Photo by Ron Logan

View a slide show of photos taken by staff, volunteers, landowners, and other partners.

Introduction

Since 2007, the great blue heron (Ardea herodias) has been listed inMaine as a Species of Special Concern.  While this status has no regulatory significance, is does signify possible decline and that more information is necessary to accurately determine the population trend.  Thus, an effort was initiated in 2009 to better track great blue heron colonies and the number of nesting pairs in the state, both on coastal islands and at inland sites.

In 2009, MDIFW conducted a nearly statewide census of all colonial wading birds, with emphasis on the great blue heron.  With the help of pilots from the Warden Service and Forest Service, biologists conducted over 60 hours of aerial surveys.  Over 180 historical locations were checked, and 80 new sites were discovered during the surveys or as a result of information provided by the public or other biologists (Figure 1).  In addition to aerial surveys, biologists visited 38 colony sites on the ground to help verify colony locations and to gather more precise counts of active nests.  Survey efforts revealed 1,071 nesting pairs of great blue herons at 83 colonies.  Since 2009, 33 additional colonies have been discovered or reported to MDIFW (Figure 1).

Aerial surveys are the most efficient way to assess great blue heron colony activity on a large scale.  Unfortunately, they are also expensive and MDIFW does not have the financial means to collect this level of data on an annual basis.  In order to continue building our knowledge of wading bird colonies inMaineover time, MDIFW began a volunteer colony monitoring program in 2009 called the Heron Observation Network, or HERON for short.  HERON volunteers monitor colonies by visiting known current or historic nesting locations at least once during the breeding season and recording the species, number of nests active and inactive, and in some cases the number of nestlings or fledglings.

In 2009, 45 HERON volunteers signed up to monitor 66 colonies.  Twenty of these volunteers ended up following through with their commitment and turned in observation data for 28 colonies.  Of those that turned in data, 15 also tracked and reported the amount of time they committed, totaling 186 hours.

2010 Survey and Monitoring Efforts

Survey and monitoring efforts in 2010 consisted of biologists and volunteers monitoring 94 great blue heron colonies, of which 60 were active with approximately 898 pairs (Figure 2).  The Heron Observation Network grew in 2010: 64 volunteers signed up to monitor 80 colonies; 42 volunteers turned in observation data for 52 colonies; and 22 volunteers recorded 148.5 hours.  In spite of this growth, there were 19 colonies that had been active in 2009 that did not get surveyed in 2010 due to lack of sufficient staff time, volunteers, or funding for aerial surveys; thus it is unknown whether or not these colonies were active in 2010.

2011 Survey and Monitoring Efforts

During the 2011 breeding season, biologists and volunteers monitored 90 great blue heron colonies, of which 54 were active with approximately 783 pairs (Figure 3).  Thirty-four colonies containing 77 nests were also monitored but did not show nesting activity.  HERON continued to grow in 2011 with 76 volunteers who signed up to monitor 111 colonies; 50 volunteers who turned in observation data for 75 colonies; and 28 volunteers who recorded 255 hours.  Even with this amount of effort, there were 31 out of 100 great blue heron colonies that were active in 2009 and/or 2010 that did not get surveyed in 2011 due to lack of sufficient staff time, volunteers, or funding for aerial surveys.

Importance of Volunteers

In three years, the HERON program has grown significantly and has provided “free” data that will be used to assess the population trend for Maine’s great blue herons (Figures 4 and 5).  An additional benefit of this program has been the use of volunteer time as a match for federal funding such as State Wildlife Grants (SWG).  These federal funds often require a non-federal match ratio of 50:50.  Volunteer time that is properly tracked and recorded is assigned an hourly rate of worth, is included in the full cost of the project, and is counted as in-kind match for the funds needs to support survey and monitoring efforts such as aerial surveys and vehicles for on the ground work by biologists and contractors.

