Friday, September 13, 2013

Purple Martins: One Man's Journey

This is a personal story about my dad and Purple Martins. There are countless wildlife conservation projects going on all around the world - efforts underway to save critically endangered species from extinction and preserve the ecosystems in which they live. This work usually falls on scientific experts, but anyone who loves nature can become its steward. I think my dad will agree that this journey asks for patience, commitment, a certain toughness and yes, love, but it gives back so much as you experience the natural world opening up before you, allowing a glimpse of its myriad secrets.

My dad is retired and one of his many hobbies, along with gardening, camping and HAM radio, is caring for and photographing many species of wild birds that call his farm home. Here he is, weeding rows of flowering potatoes in his garden, below. All unattributed photos are courtesy of my dad.


Every summer I visit, I see new and different bird feeders hung up on shepherd hooks somewhere visible from a window, and they are indeed a beautiful sight as the clientele varies season to season. Caring for "his" birds is one of many ways in which he is a steward of our fascinating planet. He is an excellent role model for me and he is a perfect subject for this article in the Caring for Earth series.

About The Purple Martin

This species of North American swallow, Progne subis, gets its common name from the male's iridescent purple sheen over its entirely black coat (below right).

JJ Cadiz, Cajay;Wikepedi
Purple Martins, like all swallows, are given away by their slim sharp beaks, forked tails and long pointed wings - all of which are perfect adaptations for hunting insects on the wing - and like all swallows, Purple Martins are stunning aerial acrobats, making them endlessly fascinating to watch.

Like most birds, the female though not as flamboyant, has her own reserved elegance, below left.

Shanthanu Bhardwaj;Wikipedia








These birds, though not threatened at present, suffered a severe population crash a number of decades ago when European starlings were released and spread throughout North America, competing for the Martin's limited supply of natural nest cavities. By the 1980's, Purple Martins had all but vanished from many places in North America, but they are recovering thanks to human intervention, and are now listed as Least Concern under the IUCN Red List of Threatened Species.

There are three subspecies of Purple Martin, those which breed in Eastern North America and Eastern Mexico, nesting in old woodpecker holes, those breeding in the deserts in Arizona, western Mexico and the Baja peninsula, where they often use holes in saguaro cacti to make their nests, and those that breed on the Pacific coast of the United States as well as the Rocky Mountains. Dad's Purple Martins may belong to either the Eastern or Pacific subspecies. The Pacific subspecies (Progne subis arboricola) is currently Blue-listed in British Columbia, meaning that it is a species at risk or vulnerable but not threatened. All subspecies migrate to the Amazon basin in Brazil to winter.

Purple Martins are very social birds. They prefer to nest in colonies, and you will hear them chattering to each other night and day. Here is a sample:



Humans have significantly helped the Purple Martin population by supplying them with nesting cavities, ranging from a collection of hollowed out gourds to elaborate wooden condos. The Purple Martin Conservation Association estimates that over one million North Americans have put up Purple Martin homes.

Starlings and house sparrows also love these readymade houses and they may discover them first, staking their claim and driving the less aggressive Purple Martin away, but groups of older Purple Martins especially those that have previously nested in the site may gang up on these species and drive them back out. Today, Purple Martin populations are spotty but generally holding their own across North America, reflecting the availability of an increasing number of manmade nesting sites and improving management practices. The Edmonton area of Alberta marks the approximate northern limit of its range, which depends mostly on food availability. Here, birds arrive around mid-May when average temperatures of at least 10°C allow some insects to be active and available as food. In Alberta, Purple Martins breed in June and chicks hatch in July when insects are most plentiful, a much later breeding season than that of California, for example. By mid-August, hatchling Purple Martins have fledged (learned to fly) and soon afterward the birds begin their long migration south.

Purple Martins fly approximately 7000 kilometres between Brazil and Central Alberta. Recent research conducted in Ontario suggests that, although there is a connection between weather patterns in Brazil and Canada, this route is too long for the birds to predict when spring will be in full swing and insects will be plentiful so far away. This means that they start their migration north at about the same time every year and they must survive, often significant, variations in temperature and insect availability, especially at the northern extremes of their range. As climate change further increases weather unpredictability, Purple Martin's may flourish one year but perish the next, adding stress to already stressed populations. Building shelters for the birds goes a long way toward supporting them through climate change.

