Archive for the ‘predators’ Category

Screech Owls Need a Hand

Thursday, November 3rd, 2011

As a proponent of all native cavity nesting birds, I again was reminded of the housing shortage when the floor to the much sought screech owlsafter Flicker nest box fell out. After several seasons of hard use, interest by Woodpeckers, Greater Crested Flycatchers, Screech Owls and most recently, Horned owl attacks, 2 new nest boxes will be going up this weekend. I will be adding some experimental Owl Guards to keep the larger Barred/Horned Owls from killing their smaller “Screech-y” cousins.The Screech Owls seem to get caught by the Repeating nest box trap once a season. Even though the trap is placed lower to the ground than what Owls are said to like, my theory is that they are always desperate for nest sites and will investigate any cavity.

As a few cool days have reminded me of approaching winter and the news shows snow storms already battering some States, I welcome my yearly Eastern Phoebe friends that I have seen.

In “Honor” of National Feral Cat Day…really?

Sunday, October 16th, 2011

As a cat lover and even former cat owner (indoors, thank you) I feel perfectly at peace talking about National Feral Cat Day and re-posting one of our former posts on Feral cats and their impact to bird and native wildlife population. I am saddened thinking about the millions of feral domestic animals (yes, cats) that are thrown out by humans. And again my thoughts go to the HUNDREDS OF MILLIONS of birds and other native wildlife who’s lives are not deemed as valuable by the people that enable these cat colonies. Read on…
Did you hear that? It is the sound of my soap box being pulled out of the closet and dusted off. I have been wanting to write about a very big pet peeve of mine for some time…so now that my birds are gone, here goes.

As a birder, it goes without saying that I am a conservationist. As a purple martin landlord, that just adds fuel to the fire and makes me even more pig headed when it comes to the house cat being outdoors. First off a few facts MUST be cleared up.

Fact #1 Cats are domesticated animals-not wild. Many people consider letting their cat room outside as an extension of the cats native environment. They consider it cruel to keep cats indoors. When actually the opposite is true. Cats were domesticated some 4,000 (four THOUSAND) years ago. They do not occur naturally anywhere. They have only been in North America since European Settlers arrived.

Fact#2 Cats hunt and kill whether or not they are hungry. Studies show that well fed cats actually kill MORE than feral cats. In other words they hunt for pleasure. The portion of the cats brain that is used to hunt is not the same part of the brain that registers hunger. Thus a cat will hunt even if it just ate a huge bowl of food. They hunt to kill, not necessarily to eat. Also neutering and spaying have no impact on a cats desire to hunt.

Fact#3 Studies have shown that Bells do not keep cats from killing. On the contrary bells may actually make cats more successful at hunting. Besides the fact that a bird does not necessarily associate the sound of a bell with danger, bells teach a cat how to hunt even more efficiently. The cat will learn how to move silently. And bells are of no help when a nest full of helpless nestlings is being stalked. Consider this product called the CatBib. Their website has a study that was conducted that shows an 81% decrease in the amount of BIRD KILLS! That is impressive. Unquestionably more effective than a bell this device allows the cat free movement, is soft, flexible and lightweight yet restricts a cats ability to stalk prey.

Fact#4 Cats kill HUNDREDS of MILLIONS of birds nationwide per year. That is no trivial number even though it is a low ball number. According to a post on Windstar.org that estimates over a BILLION birds are killed each year in the US alone. And looking at the math, that number may be conservative as well.

Follows is a sobering quote from www.Windstar.org :
The American Veterinary Medical Association estimate in 2007 there were 81,721,000 pet cats in the U.S.
According to Cat Fanciers, 43% of cat owners allow their pets to roam outside, that gives us: 35.1 million outdoor pet cats in the U.S. Add the number of feral and stray cats. numbers published by feral cat advocacy groups say there are between 60 to 100 million cats. Lets just take half that number say 81 million.

So that’s 81.7 million + 35.1 million = 116.8 million outdoor cats. More realistic might be a range of 95.1 to 135.1 million (based on possible feral range). But for arguments sake, lets just stick with 116.8 million cats for now.

How many birds killed by cats? According to a study in Michigan by Lepczyk et al, outdoor pet cats across an urban to rural gradient killed an average of .683 birds each week during the breeding season. If you can extrapolate that across the full year, that would be an average of 35.5 birds killed by each cat/each year. If you can use that figure for all outdoor cats, you get a calculation of 4.1 billion birds killed each year.