Volunteer time will also be used this winter and spring as a match for SWG funds to hire a contractor to enter data into MDIFW’s ETSC (Endangered, Threatened and Special Concern) database and GIS.  We hope to use volunteer time as a match for funding an aerial survey in 2015.

Initial Trend

The 2010 and 2011 field seasons did not cover all known colonies across the state, thus we cannot determine a statewide population trend at this time.  However, there were 55 colonies that were monitored each of the three years (2009, 2010, and 2011), and colony occupation among the 55 sites declined by 26% (Figure 6).  It is unknown if this decline is simply an artifact of herons changing their colony locations, or if it is an indication of a true decline in nesting activity.  This cannot be determined without complete knowledge of all colonies across the state or another method for estimating the nesting population of great blue herons.

Survey for Estimating Statewide Population

It may never be possible to survey the entire state for nesting great blue herons in one year because they occupy such a wide variety of habitats: snags in wetlands, live trees in uplands both adjacent to and far removed from lakes and wetlands, and coastal islands.  Nearly the entire state of Maine is considered “potential nesting habitat”.  For this reason, we are working on developing a survey that will sample the state and use known colony sites to develop a model for estimating the breeding population of great blue herons.  This survey is planned for 2015.

Between Now and 2015

Over the next three years, we hope to increase monitoring efforts across the state with the help of HERON volunteers.  Every year, important colonies do not get monitored due to a lack of volunteers in the right parts of the state.  In addition, we hope to learn of new colony locations to add to our database and future monitoring.  A press release will be issued in early spring of each year to recruit new volunteers and to solicit new colony information.

Many colonies do not get monitored due to volunteers who sign up to monitor a site but do not follow through.  We hope to remedy this with more communication in the middle of the breeding season.  If volunteers are unable to monitor the site they sign up for, they simply need to inform MDIFW so someone else can observe the colony before the end of the breeding season.

Volunteer hours will continue to be tracked and recorded by those who complete the necessary paperwork, and will be used to help leverage funds for the planned survey in 2015.

The HERON blog (http://maineheron.wordpress.com) and the HERON Facebook page (http://www.facebook.com/maineheron) will continue to serve as a means to communicate with and educate current volunteers, landowners, and the public.  We plan to increase postings to the blog and Facebook and encourage interactive dialogue through these media in the coming years.

Photo by Deb Dutton

June is when nestlings appear in most great blue heron colonies in Maine.  In Maine, great blue herons lay their eggs anytime between late April and mid-May.  After approximately 27 days of incubation, the nestlings hatch out mostly unfeathered except for pale gray down that appears a bit bushy on the crown.  They weigh less than 2 ounces at hatching and can barely hold their heads up.  Within a week or two they can be seen poking their heads above the edge of the nest bowl, especially when their parents return to the nest to provide food.  Within 7-8 weeks, the nestlings will grow to adult size, weighing in at 4.5 lbs and standing about 3 ft tall.  Check out a video clip of a heron nest with nestlings taken by Deb Dutton on Facebook!

An adult great blue heron arrives ready to feed its nestlings. Photo by Ron Logan.

 [The short article and incredible photos below are from volunteer, Ron Logan, who monitors 4 great blue heron colonies for HERON.]

The season will begin in a couple weeks to monitor my 4 Great Blue Heron colonies. These pictures are from last year and were taken from quite a distance. Generally you can’t get very close to nests, since they are in wetlands and 20 to 50 feet in the air.  If you think feeding your babies was tough, or that dinner table fights with your siblings was a nightmare, imagine what it would be like as a Great Blue Heron.

A nestling pulls at the adults beak as a signal to give up the food. Photo by Ron Logan

This is how it works: First the mother arrives with the meal. She strikes a regal pose and the kids all gather in front her. [Note: Both males and females share feeding duties.]