Setting Up for Purple Martins: My Dad's Story

Last fall, my dad noticed some gorgeous new Purple Martin condos showing up in the nearby village of Edberg. These condos were designed by Bob Buskas in 2000, a design called the North Star House. They can be purchased through his website, Northern Sky's Purple Martin Colony. He also sells a 14 page binder style booklet, complete with cutting instructions, photos and step by step assembly instructions for the house, as well as the pole and winch assembly if you would like to build one yourself.

As Dad waited for the condo he ordered to be built, he researched Purple Martin care online. Research either online or through books is absolutely essential to successfully establishing and maintaining a healthy Purple Martin colony. A well-built Purple Martin condominium is not only a fairly expensive investment, but managing a colony requires time and effort that you don't want to waste. Here are some excellent websites to research (where applicable I've cued them to the Purple Martin):

Purple Martin Conservation Association
NestWatch
All About Birds
Ontario Purple Martin Association
Western Purple Martin Foundation (in British Columbia)
Chuck's Purple Martin Page
Northern Sky's Purple Martin Colony (in Alberta)

He was very excited when he picked up his new condo in late winter, and thanks to an early thermal blanket of snow last fall, he was able to drill a deep posthole to secure the condo in place well before any birds arrived, shown below.


This open location is ideal. Purple Martin houses are best located at least 18 metres away from any trees or buildings and about 30 metres from human housing or activity. These distances are important because it provides the martins with enough flight area while being close enough to humans to discourage most predators. For this reason, Purple Martin houses are impractical for many city and town dwellers with smaller yards, such as myself, but acreages, farms, golf courses and large parks are well suited to a Purple Martin colony. I suspect it may be possible to arrange to install and manage a Purple Martin colony on school grounds, hospital grounds or a golf course, and this has been done, as you will see later on. Dad's condo is set about 5 metres from the ground. This height reduces access to any ground predators while remaining accessible to regular inspection. A winch system or a telescoping pole is essential, as it should be monitored to immediately remove any house sparrow or starling nests and you will know right away if snakes, raccoons, owls, Merlins, hawks or parasites are harming your colony.

An additional owl/hawk guard can be made or purchased. Purple Martins are noisy at night so owls, for example, can easily discover them. An owl will often hook one clawed foot in an entrance and beat against the condo with its wings to drive out the Purple Martins inside. It will then capture one as it attempts to leave. The owl will return back night after night until the entire colony is decimated. Owls are native protected birds, so you cannot harm them in any way.

The size and shape of the entrances to the house is very important. Ontario's site offers diagrams of various starling resistant styles and a guide to dimensions. Dad's condo entrances are those suggested by the Purple Martin Conservation Association: 3-inch by 13/16-inch half crescents with the flat bottom just 1/2 inch above each perch. The height of the entrance is especially critical - just a hair higher and starlings will be able to squeeze their way inside.

This condo is made of wood and painted white on the outside. White not only reflects the Sun's heat so that chicks won't suffer as much heat stress on hot days but it also makes dark entrance holes easier for the birds to see. There is much anecdotal evidence that a white condo or gourd collection enhances colonization success. Wood (cedar, pine, cypress or redwood) is the preferred construction material because it offers insulation from heat and cold and it is easy to work with.

Dad's condo comes with 12 removable individual nesting compartments - ideal for cleaning and monitoring. Each compartment is large (about 18cm wide and 30 cm long). Compartments as small as 15 cm by 15 cm are acceptable but larger ones offer the chicks more room to move as well as better protection from the weather and predators. An adult Purple Martin is about 20 cm long so this size also gives the parent some room to maneuver as it broods as well. Here, they are primed brown with low VOC paint (below left) but they can certainly be left unpainted.




In order to maximize his chances of attracting Purple Martin passersby, Dad chose to give his nesting boxes a comfortable lived-in look and feel. First, he mixed a thin paste of dirt and water and painted the insides of the boxes, a process called mudding the nests, shown below right.








He let them dry thoroughly in the Sun and then made a pre-fab nest out of straw for each box, below left.