But maybe cats don’t kill birds at the same rate all year long, or at the same rate everywhere that they do in Michigan. But lets presume that the only kill birds during the breeding season (22 weeks in MI), that would still be 1.76 billion birds killed per year.

Another study in San Diego found each cat to kill an average of 15 birds per year (and 41 other small animals). If you multiply this number by the number of outdoor cats you get 1.75 billion birds killed per year. And that’s just in the U.S. and doesn’t take into account our migratory birds killed by cats in Canada or Latin America.”

Fact#5 Cats are responsible for the EXTINCTION of 33 bird species since the 1600′s. That is more bird species than any other cause, except habitat destruction. Currently there are dozens of seriously threatened birds that are still experiencing high levels of predation due to cats. Ground nesting birds, such as the Piping Plover, Least Tern and California Tern are even more at risk and several monitored nesting sites have been abandoned by these birds due to cats.


So you know all this data and you still feel it necessary to let your cat out. If that is the case, you are placing more value on your cats experiences outside than the animals that it will kill in its time outdoors.

 

If you think your cats rodent killing is a positive, think about this. Each mouse that a cat kills is decreasing the available food supply for native hawks, owls, snakes and other predator species.

If you believe TNR (Trap Neuter Release) programs work to decreasing the problems caused by feral cats, I urge you to visit TNR Reality Check. This site offers an eye opening reason why TNR programs are a huge dis-service to the community, environment and our birds. Most importantly it show why these TNR programs do NOT work.

So if bells don’t work, what can be done. The American Bird Conservancy runs a program called “Cats Indoors!” which I am a big supporter of. (I am available to give PowerPoint presentations of the “Cats Indoors!” programs to groups, BTW)

Don’t have a cat and want to make a difference? Re-Tweet this post and help inform birders and cat lovers alike.


Sources:

 

Coleman, Temple and Craven (1997). Facts on cats and wildlife: a conservation dilemma., USDA cooperative extension, University of Wisconsin. http://www.cnr.vt.edu/extension/fiw/wildlife/damage/Cats.pdf

TNR Reality Check

Winter, Linda and Wallace, George (2006) Impacts of Feral and Free-Ranging Cats on Bird Species of Conservation Concern

How to Make Snake Netting to Protect Your Martins

Sunday, October 9th, 2011

Krueger Snake NetBluebird trails, Tree swallow boxes and purple martin landlords can all benefit from using snake netting (actually bird netting) on your poles. Snakes can climb up any pole and can even thwart many predator guards. Since no predator guard is 100% fool proof, this quick and easy tip can further decrease the chances of one of these critters from slinking their way up your martin pole.

Bird netting can be found at just about any garden center, home improvement center and is used to keep birds from eating the fruit and veggies in your garden. It can be found in either rolls or flat packaging, and comes in several sizes. We recommend using 2 sizes to protect against larger and smaller snakes. 1/4 inch and 1/2 inch.

European Starling and Bird Netting

The exact way to attach the netting to your poles is unimportant. The netting needs to be held out and away from the pole to both prevent ground predators from using the net to circumvent any other predator guards in place (such as a stovepipe type)  and to make the snake go through the net rather than up and around it. Thus the exact way to layer the netting is  a debatable issue. Many different techniques have been used successfully. The main idea is for it to be above your predator guard to serve as a last “hail Mary” of protection. The netting should be full and hang loosely. Think of a big fluffy skirt under your housing.

The image of the Krueger Snake Net above will take you to the website of Audubon-omaha.org page on how to make your own snake netting.

Nest Checks On Hold

Wednesday, May 11th, 2011

When do you stop doing nest checks? When the nestlings reach about 23 days old. Some folks say 20 days old, but that seems overly cautious to me. All nest checks are on hold as their are tons of nests ready to fledge any day now. The nests that have fledged (about 8 of them so far) are creating much excitement as they peek into compartments and try to steal food from smaller younger nestlings.

A hawk made a late pass right before dark tonight and I am not sure if he was successful or not. The entire colony flew up in masse and with such an uproar of alarm calls that I am sure some bird was taken. Those early morning and late evening attacks are often quite successful. I will have to stay out later tomorrow and see.