At some point one of the kids (wise guy, class clown, etc.) reaches up and grabs mom’s beak and pulls her down into the pack, which then resembles a rugby match. [Note: When a nestling grabs the adult's bill, it stimulates the adult to regurgitate its food for its young.]

The adult bends down to give up the food and the nestlings try to get their share. Photo by Ron Logan

You’re seeing it once, but it plays out over and over. Each time the mother stands erect, and then gets pulled down into the rugby scrum.

The adult stands by as the nestlings feed. Photo by Ron Logan

It’s a wonder that all the kids get fed. Inevitably fights break out. [Note: Whether or not the herons view it as a fight, it is instinctive for them to get fed as much food as possible.] In this case, the bird about to fall over backwards, down 50′ into the swamp (remember, he can’t fly yet), regained his balance and lived to enjoy other food fights. I’ve been told, in the south alligators gather under the nests, waiting for the occasional feast from above. [Note: It is not uncommon for nestlings to fall out of nests as a result of losing their balance, getting pushed by nest-mates, getting blown out by a strong wind, or by being frightened by a potential predator. These nestlings most often do not survive the fall.] 

The mother remains regal and detached as this drama plays out. I’m guessing she can’t count anyway.

[Note: Great blue herons hatch asynchronously, meaning that each egg hatches 1-2 days apart.  Thus, the first hatched nestling has an automatic advantage over younger siblings, especially when it comes to winning food fights as described above.  At 4 weeks of age, herons can lift and swallow whole fish dropped by the parents into the nest.  Large fish often result in tug-of-war episodes among sibling herons, with not all coming out as winners.  If the youngest chicks cannot compete well with their siblings for food, they may stop growing and eventually perish.]

[HERON volunteers often witness interesting events when watching their adopted colonies.  I hope to share similar articles and photos provided by vounteers in the future; all will be categorized as "Volunteer View".]

A nestling regains its balance at the edge of the nest. Photo by Ron Logan.

In April 2009 at this colony in downeast Maine, ice-out is not yet complete and the herons have yet to return. Photo by Jonathan Mays.

The snowpack is gradually receding at my house.  A remnant of our first snowman of the winter is poking its head out once more (so that’s where my hat went!).  While I dread the looming mud season that will follow, I am excited that spring is really on its way.  In fact, the Vernal Equinox is just around the corner: March 20^th to be exact.  Besides mud season, the arrival of spring also marks the return of great blue herons to Maine.  Have you seen any herons yet?  Feel free to post here or on Facebook to share your first heron observations of the season.

A volunteer and I watch nesting herons from a distance.

Whether or not you see one of the first herons to arrive in Maine is not important.  What is more important is ensuring that each of our wading bird colonies is being monitored by a member of the Heron Observation Network.  The Heron Observation Network is a network of volunteers who have adopted colonies across the state.  By adopting a colony, volunteers make observations at the colony during the breeding season and report the data back to MDIFW.  Over time, this data will help to reveal population trends of each colonial wading bird species and help guide future management.  

During the nest building stage, a great blue heron brings a twig to its mate. Photo by Al Larson.

MDIFW knows of approximately 100 active great blue heron colonies in Maine and has found volunteers to monitor many of them.  However, there are still approximately 40 colonies that have not been adopted.  Adoption includes a minimum of 1 visit during the peak of the breeding season which is mid-May to mid-June.  For those with the interest and time, additional observations can be made at 2-week intervals in an effort to capture breeding effort and success information for the season.  Observations are only done if disturbance to the nesting birds can be avoided.  Binoculars are necessary, and a scope is often very helpful.  Data recorded include the number of active and inactive nests, the breeding stage of each nest (incubation, nestling, fledgling), and the number of nestlings and fledglings seen.

 Below is a list of the towns where colonies needing adoption are located.  Contact me if you are interested in adopting a colony or if you know of a colony that we may not yet know about.

Great blue heron. Photo by Ron Logan.