A similar procedure is recommended by the Ontario Purple Martin Association. Straw, hay, cedar chips or pine needles on the floor of each unit all work to provide a welcoming home. Young year-old birds are newbies at nest building, so these move-in-ready homes will be irresistible to them.

The Ontario Association goes even further by suggesting that you can dab a little white non-toxic craft paint in a strip about 5 to 10 cm long up an inner wall using a Q-tip ®. When an interested Purple Martin looks in and sees the "poo," it will think that baby martins were raised there, a technique similar to staging an empty house with furniture for a quicker sale.

These nesting boxes are now ready to be installed (below right) and the condo will be ready for Purple Martins.

Several sites suggest that you prepare your nests and then plug up the entrances until the martins are due to arrive in your area. This practice discourages starlings and house sparrows from setting up house before your martins arrive.

Purple Martins tend to re-use the same nesting sites year over year so you are most likely to attract sub adults. These are last year's young and this is their first time setting up a household. The Purple Martin Conservation Association offers a handy arrival time map of North America with instructions on how to use it to the right of the page. Dad's farm is located in mid-Alberta so his arrival time is around May 1st. This is the time when the first experienced adults start arriving. You can open your homes on this date but it is important to know that sub adults tend to arrive 4 weeks after the first adults do, so if you open on May 1st, you will need to keep a close guard for competing birds as it may remain empty for an entire month. Several experts suggest that you don't open until the sub adults are expected, around the end of May for Dad's area. Throughout North America, keep your home open until the end of June because Martin migration is long and drawn out. You may get stragglers this late in this season.

As Dad waited and monitored his condo, he set up a journal to record his observations, an excellent practice in addition to his photographic record that will help with any troubleshooting down the road.

And The Fun Begins!

Soon he saw his first Purple Martins (YES!), a male and a female, below.


Later, he saw three Purple Martins and a single sparrow, which was likely driven off by them soon after the photo, below, was taken. As an established group, the martins can usually drive away single house sparrows that come along looking for nests.


If a Purple Martin colony is not yet well established, both house sparrows and starlings will likely drive away the martins by running them off continuously. If any eggs or chicks are present they will go from nest to nest killing them and then stake a claim for themselves. If a parent martin is brooding, starlings in particular will kill the parent as well as the chicks by pecking them to death.

Know Your Enemy

The common starling (Sturnus vulgaris) was introduced to North America in 1890. An original 60 birds has grown to a population of around 150 million, extending from mid-Canada to Central America. In addition to Purple Martins, they compete with chickadees, nuthatches, woodpeckers and other swallows. It is one of the 100 most globally invasive species as listed by the International Union for Conservation of Nature. It is a beautiful bird, nonetheless (below left).

Philip Heron;Wikipedia


Your local common starlings might not look exactly like this, however, as there are numerous subspecies, each of which varies slightly in size and colour. Males and females look alike.




The house (or European) sparrow (Passer domesticus) is both widespread and abundant, and like the starling, it was introduced to North America from Europe. Male plumage varies between breeding (below left) and non-breeding (below right) season.


(Non-Breeding) Passer_domesticus_on_rose.jpg:                
 PewuCom;Wikipedia


               (Breeding) (Passer_domesticus_male_(1).jpg:
 Lip Kee Yap;Wikipedia












The adult female looks like this:

DAVID ILIFF. License: CC-BY-SA 3.0 (Wikipedia)
House sparrows will build a tightly woven nest with a small opening inside a condo compartment, preventing Purple Martin access (native sparrows pose no problem as they do not nest in cavities). House sparrows will also sneak into unguarded Purple Martin nests to destroy eggs or kill chicks, and then take over the nest for themselves. Sparrow eggs are deeply speckled grey and white and can easily be distinguished from the Purple Martin's pure white eggs.

While sparrows are significant pests to Purple Martins, starlings are true killing machines. Their beaks are dagger-like and much stronger than a Purple Martin's beak and they are far more muscular. A starling nest will tend to have a much deeper bowl than a Purple Martin's nest and the starling will fill the nest with much more material. Starling eggs are robin-egg size and powder blue, while Purple Martin eggs are a bit smaller and pure white. Removing any starling nests is essential but it can be an endless job as starlings and house sparrows, in particular, are stubborn and will often remake the nest every single day during nesting season. Because both starlings and house sparrows are non-native, and in absolutely no danger of extinction, there are no federal laws protecting them and it is legal to kill them by trapping and euthanasia or shooting if permitted. Trapping and relocating does not work, as those birds will quickly return to the same site.