I am not sure when the low hanging gourds are due to fledge soon. It will be interesting to see how the youngsters take to the air without having the advantage of height to get them airborne.

Where Your Purple Martins Went

Sunday, June 20th, 2010

As the purple martin season for 2010 winds down in the Southern states and hope for wannabe landlord dwindles, I have heard some folks wondering where their purple martins went. Some established colonies have even reported the complete failure of their colonies to arrive at all. In this article by Cynthia Porter from the Winona Post she describes some landlords experience with colony loss. There was some speculation about “where the martins have gone” and I hope to add some clarity to that issue.

The article mentions specifically that the martins were, “stalled in April due to low pressure systems in the south. That delay seems to have upset normal migration patterns in which birds like purple martins send scout males first, followed later by females.”

I thought that I just had to clarify this statement that seems to speak to the age old (and false) myth that purple martins will send out “scouts” ahead of the rest of the colony. Purple martins experience a staggered molt in South America and  older birds will complete molting before younger birds do. The phenomenon known as “scouts” is actually just older more experienced birds rushing “home” to secure nesting prime nesting spots. Now that we have that straightened out…

As far as why YOUR purple martins never arrived; there is only really one reason.

The colony experienced losses of adult birds, nestlings and fledglings due to predation, weather extremes (cold or drought) greater than the rate of reproduction.

Here is how that can happen:

1. Prolonged Cold Spring Snaps

2.Extended Dry Weather / Drought

3. Predation

Let me go into detail on these:

In cold weather (temps of 40 degrees F or below) aerial insects are not available and starvation will occur within days. Record Low temps for record breaking extended periods of time, made foraging for food impossible for many purple martins. So birds that may have arrived early, didn’t survive this year. Purple Martin landlords often report of “early arrivers” braving intense spring cold snaps for days and even with poor weather forecast, martins will often times continue their journey Northward and remain at their colony site. Many landlords last year and this year reported huge losses of ASY (adult) purple martins from cold snaps such as these.

Droughts were widespread and severe in many areas in 2008 even more so in 2009. Reduced rain results in reduced amounts of aerial insects thus reducing available food supply. Large losses were reported last year of thousands of dead nestlings that starved to death. According to Louise Chambers of the Purple Martin Conservation Association, “.We don’t know if adults will return after total nesting failure” so even though “many landlords are reporting a very good season this year” it could be that those adults returned or their sites attracted new adults.

The most important factor and the one WE CAN DO SOMETHING ABOUT, is predation. Most predation goes undiscovered. Without safety precautions, such as predator guards in place, raccoons and snakes can easily climb ANY martin pole and go from martin nest to martin house for an easy meal. A colony can be decimated within days. Once a gang of raccoons finds the tasty treats (your birds) at the top of your purple martin pole, it will climb every pole in the neighborhood. And believe me, I have seen it Raccoons DO eat birds! Last year at our local roost, I witnessed raccoons dining at their leisure on so many purple martins that their body parts littered the ground like confetti. You can read the post here: Davie Fla Roost.

One of the reasons why the Purple Martin Conservation Association recommends nest checks is to discover problems early. By discovering problems such as nest predation, you can monitor the health and growth of your colony. Many landlords that report complete colony abandonment have in fact been suffering chronic losses and/or predation. The ultimate failure of many colonies could have been avoided by careful observation and having predator protection installed.

So to conclude, if you don’t observe your martins and perform nest checks, your colony may have suffered losses of adults from cold weather, losses of nestlings due to dry weather and, if unprotected, losses from ground predators as well. Then that is why you had no martins return at all.

If you are interested in reading more about raccoons and the threat they pose, try this article titled, “Raccoons in our Midst”.

If you want to know what other threats there are to your colony check out this surprisingly long list, “Threats.”

©2010 PurpleMartinArt.com / S.Halpin

Purple Martin Season Is Over for 2010

Thursday, June 17th, 2010

SY maleIt’s official, the last of the nests have fledged and all the babies have taken to the air. A hawk was making daily visits and though I am sure (s)he got at least 2 fledglings, I am sure more fell victim. I was unable to get a good look so I am hoping it was the resident Red Shouldered Hawk, a slower and larger hawk that poses a formidable threat but less so than the smaller faster Coopers Hawk that are common in South Florida also.