The great blue heron is often touted as one of the most widespread and adaptable birds in North America.  Here in Maine they are certainly widespread, but recent data has suggested a decline in their breeding population especially along the coast.  Concerns over a population decline prompted the Maine Dept. of Inland Fisheries and Wildlife to conduct a comprehensive survey of breeding colonies in 2009, and to begin a statewide adopt-a-colony program called the Heron Observation Network.  Join me at one of the following locations to learn more about Maine’s largest colonial wading bird…

Great blue heron colony with approximately 30 active nests. Photo by Leigh Macmillen Hayes.

 

Great blue heron "condo".

Sheepscot Valley Conservation Association

[About the image above:  This great blue heron was made by my father, Sam D'Auria, out of several different hardwoods, an art form called intarsia.]

As 2010 draws to a close, I’d like to take a few moments to thank all those who have helped to make the 2nd year of the Heron Observation Network a success.  To date, I’ve received data from 41 volunteers who monitored 52 great blue heron colonies in 2010.  These volunteers contributed 148.5 hours of their time to increase our understanding of the status of the great blue heron in Maine.  THANK YOU!  In addition, members of the public reported more than 13 new colonies, thereby increasing our ability to track the statewide population.  Many thanks to all the landowners who have provided staff and volunteers access to their land for the purpose of monitoring great blue heron colonies.  Not only are the landowners providing access, but they are also providing in one way or another disturbance-free habitat that is appealing to herons for nesting.

I’ve enjoyed meeting and communicating with our volunteers and landowners, and look forward to additional interactions in the coming year.  There are always more colonies that need volunteer monitors and there are likely more colonies to be discovered.  If you know of a wading bird colony, please don’t hesitate to report it to me.  Or, if you’d like to join the Heron Observation Network and adopt a colony yourself, please contact me, danielle.dauria@maine.gov, (207) 941-4478.

Best Wishes for a Happy and Healthy New Year!

Logan Labree, Dalton McCaughlin and Rachel Bates measure and record the diameter of a great blue heron nest tree while Skip Walsh (in background) searches for another nest.

On a brisk fall afternoon after most students have headed home from Sebasticook Valley Middle School, 10 students remain.  They each don a hunter orange cap supplied by the school and head outside.  Today’s meeting of the Maine Outdoors Club is a unique one.  They have two guests: Brad Allen and I, both biologists with the Maine Department of Inland Fisheries and Wildlife (MDIF&W).

Though it is hunting season, the students are not going to learn about hunting laws or ethics.  Instead, they will assist with monitoring a great blue heron colony located literally in their back yard, right on school property.

The school district’s great blue heron colony was originally reported to MDIFW by local residents in 2009.  The initial ground visit by biologists last April revealed only six nests, but the breeding season had just begun and the colony was likely not yet fully occupied.  An aerial survey of the site in late June revealed an estimated 30 nests, most containing nestlings.

The Nokomis Regional High School has been doing surveys for black terns [a state endangered species] for MDIFW for over 20 years, so the fact that a heron colony showed up on school district property was very fitting.  The recent startup of the Maine Outdoors Club at the neighboring Sebasticook Valley Middle School, and my involvement as a contact person with MDIFW was also timely. It seemed like a natural fit for the club to ‘adopt’ this colony and monitor it into the future.

Faculty members Skip Walsh and Bernie Welch are co-advisors of the Maine Outdoors Club, which is an after-school program for students who not only have an appreciation for Maine’s wildlife and natural resources but also enjoy fishing, hunting, and other outdoor sports.  The club has about 30 members, who meet as smaller groups twice a week. We met with the group on Nov. 18.

This is what we see when we search a white pine stand for heron nests. Do you see one or more nests?

