and the number of tern nests increased rapidly through late April and early May.  However, weather during the mid-to-late April nest initiation period was characterized by strong winds and waves in Buffalo Harbor.  From April 15 to April 30, 75% of days had wind gusts over 25 miles per hour (mph) as measured at the Buffalo Airport.  On April 28, wind gusts reached 53 mph, generating large waves on Lake Erie and in Buffalo Harbor and causing wave splash to reach even the highest portions of the Buffalo Harbor breakwaters.  This storm washed nests away from the upwind side of the breakwaters, particularly the North Breakwater, where approximately 25% of all nests were destroyed.  In addition, perimeter fencing was torn, and gravel and chick shelters along the edge of the containment frame were displaced towards the middle of the breakwater.  Following the storm, the fencing was repaired and gravel was raked to the edge of the containment frames.  Terns whose nests were destroyed likely attempted to nest again, since this storm event occurred early in the nesting season.

An Annual Index Count of all tern nests is conducted each year at the peak of incubation and the start of egg hatching, and this year it was conducted on May 19, 2011.  The number of tern nests on the Buffalo Harbor breakwaters on the peak survey date was 1,888, a new record high since monitoring began 25 years ago (in 1986).  Just over half of these nests (1,030 of 1,888 or 54.6%) were located on the Old Breakwater North (Table 4-1).  The remaining nests were located on the North Breakwater (N=569) and on the Old Breakwater South (N=289) (Table 4-1).

The number of nests on the Old Breakwater North in 2011 (N=1,030) was more than twice the number of nests (N=487) present in 2008 before NYPA enhancements of this breakwater were implemented.  The number of nests on the Old Breakwater South in 2011 (N=289) was more than six times greater than the number of nests in 2010 (N=47).  In contrast, the number of nests on the North Breakwater was lower in 2011 than in 2010, dropping from 906 nests to 569 nests, a decrease of 37.2%.

Table 4-1. Number of Tern Nests During Annual Index Count in Buffalo Harbor, 2004-2011

Buffalo Harbor Site

2004

2005

2006

2007

2008

2009

2010

2011

North Breakwater

796

975

659

747

948

663

906

5691

Nesting Barge (installed in 2009 only)

-

-

-

-

-

224

-

-

Old Breakwater North

183

317

4502

419

487

683

882

1,030

Old Breakwater South

49

84

88

71

42

30

47

289

Buffalo Harbor Total 3:

1,028

1,376

1,197

1,237

1,477

1,600

1,835

1,888

1 These nests were all abandoned later in season due to mink depredation

2 Estimated value

3 2009 and 2010 data for sites not monitored by Riveredge was provided by NYSDEC

 

Figure 4-4. Late April Storm Damage on the North Breakwater

 

Figure 4-5. Terns Establishing Territories and Incubating Eggs

Figure 4-6. Number of Tern Nests During Annual Index Counts on Buffalo Harbor Breakwaters

3.2     Productivity

Productivity and factors that could potentially affect productivity were monitored through nest surveys, chick banding, and predator monitoring using time-lapse and motion-triggered cameras, and predator traps.  The peak period of tern hatching occurred in late May and early June, similar to 2010.  On May 30, a large number of depredated tern eggs were found cached outside the containment frame on the North Breakwater.  Food caching is a behavior characteristic of mink.  The behavior of terns on this breakwater appeared to be abnormal; birds appeared to be more nervous than observed during previous visits in the season (i.e., they would flush off of nests sooner, or would act less defensively to protect their nests when approached by biologists), potentially suggesting previous disturbance by a mammalian predator.

By the first week of June, the first wave of hatching tern chicks were old enough to band.  Chick banding was performed because it facilitates accurate chick counts, measurements of chick survivorship, and the determination of breeding productivity.  The first major banding effort was conducted over five days during the first week of June (June 3, 4, 5, 6, 7).  During this period, 1,313 tern chicks were banded.  Of this total, most (1,285 tern chicks) were banded on Old Breakwaters North and South.