The Red Shouldered hawks nest close by and protect this as their territory from other hawks. If that can be counted as protection…I am not too sure.

Night time is quiet and I am not sure if many martins are returning to the nests to roost at night. They may have moved on to a local assembly area or pre-migratory roost. The fact that I am talking about the roosts already almost sounds crazy! Can time have flown by so fast? I guess I will start planning another trip to the roost in Davie this year.  It has almost been exactly a year since I went to see it and video taped it. You can see it at my blog post titled Purple Martin Pre-Migratory Roost Spectacular. It is a great YouTube clip taken at the roost with swarms of purple martins.

The webcam will not be up again for the remainder of this year as the computer I had it running on is dead. I plan on replacing it as soon as I can and it will be up again next January. I promise.

©2010 PurpleMartinArt.com / S.Halpin

Still No Vacancies

Monday, May 10th, 2010

SY birds are still looking for homes as I have noticed several birds tonight trying, in vane to be let into a gourd. One continues to sleep on the porch of the Sunset Inn martin house and a couple flew off into the dark. A SY female tried in vane to get into about 5 gourds which was not received well. Fighting and pecking and bickering ensued. The poor girl was determined and I am not sure where she ended up.

Though some SY males have succeeded in winning over a handful of gourds, all but 2 of my 31 gourds have eggs or babies.

I drive by several know locations of vacant purple martin housing and see no evidence of martins and know that just some minor tweaking of the location of the house is all that stands in the way of quite a few folks getting martins. After 2 seasons now of mailing fliers to neighborhood wannabe landlords, I have only heard back from a handful.

In the meantime, I continue to turn away purple martins into the night. I could put up another rack next year but I would much rather show a few how to turn their empty martin houses into active colonies.

Other bird news brings 2 fledgling Mockingbirds fluttering about the yard, a family of Common Grackles that I am not sure where they are nesting and a recently fledged Red Tailed hawk being shown the gourd racks this morning by its mother. Sadly a pair of Greater Crested Flycatchers is nowhere to be seen after they started nesting in the recently vacated Screech Owl box. I believe a Horned Owl returned to the box as I found a large Owl feather clinging to the front of the nest box the same day the Flycatchers disappeared. Now to fashion Owl guards for that nest box.

Nesting is Beginning!

Tuesday, March 30th, 2010

Finally after many long weeks the purple martins are starting to go to the tree tops and pull at needles and bark. All compartments are taken by ASY males and though I have seen SY males I do not see any that have been able to steal away a compartment.

I am hanging a few old gourds on shepherds hooks and though these gourds are barely 4 1/2 feet off the ground, I am sure they will be taken. Every year I get a pair to take up residence in the shepherds hook gourd so this year I added 2 more. Hay, why not? If they are desperate enough to nest in some of the houses I see them in,. why not a shepherds hook. Of course I use a predator protector to keep raccoons and other creepy crawlies from getting an easy meal. This picture was last years ASY takers and they fledged 4 (if I remember) from this gourd. Every morning there is a few ASY males giving tours to interested ladies but at this point many are still playing musical gourds so I can’t tell if they are serious. But I will let you know.

Speaking of serious, the first egg of the 2010 season has been reported. On March 27 in the Orlando area. (Congrats James M!) Mine usually follow by several weeks.

Swallow-Tailed Kites Return!

Tuesday, March 16th, 2010

After a long absence, the Swallow-Tailed Kites have FINALLY returned. It seems they are much delayed but purple martin are about the only birds I KNOW for sure when they will return.

I think the forked tail is why I enjoy watching these birds so much. Any bird with the name of “swallow” is a favorite. Though I have seen these birds snatch a dove nestling out of a nest. So don’t get too close!

Switching Martins from Round Entrances to SREH

Tuesday, February 23rd, 2010

At times I believe that with the ever increasing pressure from European Starlings, it would be just a matter of time before purple martins become extinct! Luckily for us landlords Charles McEwen of Mocton, NB developed the SREH or Starling Resistant Entrance Hole. This development has single-handedly helped save more purple martins than we will ever be able to count.