The ten students split up into three groups, each equipped with a measuring tape, clipboard, GPS unit, plastic bag, and flagging tape.  There was no expectation that the students would see a great blue heron on their outing because the birds finished breeding in August and no longer reside at the colony.  Instead, they were on a mission to find the birds’ conspicuous stick nests.  At each nest tree they recorded the GPS location, the diameter at breast height, tree species, whether the tree was live or dead, and the number of nests in the tree.  Their final task was to look to the ground for heron and prey remains.  Heron and prey remains could be food remains, feathers, eggshells, or even the remains of heron nestlings.  All this work requires a lot of time on the ground within the colony, which during the breeding season would be extremely disturbing to the herons, possibly causing nest failures or complete abandonment of the colony.  In the fall, there is no risk to the birds.

After only an hour in the woods, the three teams were extremely successful.  They located and recorded data on 27 nests in 23 trees, and found heron remains including a skull, mandible, wing bone, pelvic girdle, and feathers; heron eggshells; and fish bones and scales.  The tree data will help biologists better understand heron nesting habitat, and the heron and prey remains will be used in research to determine whether these herons get their nutrients from freshwater or marine sources.  While they likely feed in nearby Nokomis Pond or Sebasticook Lake, marine nutrients could be entering the system if anadromous fish are present in the watershed.  Anadromous fish play an important role in transporting marine nutrients inland.

The great blue heron colony visit was part of the club’s Ecology Program where the students use scientific inquiry and do hands on experiments to become experts in Maine’s wildlife and their habitat.  Working side by side with professional wildlife biologists can leave a lasting impression on the students.  According to Walsh, “They really felt part of something important.  In the short time they had while waiting for their rides home, many of them were on their lap-tops looking up more information about the great blue heron.  As they got into their parent’s cars, they couldn’t wait to tell their parents about their experience.”

[The above article was also printed in the Bangor Daily News on 11/23/2010.]

Cattle egret observed feeding on grasshoppers on Bailey Island in Harpswell. (Photo by Jonathan Mays)

Fall is upon us and winter is certainly not far behind.  [Snow was flying as early as Halloween at my house this year!]  As the cold weather moves in, herons typically move out…of Maine, that is.  I say typically because there are definitely stragglers here and there.  But, what’s more interesting is that after herons breed they typically disperse in all directions before heading south for the winter.  In the scientific literature, this is dubbed “nondirectional wandering.”  This is why we can see such rarities as yellow-crowned night-herons and cattle egrets in the fall in various parts of the state.  We don’t currently have either of these species nesting in the state – at least not that I am aware of.  And they certainly are not known to breed north of Maine.

A few of the most recent sightings of interest have been cattle egrets in Gorham, Harpswell, Burnham, Pittsfield, Belfast, Vinalhaven, Chester, and Easton.  Such an abundance of sightings may suggest nearby breeding, but don’t be fooled so quickly.  The only data I have regarding breeding cattle egrets in Maine is between 1989 and 1995, when up to 3 pairs nested on Stratton Island in Saco Bay.  National Audubon manages this island and keeps record of up to seven species of breeding herons there.

A juvenile yellow-crowned night-heron seen at the Mt Hope Cemetary in Bangor in 2009.

In August of 2009, I had the delight of seeing a juvenile yellow-crowned night-heron right here in Bangor.  Night-herons’ nocturnal habits make them more secretive than other herons and thus they may go unnoticed especially if there is only one pair nesting in an area.  However, as of 2006, the nearest breeding site was in southern New York (Mid-Atlantic/New England/Maritimes Region (MANEM) Waterbird Conservation Plan).  Certainly expansion of the species northward could have occurred since then.  In fact, an extensive tendency for nondirectional wandering in cattle egrets is one of the keys to its successful range expansion from South Africa to North America only 60 years ago.

The reasons for nondirectional wandering are not clearly understood.

Birds may seek foraging areas where competition from other conspecifics (birds of the same species) is reduced.  This makes sense when you consider that a moderately sized colony in Maine of 25 pairs of great blue herons may successfully fledge 75 young.  Where are 50 adults and 75 young going to feed?  Most likely the favorite feeding places of the parents don’t have enough wading room for the youngsters.  Plus, herons can be quite territorial when it comes to prime feeding sites, with age and sex determining who’s dominant.