While Purple Martins produce only one brood per year, starlings often produce two, and sometimes three, using the same nest over and over. House sparrows brood twice per year and sometimes will produce three or even four broods if the season is long and warm. Clutches of all three species are of similar number, so this is another way in which house sparrows and starlings outcompete Purple Martins.

Chuck's Purple Martin Page offers lots of sensible advice along with lots of photos to help you deal with these bird pests. Killing starlings and house sparrows sounds harsh, considering that you are in the business of bird stewardship not destruction, but you should keep in mind that Purple Martins are native to North America and are sustained against more aggressive non-native birds almost entirely, particularly in the east, by man-made nesting sites and ongoing management. In the following 6-minute video, Mark Howery from the Oklahoma Department of Wildlife Conservation joins Oklahoma Gardening host Kim Toscano to discuss the management of purple martin houses:



In this video, he shows how to recognize a house sparrow nest and remove it.

Babies!

Several mating pairs soon moved into Dad's condo, below.


By mid June Dad observed fresh green leaves in one of his nests. The female will usually add a finishing touch such as fresh leaves to her nest, which is often a sign that eggs will soon be laid. The nest is shown below.




As expected, egg laying soon followed. The female will usually lay between three and six eggs, which will take about 16 days to hatch. If you look closely at the photo below, you can see that a male Purple Martin has a dragonfly in its beak. A chick has probably hatched and he is bringing food to it.


Purple Martins feed on flying insects, catching them on the wing. The female does most of the incubating while the male relieves her for short periods as she feeds.

Dad was immensely gratified by his next discovery (below right). The first chick of his new condo hatches!













Followed by two more chicks the next day (below):


Inspect Frequently and Thoroughly

Chuck's site mentions something to keep in mind as you inspect your hatching nests. Even if you inspect during the day you may open a tray and discover the mother bird there, brooding her eggs. Don't panic; as you visit your condo over and over, your Purple Martins will get to know you and trust you. He mentions that he sometimes has to gently lever mom up for a moment using a clean Popsicle stick in order to inspect all the eggs and chicks underneath her. You may have heard that if you touch the eggs or even the nest, the mother will abandon her chicks. This is not true. All the Purple Martin websites I researched strongly encourage regular and thorough nest inspections. You can put up a condo and let nature take its course, but your success may be greatly reduced. You are most likely to have bought an expensive home for starlings to bread in and thus harm the Purple Martin population rather than help it. Or, your condo may become infested with mites, fleas, blackflies or blowflies, which can destroy an entire colony of Purple Martins. His site gives you clear instructions (look at left menu bar) on how to do nest checks and what to look for.

Supplemental Feeding May Be An Option

As I mentioned earlier, Purple Martins face an extra challenge at their northern limit here in Alberta. Insects will not fly during spring cold snaps and a severe cold spell can starve a whole colony of nestlings. Climate change means that weather patterns may continue to grow more unpredictable in the future, so supplemental feeding may be an excellent way to help keep your colony thriving. Although these birds are aerial insect-eaters, they will also enjoy mealworms, grasshoppers, crushed oyster shells and even scrambled egg! Bob Buskas, author of the  Northern Sky's Purple Martin Colony website, shows you how to set up your own "Oyster Bar" for your Purple Martins.

Managing Purple Martin Parasites

Most online sources suggest that parasite infestations should be dealt with, as they can reduce the overall Purple Martin chick survival rate by up to half. While it is true that Purple Martins co-evolved with various parasites and it is certainly an option to let nature take its course, many experts suggest that they be dealt with in order to maximize the success of your efforts toward maintaining the population, especially if you notice a particularly heavy infestation. Purplemartin.org has an excellent article, with photos, called "What's Bugging Your Birds: An Introduction to the Ectoparasites of Purple Martins."