The starling resistant Crescent entrance, which has given rise to nearly a dozen variations has virtually neutralized the threat of the invasive European Starling to our native songbirds. Many folks deal with the pressure and destruction caused by starlings entering their round holed colonies, rather than converting their entrances to SREH because of the apparent difficulties one can have in teaching your martins how to navigate such an odd looking entrance. Looking at the entrances it is no wonder, the shapes are downright strange and seem to defy logic. How would a bird get in? But trust me! They do!

types of srehAs I stated before there are many types of starling resistant entrance holes, some of which are protected by patents and copyrights. Some have even touted Starling Proof entrances, though in my opinion, it is a bit premature to stake that claim. You can read more about “starling proof” entrances HERE. There are also many opinions as to which SREH is better or more effective than the next. I have only tried a handful myself and even with SREH I continue to trap non native starlings at my colony.

Most of my 30+ compartments are Conley II (also called “The Clubhouse” entrance) and crescents. I have a gourd with a modified Excluder and one with an Excluder II also. ALL fill with martins.
I must admit that at first I had some issues switching them over but eventually they got the hang of it.
If your colony is established, that is they are bonded to your site and have nested there before, they should figure it out pretty quickly. You may witness the SREH Shimmy (as I call it) which is often mistaken for the martins “not fitting” into the new entrance hole. Do not fret, these designs have been designed and tested with many thousands of martins and they will fit in it. The martin will stick his head in and make it appear as if he can not fit. He may even appear to squeeze and push, to no avail. Trust me though, if the entrance is either bought from a reputable source such as www.EntrancesbySandy.com or www.PurpleMartins-R-Us.com or comes pre manufactured, the sizes are carefully measured and the bird can fit. Be patient. Many landlords suggest keeping a few round holed compartments available.  The rounds will fill first but the desire to stay together at the colony will get the other martins to eventually get in the starling resistant entrances. Of course you must intensify the battle against any starlings, as they will now be focused on the few round nests that remain. This will buy some time for the martins to become familiar with the change and master the entrances.  It just will take time. A couple of days at the most.

Consider building  a repeating nestbox trap or purchase one pre built. Also called a S&S trap these can trap repeatedly without resetting. Since the trapped bird is released into a holding cage, the trapped birds can tolerate it much better than a conventional nest trap. That is to say, if you leave the house for a few hours and a native bird is trapped in the repeater, they will be none the worse for wear when you get home. In a regular nest trap, the bird won’t do well at all. I would never recommend leaving a regular nest trap set while not actually watching it. Stuck in a closed off gourd or house with little air flow-It gets hot quick. Also you can stick the repeating nest box trap in a spot that is less desirable to the martins and lure the starlings away from your martin housing.

If your colony is new, that is you are still trying to attract your first pairs of purple martins, then converting them can be a bit trickier. Hopefully the martins that come to investigate your site come from a colony that uses SREH. If they are familiar with them they will enter the compartments like quicksilver. If they are not familiar with SREH then leaving from a couple of entrances  to half the compartments with round entrances will work. Monitoring your housing and keeping starlings out becomes even more important to these new colony sites and trapping and neutralizing is key. Local Starling population control can reduce the pressure form these invasive birds and increase the possibility of attracting and keeping your first pairs of martins.

Now for the downside. Though SREH are a wonderful tool that has helped martins to flourish in otherwise starling infested areas, their are risks. Though not common, Wing Entrapment can kill if not caught. I have encountered this problem a couple of times at our colony and you can read about Wing Entrapment HERE. When using SREH it is recommended that you look at your colony twice a day to observe for any martins that may be entrapped. Entrapment usually happens at the peak of martin breeding season when martins will often have territorial fights within the nest. The birds back up to the entrance while fighting and get their wings stuck. Lowering your housing and gently removing the stuck bird will not only save the life of the martin that is stuck but the 1 or 2 other martins that (I guarantee) are in the gourd with it.

Unfortunately there are no sparrow resistant entrances, when it comes to Purple Martin houses. So getting a good trap either nestbox or a baited trap becomes essential.

REMEMBER, when using traps of any type, monitoring is essential to preventing harm to native birds that may be inadvertently trapped. Native birds may not “learn” that it is a trap and are often caught repeatedly. If you are unable to monitor your traps they should be disabled while you are away.


Credits and copyrights are/may be in effect for SREH designs

Dually entrance design by Ken Landry

ACE entrance designed by R. C. Moser and developed by Bob Flam.

Excluder entrance designs by Duke Snyder

Conley entrance designs* by Willie Conley

© PurpleMartins-R-Us.com