A cattle egret seen in Easton on November 9th. (Photo by Jeff Saucier)

Another possibility is that during the onset of the breeding season, what otherwise may be a prime feeding area a bit further north may still be frozen over.  After the breeding season, these food-rich areas are now available to any birds willing to make a side trip to the north, west, or east before finally going south for the winter.

A third possibility is that northern areas may have plenty of feeding areas, but not necessarily close to preferred habitat for nesting.  After breeding is over, birds only have themselves to worry about and their worries are likely quite simple: food, water, and avoid predators and mistakes.

Whatever the reasons for their nondirectional wanderings, these birds are welcomed by Maine’s enthusiastic birders.  Enjoy these sightings, for it won’t be long before the egrets and all other herons in the state steer their path directly southward.

A radiograph of a common loon showing a lead sinker (the brightest white object) in its gizzard. Photo courtesy of Avian Haven.

One of my not-so-glamorous duties as a wildlife biologist in our agency’s Bird Group is to collect dead loons and send them to the Tufts School of Veterinary Medicine’s Wildlife Clinic to be necropsied (a necropsy is an autopsy of a wild animal).  Dr. Mark Pokras and his students determine the cause of death as part of an ongoing study, and then let me know so I can inform the concerned citizen who originally notified me or a coworker of the dead loon.  I just finished cataloguing, bagging, and freezing 2 loon chicks and 5 adults.  With the help of Avian Haven, a wild bird rehabilitation facility in Freedom, we were able to get radiographs of a few adults – 2 individuals showed obvious lead sinkers in their gizzards.  These were both adults, most likely breeding adults, that were otherwise healthy.  A sad twist of fate presented them a lead sinker instead of an ordinary stone to add to the numerous stones already in their gizzard used for grinding food.  It doesn’t take much lead to cause lead poisoning, and death is only a few days away. 

Loons are not the only wildlife species susceptible to lead poisoning from discarded lead fishing tackle.  Any wildlife that eats fish or feeds off the bottom of wetlands, ponds, or lakes, is susceptible.  This of course includes great blue herons and many other colonial wading birds…thus the reason I am posting this topic on this blog.  