On the North Breakwater, only 28 tern chicks were banded.  However, an additional 592 tern chicks were found dead on the North Breakwater, as well as hundreds of unhatched abandoned eggs.  The majority of the dead chicks were 3 days old or less when they died.  These chicks were likely killed by mink depredation and by the abandonment of nests at night by adult terns, leaving eggs and chicks exposed to weather and low temperatures.  Adult terns often abandon nests at night if there is a predator capable of killing an adult in a colony.  Terns may live to be more than 20 years old and adults generally sacrifice their eggs or chicks before they take the risk of being killed themselves on the nest at night.  On June 5, there were only 46 live chicks on the North Breakwater, and all of these perished within the next week.  By mid-June, all 569 tern nests on the North Breakwater had been abandoned and no adult terns were present.  No tern chicks successfully fledged from this site in 2011; productivity of terns nesting on the North Breakwater in 2011 was 0.0.

On the Old Breakwater North and Old Breakwater South, the total number of chicks present in early June was divided by the number of nests present on May 19 to calculate the initial number of chicks hatched per nest for early breeding terns at these sites.  The number of chicks later found dead was subtracted from this to determine the number of chicks fledged per nest.

Early breeding terns that successfully hatched eggs had excellent chick survivorship on the Old Breakwater North and Old Breakwater South.  Banded chicks had an average of 93% survivorship on each breakwater.  Average productivity summed across each subsection of enhanced areas of the Old Breakwater North and Old Breakwater South ranged from 1.8 to 2.0 chicks fledged per nest (Table 4.2), which isthe highest average productivity ever recorded for the Buffalo Harbor breakwaters.

Although average productivity was at an all-time high for the 2011 nesting season, the productivity of later breeding terns was reduced by lower survivorship of late hatching chicks.  Chicks that were banded in late June averaged 77% survivorship, and chicks that were banded in mid-July had 55% survivorship.

Terns continued to breed in Buffalo Harbor later in the summer than ever recorded before.  On August 24, there were still eight chicks incapable of flight on the Old Breakwater South, which is by far the latest recorded date for tern chicks in Buffalo Harbor in 25 years of monitoring.  Additionally in August, approximately 20 young tern chicks had been killed and cached on the Old Breakwater South.  The tern chicks had been eaten and cached in a manner that implicated mink as the predator.

In 2011, mink depredation reduced tern productivity on the Buffalo Harbor breakwaters and caused all nests (N=569) on the North Breakwater to fail.  In an effort to control the effects of mink depredation on terns, NYSDEC issued a nuisance mink trapping permit and two mink were removed from the breakwaters in July (one each from North Breakwater and Old Breakwater South).  Nonetheless, mink depredation had significant negative effects on tern breeding in Buffalo Harbor in 2011.  Mink depredation occurred at times and at sites not monitored by time-lapse and motion-triggered cameras.  These cameras were deployed on the Old Breakwater South from April to July and recorded over 1,000,000 photographs.  Mink predation occurred on the North Breakwater in May and on the Old Breakwater South in August.  No mink predation was captured by the cameras.

An additional factor in the lower survivorship of older chicks late in the season could be related to reduced food availability and higher heat stress, and has been observed in previous years as well.  In addition, younger, less experienced adults tend to breed later in the year, and these birds commonly produce fewer chicks than the early-nesting older adults (Nisbet et al., 2002).

In total, 2,883 tern chicks were banded in Buffalo Harbor in 2011.  Of these, 680 banded chicks were found dead later in the season.  The remaining 2,203 tern chicks likely fledged from the Buffalo Harbor breakwaters.  Preliminary data from other tern researchers in the Great Lakes suggests that no other Great Lakes tern colony successfully produced more chicks in 2011.

