The Prothonotary Warbler Recovery Team s Nest Box Program in Canada

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1 The Prothonotary Warbler Recovery Team s Nest Box Program in Canada Location, Location! Produced by Bird Studies Canada 2009 If you re thinking of putting up nest boxes to benefit Prothonotary Warblers in Canada, you need to have suitable habitat (see below) that occurs in southwestern Ontario. There is little point in erecting nest boxes in regions where Prothonotaries seldom, if ever, occur. The species is simply so rare and localized that the chances of a bird discovering a nest box in a location that is far removed from where Prothonotaries might be expected to occur is very small. As such, there is little use in putting nest boxes in locations that are farther than about 20 km from the Lake Erie or Lake St. Clair shorelines or from the extreme southern end of Lake Ontario. Nest Box Materials and Dimensions We've done a bit of experimenting with PVC designs with little success, and really do prefer wood. We've avoided the Metamucil jar designs that have been used with some success in one location in Ohio, since they seem to exhibit relatively poor fledging success (perhaps they get too hot?). We also avoid the wax-board milk carton designs that have been used elsewhere, but Figure 1: Adult Prothonotary male tending a nest box (photo: Jon McCracken) have since fallen out of favour since they have a very short standing life and are difficult to fasten to poles and protect against mammalian predators. The boxes we use are constructed of wood. Rough ¼ (or even ½ ) untreated lumber is fine. Pressure-treated lumber should be avoided, owing to potential toxic effects. Plywood does not weather well. The most critical dimensions are as follows (see Figure 2): 1) diameter of entrance hole = 1 3/8 (1 ½ is OK, but no smaller) 2) interior floor dimension = 4 x 4 3) distance from floor to top of entrance hole = 5 inches.

2 As you'll see, the overall size of the box is fairly small. The roof should be constructed to allow a bit of an overhang on the sides and front (about an inch is more than adequate), and should be angled downwards a bit to repel the elements. We find that tacking an asphalt shingle on the roof top greatly helps increase the longevity of the box, but this isn't essential. We ve used various designs in terms of opening mechanisms for box checking, but recommend a hinged roof design, using an eye screw to secure the roof lid to the top edge of the box front. We stain the exterior of the box grey (water-based transparent stain) to help preserve it and make it more natural looking. Figure 2. Critical dimensions of Prothonotary Warbler nest boxes used in Canada. 2

3 Nest Box Mounting It is essential that the boxes are mounted on slippery, metal poles. 1" stainless steel or galvanized conduit is best, since it is slippery and won't rust. You can purchase these poles in 8 foot lengths. You need to spray paint the poles with black, green or grey flat paint so that it loses its shine and doesn t attract predators (or curious humans). Mounting on metal poles (rather than trees) will afford the boxes much, much greater protection against raccoons and squirrels. In fact, there is little point in fastening boxes to trees. As an extra measure, we also install predator guards (cones) on the poles. Even so, avian predators (e.g. jays) and even flying squirrels can still access the box contents. No system is 100% predator proof, but the goal is to minimize the risk. Depending on site conditions, you may be able to manually push the pole deep enough into light muck. Otherwise, we use a post pounder to drive the pole in to a depth of about 6-8. You don t usually need to drive the pole deeper than that, and may even want to avoid it, since it will be very difficult (if not impossible) to remove it if you later change your mind and want to relocate it. You can easily make your own post pounder using a threaded 4-foot length of 4 galvanized plumbing pipe with a metal cap threaded tightly on to the top. The post-pounder pipe is then just slid over top of the nest box pole and you simply tap the pole into place (vertically). Placement in Suitable Habitat The boxes need to be erected directly over expanses of open water in swamp forest habitat, which is usually strongly dominated by species like silver maple in Canada. The sites need to be expected to retain standing water through at least the end June, at least in most years. At the start of the season in early May, water depth should be at least 2 feet (more is better; 3-4 feet is ideal). There should be at least a 1-acre expanse of continuous open water (about 30 m x 30 m). Boxes can also be erected along the borders of slow-moving, warm water creeks, provided that there is ample canopy cover (a forested corridor that is at least 30 m on either side of the creek should be adequate). When placing boxes along creeks, however, be aware that they'll likely be exposed to spring flooding events and ice scour. Many of our floodplain boxes have been flooded out or taken out entirely by floods and ice. Boxes should be placed in partially shaded areas that receive some sunlight at least part of the day (e.g. about 70%-90% canopy cover is ideal). Make sure there is an ample supply of moss growing at the site the more the merrier. Prothonotaries generally do not occupy areas that have little or no moss in the immediate vicinity of the nest site. Moss is their essential nesting material. Nest Box Orientation and Configuration Place the boxes so that the nest hole is at eye-level height (about 5 feet). We attach the boxes to the poles by screwing (not nailing) a length of 1 1/2" wood strapping to the back of the box, and then use a couple of large hose clamps to secure the top 3