Blowflies are most common in the northern part of the Purple Martin range. A heavy infestation of blowfly larvae will suck the blood from a chick until it dies. These are quite easy to spot and there is a vivid photo of a Purple Martin chick covered with them if you click the link above. Another common parasite to watch out for is the nest mite. These black 1-mm long mites (there are two species in North America( may reach huge numbers and you will see them crawling all over the nest and chicks. They, too, suck the blood of chicks, weakening them until they die. You may also find martin fleas and their larvae as well as other pests. The parent birds may abandon the nest and chicks if it is heavily infested.

In the past, pesticides, particularly Sevin ®,  have been used and some sites still suggest this option as it has been proven to be very effective, but more and more experts are turning away from this tactic. Purplemartin.org has interesting pro- and anti-Sevin ® articles for you to check out.

Pesticides may damage the birds in the long-term as reproductive and other long-term health effects are largely unknown. Carbaryl, the active ingredient in Sevin ®  is extremely toxic to humans and it is probably not in your interest to be in close proximity to it either. Growing knowledge about the overall ecological damage caused by pesticide use, such as a possible link to honeybee colony collapse disorder for example, make this option less and less attractive to many Purple Martin landlords. Another effective way to control infestations is to do a nest change. The basic procedure is shown in the 5-minute video below:



An infested nest can be removed and replaced with a fresh bed of dried grass clippings, dried pine needles or wood shavings. Most of the mites or larvae will be removed with the nest. This should first be done only when the chicks are about 10 - 14 days old, according to Purple Martin expert, Bob Buskas. By this age, the nestlings are beginning to develop their adult feathers and they are vocal, begging for food. Although some websites suggest that doing a nest change at a younger age will not make the mother abandon them, Bob tells us that waiting until the nestlings are old enough to beg ensures that this won't happen, and as usually only a single nest change, when confronted with a heavy infestation, is sufficient to reduce the pests to a manageable level, this later approach is the safest way to go. Simply remove each chick one at a time, removing any parasites on it, to a clean empty 5-gallon pail or an extra clean compartment lined with wood chips or dry grass clippings or a readymade nest while you discard their old nest.

Watching Purple Martins Grow

Another nest of six chicks, just hatched, is shown below, followed by the same chicks five days later.


What a remarkable change! They've doubled in size and their feathers are just starting to come in.

You might also want to monitor your nesting birds even more closely with either a time-lapse camera or set up for live video streaming. A word of caution here: All About Nestcams website (first link) warns you not to become obsessed or freaked out by what you might see. You don't want to become a micromanager of your birds.

Regular nest checks should continue about once every four or five days until the oldest chicks are about 22 days old. At this point they are beginning to fledge, or learn to fly. You don't want to risk startling one into jumping out of the nest before it can fly. Regular walk-unders, however, are encouraged and you might catch a glimpse of chicks taking to wing for the first time! Below, Dad got a photo of two hungry chicks poking out of their compartment waiting for a parent to bring home lunch. So cute!


By mid-August all of Dad's Purple Martins had left and the condo remained empty until several days later when he noticed a new group of Purple Martins using his condo as temporary lodging. These birds may be fledglings from elsewhere looking for next year's housing. He knew these martins were not his because as he walked under the condo and whistled these birds flew away, frightened. His birds, on the other hand, often poked their heads out to see him and sometimes greeted him with chirps.

Condo Aftercare

Late August is the time to clean out each compartment. Remove each nest and scrub the compartment with 10% bleach solution (1 part bleach to 9 parts water). This practice will go along way toward keeping the homes disease and parasite free. Rinse and air-dry thoroughly and do any repairs that are needed. Then either cover up the condo to protect it from weather and seal it from other birds and animals, or if it is removable, remove it to dry storage for the winter.

If you live in Alberta and would like to start your own Purple Martin colony, I recommend a visit to Bob Buskas's website called Northern Sky's Purple Martin Colony. Over many years Bob has established two large colonies, which you can visit - one at the Country Nine golf course just north of Bashaw and the other located southeast of Wetaskiwin on his farm. You can also read several excellent articles in which he shares his extensive experience on how to attract and manage your own Purple Martins, with information specific to Alberta. He also builds two styles of Purple Martin homes as well as sparrow and starling traps for purchase, and he welcomes you to visit him, share stories and learn. All the contact information is on the website.

Dad did an awesome job attracting and caring for Purple Martins! I thank him for sharing his fascinating adventure with me (and you!), one that for him is just beginning.

No comments:

Post a Comment