Table 4-2. Tern Productivity on Buffalo Harbor Breakwaters 2004-2011

Buffalo Harbor Site 1

2004

2005

2006

2007

2008

2009

2010

2011

 

North Breakwater 2

Overall (entire breakwater) 3

0.5

0.9

0.9

0.9

0.8

-

0.0

0.0

Old Breakwater North 2

Overall (entire breakwater) 3

0.3

0.5

-

-

-

-

0.0

-

End Cell only (fenced and partially graveled in 2007-2008; fully graveled starting 2009)

-

-

-

1.4

1.0

1.4

1.6

2.0

Crest section (north end; fully graveled starting 2011)

 

 

 

 

 

 

 

1.8

Old Breakwater South

Double end cell (partially graveled in 2009, 2010; fully graveled starting 2011)

 

 

 

 

 

 

0.0

1.8

 

1 2009 and 2010 data for sites not monitored by Riveredge were provided by NYSDEC

2 Cells with dashes mean that the site was not monitored in detail that year

3 Overall average may or may not include other fenced areas

4.0       DISCUSSION

The primary goal of the Common Tern HIP is to provide long-term stable substrate that can be used by terns for many years with little maintenance.  The containment frames constructed in spring 2009 and fall 2010 showed no damage from winter storms in 2010 and 2011.  The gravel in the containment frames was only slightly displaced by winter storms and was easily redistributed with simple hand tools (shovels and rakes) in the spring.  Repairs to the perimeter fence following spring storms were also readily accomplished.

The habitat enhancements of the Common Tern HIP were very successful at attracting large numbers of nesting terns to the high-quality nesting substrate provided on the Buffalo Harbor breakwaters.  The number of tern nests and the average productivity of terns nesting on these sites both hit new record highs in 2011, the highest ever recorded in 25 years of Buffalo Harbor tern nesting monitoring (Figure 5.1).

Since the implementation of the NYPA Common Tern HIP in 2009, both the total number of tern nests in Buffalo Harbor and the average productivity of these nests have increased dramatically.  Averaged across all sections of the enhanced nesting areas, tern productivity ranged from 1.8 to 2.0 chicks fledged per nest on the Old Breakwater South and Old Breakwater North. Old Breakwater North continues to be the most productive of the Buffalo Harbor breakwaters.  Although tern nesting productivity was good at this site in 2007 and 2008 when partially graveled, it has increased substantially since enhancement via the HIP began in 2009.    The newly enhanced habitat of the elevated crest section on the north end of the breakwater did very well in its first year of 2011, with a productivity rate higher than previously recorded on this breakwater. 

This year, as in 2009 and 2010, strong spring storms reduced the tern nesting productivity rate on the Buffalo Harbor breakwaters with very high winds (50-75 mph in 2011 and 2010).  In 2010, the only tern chicks that fledged in all of Buffalo Harbor came from nests on the enhanced areas of the NYPA HIP (Riveredge Associates, 2011).  Although early spring storms had some effect on tern nest numbers and productivity in 2011, the containment frames and pea gravel of the NYPA HIP have provided excellent habitat for tern nesting and the overall average productivity has again exceeded that recorded in previous years.

Figure 5-1. Number of Tern Nests During The Annual Index Count on Buffalo Harbor Breakwaters Over Last Ten Years (2002-2011)

In 2010, tern nests failed completely on the Old Breakwater South due to an unknown predator.  In 2011, predator disturbance was a major factor in the failure of tern nesting on North Breakwater. New evidence obtained in 2011 identified this predator as a mink.  In 2011, mink depredation at these locations occurred primarily late in the breeding season (late July and early August), thereby affecting late-season productivity.  Two mink were trapped and removed in July in an effort to aid the success of terns nesting on the breakwaters.

Average productivity values observed after the Common Tern HIP improvements are considerably higher than those recorded at most Niagara Frontier tern nesting sites from 1986 to 2003 (0.3 to 0.4 chicks fledged per nest), a period when most sites did not have added nesting gravel (Harper and Adams, 2005).

In total, the Common Tern HIP has created over 10,000 square feet of improved tern nesting habitat on the Buffalo Harbor breakwaters.  The construction of these nesting habitat improvements marks the end of the implementation phase of the Common Tern HIP.  Monitoring of tern nesting on these improved nesting areas started in 2011 and will continue for five years through 2015.  After these five years of nest monitoring, the structures of the HIP will be monitored annually for maintenance and repair.