4 and bottom of the strapping to the pole. With hose clamps, the height and orientation of the boxes can be easily adjusted if need be. They can also be easily removed for maintenance. We try to orient the boxes such that there is a shrub, downed tree, or low overhanging branches about 10 feet away from the box entrance (not closer since this will facilitate predation from squirrels). This allows the fledglings something to land on (rather than the open water), and also gives the adults some low protective cover when entering and leaving the boxes. We avoid having low overhanging branches directly over the box, since this again invites access by squirrels. We group boxes in clusters of 2 (sometimes 3) boxes within about 20 feet of one another in suitable habitat, with clusters spaced at about 50 m intervals if the area of suitable habitat warrants more than one cluster. This cluster design increases territory "quality" for males who like to build one or more "dummy" nests. However, if you've got potential wren problems, then the cluster design just seems to exacerbate the problem. Nest Box Competitors Speaking of wrens, we now ONLY install boxes in habitat where House Wrens are either absent or occur only in very low numbers. Hence, we ALWAYS do a quick survey of the potential site during the breeding season to see whether wrens are already present. You can usually just look at a habitat and get a pretty good idea of what level of competition to expect from wrens. If at all possible, you want to select swamp forests that are large (30+ acres) and have relatively unbroken canopies. Wrens love edge type habitats. Wrens are extremely serious competitors for nest sites in some areas, so extreme caution is needed. If one or more wrens are already present within 200 m of the proposed nest box site, there is NO point in installing nest boxes, since they will assuredly all be taken over by wrens. In fact, you risk destroying otherwise suitable Prothonotary Warbler nesting habitat if you erect boxes in sites that are likely to be exposed to wren competition and wren vandalism. Tree Swallows can also be quite problematic, especially in open, exposed areas with little shade. It is best to locate boxes in shaded areas. Even so, the swallow problem can often be dealt with if two boxes are attached, back to back, to the same pole ( twinned ). Swallows that occupy one box won t tolerate another swallow pair in such close proximity. However, swallows will tolerate a family of Prothonotaries in the other box. Box twinning, however, is a useless strategy at sites occupied by wrens. In heavily forested sites, Black-capped Chickadees will also occupy many boxes. Twinning boxes may also be a good idea at these sites. 4

5 Nest Box Monitoring Naturally, a coordinated system of box monitoring is essential in order to evaluate the program s success at each site and make adjustments to it if necessary, especially if wrens start to pose a problem. As such, each box location must be georeferenced using a GPS (using NAD 83) and assigned a unique identifier so it can be tracked over time. Use a big black permanent magic marker (or house paint) to mark the box # on the box. If a box is later moved to a new location, then it must get another new unique number (e.g. add a year suffix to the original #, so that box #3 that was originally erected in 2009 becomes box #3-10 in 2010 if it is relocated). All relocated boxes must be GPSed. We try to check each box at least weekly through the entire course of the breeding season, starting in mid May right through the first week of July. Boxes are checked more frequently (at 3-5 d intervals) if there is any indication of Prothonotary activity. At the end of the season (i.e. about 5-7 July), we strongly encourage you to seal the box entrance with a stubby dead stick. This will prevent mice and squirrels from occupying the box over the winter and the following spring, prevent jays from using it as an acorn larder, and prevent late-nesting wrens from moving in. At the start of the following spring (late April), you naturally need to go back in and remove the plugs. If in Canada, we highly recommend that you register your nest box program with the recovery team experts, who will be only too happy to monitor your boxes and provide you with regular status reports. If you prefer to monitor your own boxes, you will be supplied with standard data sheets and protocols to be adhered to. You must submit all required data to the recovery team no later than 1 August each year in the format provided. Figure 3: Checking a nest box (photo: Phil Roberts) 5

6 Are there Legal Implications of Erecting Nest Boxes on Private Lands? All migratory birds, their nests and eggs are legally protected under Canada s Migratory Bird Convention Act. Moreover, endangered species like the Prothonotary Warbler receive additional special protection from the federal Species at Risk Act (SARA) and Ontario s Endangered Species Act (ESA). What this basically means is that you should not embark upon a nest box program unless you have a serious interest in the protection and recovery of the species. Agreeing to place Prothonotary Warbler nest boxes on your property means that you have legal obligations not to harm the birds, their nests, and their habitat for as long as the nest boxes (or birds) remain on your property. For the most part, this means that you ll be able to enjoy your property s natural heritage values as you currently know them. This means that all current land-use activities will continue to be permitted, including hunting, fishing, birding, hiking, and even judicious logging (we re happy to provide on-site advice about the latter). However, any activities that directly affect the long-term protection of Prothonotary Warbler habitat (e.g. changes in municipal zoning bylaws) may well be restricted. This includes restrictions on incompatible industrial, commercial or urban/residential development, or major changes in hydrology of the affected wetland. The recovery team is only too happy to provide advice to landowners who want to aid in the maintenance or recovery of swamp forest habitat in southern Ontario. For information on the Prothonotary Warbler recovery program in Canada, contact: Jeff Robinson Environment Canada Prothonotary Warbler Recovery Team Chair Jeff.Robinson@ec.gc.ca work phone: Sandy Dobbyn Ontario Ministry of Natural Resources Sandy.Dobbyn@ontario.ca work phone: Jon McCracken Bird Studies Canada jmccracken@bsc-eoc.org work phone: (ext. 115) 6

7 The mossy beginnings of a Prothonotary Warbler nest. Photo: Phil Roberts A Prothonotary Warbler nestling. Photo: Phil Roberts 7

8 A Prothonotary Warbler nestling getting ready to fledge. Photo: Yousif Attia Within a few minutes of fledging, the young Prothonotary Warbler is already working its way up into the tree canopy. Can you spot him? Photo: Yousif Attia 8