Cliff swallows are perhaps the most architecturally creative hirundinids in North America and build nests that provide a secure environment for their young. These mud ?jugs? have a tunnel/funnel like entrance, which usually points downward and opens into the nesting chamber. If you were to give an IQ test to North American swallows, the cliff would probably score the highest!
You can create cliff swallow like nesting cavities from natural gourds without adding any kind of artificial extender. What you do is select natural gourds with long thick necks, which can be straight or curved, and a round or elongated bowl where the nesting chamber is located. Cut the neck to create about a two to two and half inch round hole to serve as the entrance. Gourd necks tend to be funnel shape whereby the inside gradually widens until reaching the bowl. Then it may drop down vertically for a few inches. These natural funnels may either protrude straight out or curve downward or even sideways and can vary in length from three or more inches in length. Martins can easily enter the entrances and ?waddle? down the rustic interiors without slipping or sliding. There is no need to add any kind of artificial extender or perches to such entrances as Mother Nature has naturally provided the perfect portal for the martins. Martins can easily cling to the gourd substrate and enter the nest hole.
In 2005, I used 26 funnel gourds and these have straight, angled and downward pointing funnel entrances and 22 were occupied by martins. These funnels vary between three to around six inches in length and the gourd bowls are between nine and 11 inches in diameter. This is producing excellent horizontal depth from around 12 to over 15 inches and good vertical descent to the nesting chamber.
Funnel gourds create a nesting chamber that is significantly protected from the watching eyes of owls and rain soakings. The downward sloping funnels provide the best security for the martins. The martins are hidden deep inside the horizontal gourd design with a narrow funnel entrance area that tends to restrict visibility inside the nesting chamber and reduces the chances that any avian predator could easily reach the contents. Martins may be attracted to entrance areas that are narrow like those found in natural woodpecker cavities. Such entrances restrict visibility inside and greatly reduce the chances that owls can reach the nest contents.
However, on a number of my funnel gourds, the neck area was too short after cutting the end. I had a round hole and the funnel was hardly noticeable and extended out only an inch or two. So on these types, I attached PVC joint pipe connectors (couplers), both straight and angled, to extend the neck area out and create a tunnel which transitions into a more funnel like opening prior to reaching the nesting chamber. Some of my PVC connectors pointed downward like a natural gourd neck. I attached the connectors with adhesive and aluminum strips used like ?band aids?. These PVC connectors are used to join two inch diameter pipes and the hole produced is around two and half inches. The connectors are about three or four inches in length and when added to the gourd neck area, the final tunnel/funnel averaged between five and six inches. The angled connectors create about a 45 degree turn.
Since PVC is plastic and slick, martins may have a hard time entering and clinging to such a substrate. So I roughed up the inside of each connector and then smeared adhesive all over the area where martins would climb on to create a rippled surface. The adhesive was the same I used to attach the connectors to the gourds. To make sure martins could easily enter these PVC extenders, I also attached ?oval? shaped wire perches to the bottom of each of the PVC extenders using No. 10 plastic coated copper wire. I drilled two small holes about an inch inside at the bottom of the PVC connector and inserted the wires through them and bent the wire ends. This created a perch which protrudes about three or four inches out from the bottom of the PVC extender. I also smeared adhesive around the area where the wires contacted the PVC to fill in any possibly crevice that could catch a toenail. Martins can easily sit on these wire perches and enter the holes.
Below are some photos showing martins using these funnel gourds, including ones with PVC pipe connectors/perches added. These gourds were very popular with the martins this year and many youngsters were raised in them. I hope to add more funnel gourds to my colony in the future.
Steve