For the last three years, the majority of tern chicks fledged from the Buffalo Harbor breakwaters did so from nests on the gravel provided by the Common Tern HIP.  These birds will migrate to Central and South America during the winter and return to the Buffalo Harbor breakwaters in future years to breed themselves.  The Common Tern HIP will provide critically needed high quality nesting habitat for these birds and assist with the recovery of this state-listed threatened species.

5.0       REFERENCES

Adams, C. and G. R. Batcheller.

 1988. Status

 of Common Terns on the Buffalo Harbor and upper Niagara River: final report FY 1987-88. New York State Department of Environmental Conservation, Bureau of Wildlife, Region 9, Buffalo, New York. 55 pp.

Cuthbert, F. J., Wires, L. R. and K. Timmerman. 2003. Status assessment and conservation recommendations for the Common Tern (Sterna hirundo) in the Great Lakes region. U.S. Department of the Interior, Fish and Wildlife Service, Fort Snelling, Minnesota. 95 pp.

Harper, L. H. and C. M. Adams. 2005. Status assessment of Common Terns on the Buffalo Harbor and Niagara River: 2004 breeding season final report. Report prepared by Riveredge Associates for the New York State Department of Environmental Conservation, Bureau of Fish, Wildlife, and Marine Resources, Albany, New York. 26 pp.

Harper, L. H., L. J. Harper, M. Promowicz, and C. M. Adams. 2006. Buffalo Harbor and Niagara River Common Tern status assessment and management: 2005 nesting season final report. Final report prepared by Riveredge Associates for the Nongame and Habitat Unit, New York State Department of Environmental Conservation, Albany, New York. January 31, 2006. 23 pp.

Harper, L. H., L. J. Harper, M. Promowicz, and C. M. Adams. 2007. Status assessment and management of Common Terns on the Buffalo Harbor and Niagara River: 2006 nesting season final report. Final report prepared by Riveredge Associates for the Nongame and Habitat Unit, New York State Department of Environmental Conservation, Albany, New York. February 28, 2007. 31 pp.

Harper, L. H., L. J. Harper, M. Wait, M. Promowicz, and C. M. Adams. 2008. Niagara Frontier Common Tern conservation and management project: 2007 nesting season final report. Final report prepared by Riveredge Associates for the Nongame and Habitat Unit, New York State Department of Environmental Conservation, Albany, New York. March 25, 2008. 39 pp.

Harper, L. H., L. J. Harper, P. Herbert, and C. M. Adams. 2010. Niagara Frontier Common Tern conservation and management project: 2008 nesting season final report. Final report prepared by Riveredge Associates for the Nongame and Habitat Unit, New York State Department of Environmental Conservation, Albany, New York. February 26, 2010. 26 pp.

Kleinschmidt Associates and Riveredge Associates.  2011a.  Common Tern Habitat Improvement Project: Operation and Maintenance Plan. Draft Plan Prepared by Kleinschmidt Associates and Riveredge Associates for the New York Power Authority. September 2011.  10 pp.

Kleinschmidt Associates and Riveredge Associates.  2011b.  Common Tern Habitat Improvement Project: 5-Year Biological Monitoring Plan. Draft Plan Prepared by Kleinschmidt Associates and Riveredge Associates for the New York Power Authority. September 2011. 8 pp.

New York State Department of Environmental Conservation (DEC). 2004. Protocol for surveying, monitoring and managing at Common Tern colonies in upstate New York. Draft document released by Nongame and Habitat Unit, Albany. February 2004. 2 pp.

Nisbet, I. C. T. 2002. Common Tern (Sterna hirundo). In The Birds of North America, No. 618 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, Pennsylvania. 40 pp.

Riveredge Associates. 2010. Common Tern Habitat Improvement Project: 2009 Buffalo Harbor Tern Colony Enhancements and Status Assessment. Final Report prepared by Riveredge Associates for the New York Power Authority. March 2010. 24 pp.

Riveredge Associates. 2011. Common Tern Habitat Improvement Project: 2010 Buffalo Harbor Tern Colony Enhancements and Status Assessment. Final Report prepared by Riveredge Associates for the New York Power Authority. January 2011. 26 pp.