But, I do have some good news.  There is a program happening right now, right here in Maine that is offering FREE non-lead fishing tackle in exchange for YOUR lead tackle.  Read the news release below and find a participating Soil & Water Conservation District near you to help make a difference in our favorite fish-eaters’ lives!  Thank you.     

~~~~~~~~~ 

ANGLERS! 

Its time to swap out that old lead fishing tackle – for free!  

Announcing the Soil and Water Conservation District Lead Fishing Tackle Exchange Program 2010 

In partnership with the Maine Outdoor Heritage Fund 

Why not lead?  

• Lead has been known for centuries to be toxic – to humans and wildlife alike.

• Angling and other outdoor sports deposit thousands of tons of lead into the environment each year. 

• Lead ingestion is a death sentence for Maine’s loons, other water birds, and even the raptors, such as bald eagles, that may feed on these water birds.  Water birds ingest lead when foraging on lake bottoms for the gravel they require or from feeding on fish attached to lead fishing gear.  As the lead sinker or jig is exposed to the pebbles in the gizzard and acids of the stomach, lead enters the bird’s system and slowly poisons the bird. 

• Children are particularly susceptible to lead absorption.  Children handling lead sinkers and jigs are at risk of lead poisoning.

What are the alternatives? 

There are many non-toxic alternatives to lead fishing tackle, including those made of natural rocks, tin, steel, bismuth, ceramic and more.  Many retail stores carry these alternatives and still more would be carried if the public demand for these products increased.  

Now anglers in 8 counties (see District contacts below) can clean the toxic tackle out of their boxes and get replacement non-toxic tackle for free!  Program begins in May and will continue while supplies last.  Contact your District office to learn more about the program or simply stop by with your tackle box.  The program isn’t necessarily a one-for-one exchange, but there will be a great variety of non-toxic tackle to try, and no one will go home empty-handed!  What better time than right now to spring clean your tackle box, making fishing safer for you, your children, and Maine’s wildlife?  

Together, we can prevent lead poisoning.  Your choices can save lives. 

District Contacts: 

Remains found beneath heron nests. Clockwise from top left: egg shells and membranes, crayfish claw and fish backbone, fused rear vertebrae and pelvis (from 3 different aged herons), heron feathers, heron skull and mandible, leg and wing bones.

Did you know that you can learn a lot by what is on the ground at the base of a heron’s nest tree?  A heron nest is only so big, so there’s no room for food remains and other forms of heron “trash”.  Herons simply just pitch it all over the edge.  Out of sight, out of mind, I guess.  Light blue eggshells with some membranes in tact indicate a successful hatch; but you may also find remains of young herons that met their premature demise by falling to the ground.  Adult feathers that were molted are often found.  You might find out that crayfish is a favorite food of the family above.  This disposal area for the herons nesting above can really be a treasure trove to a researcher trying to find out how dam removal affects the birds that use a river.

Erynn Call is a PhD student at the University of Maine in Orono.  Her research is trying to answer a fairly complex question:  How will the Penobscot River Restoration Project impact the river bird community?  For those of you unfamiliar with the restoration project, it is aiming to restore 11 species of sea-run fish to the Penobscot River, while maintaining hydropower energy production.  In order to accomplish this, the Penobscot River Restoration Trust has purchased and will remove the two lowermost dams on the Penobscot River, Veazie and Great Works, and has purchased and will decommission a third dam, Howland Dam, where a fish bypass will be constructed.

So what does a heron’s trash have to do with it?  In Erynn’s words:

“Understanding the feeding and habitat relationships of various species is a key to unraveling ecosystem function and thus is critically important in discerning responses to human impacts…Many bird species rely on the river system and can be linked to the river food web as omnivores, insectivores, and of course, piscivores (fish eaters)…This study examines community dynamics of riverine birds and their interactions with dams and river habitat variation…The ultimate goal…is to quantify how bird assemblages respond to…dam removal and the subsequent restoration of spawning diadramous fishes.”

Among several objectives of the study, Erynn aims to evaluate the relative importance of marine-derived nutrients to riverine birds such as the great blue heron, bald eagle, osprey, and belted kingfisher.  Bird samples (blood, feathers, bones) and bird prey items will be collected within inland and coastal areas in Maine with particular emphasis on the Penobscot River ranging from East Millinocket to Bucksport.  Stable isotope analysis of the collected materials will reveal the diet and habitat of the animals at the time of their growth.  Results will provide an important baseline to examine how the diets of great blue herons and other fish-eating birds shift in response to the restoration of sea-run fish to the Penobscot River.

For this reason, Heron Observation Network volunteers have been asked to visit the colonies they’ve adopted sometime this fall to collect any “heron trash” they can find beneath the nest trees.  Unfortunately, most of Maine’s great blue heron colonies are located within wetlands where the nest trees are surrounded by open water, not allowing for materials to collect at the base of the tree.  Thus materials will only be collected from colonies in uplands or from those that contain individual nest tress that are on somewhat dry ground.  Samples will be placed in Ziploc bags labeled with the colony number and location and shipped to myself or Erynn Call for eventual analysis.  I expect that as sea-run fish return to the river, their remains will also be seen in higher abundance beneath great blue heron nests.  We’ll just have to wait and see.

In the meantime, check back here for updates on this aspect of Erynn’s research, or learn more about the Penobscot River Restoration Project.

The collection protocol for HERON volunteers has been posted to the File Cabinet.